Interpreting Microscopic Positive Margins in Differentiated Thyroid Cancer

  • Clin Thyroidol 2021;33:184–186.
  • Background
    • Disease-specific survival for differentiated thyroid cancer (DTC) is lengthy and most profoundly impacted by:
      • Patient age (55 years)
      • Distant metastases
      • Extent of gross extrathyroidal extension (ETE)
      • Nodal status
    • Microscopic margin positivity (R1 margin):
      • Has shown no impact on local recurrence, but it has not been studied as:
        • A marker of completeness of resection
    • This National Cancer Database (NCDB) study evaluated the impact of R1 margin on overall survival in DTC to determine the presence of modifiable factors such as institutional annual thyroidectomy volume and hospital setting of thyroidectomy
  • Methods
    • The NCDB was queried for adults (ages 18 to 90) who underwent surgery from 2004 to 2016 for treatment of well- and moderately-differentiated thyroid carcinoma with a primary tumor size of 1 to 4 cm
    • Patients with histologically aggressive variants were excluded
    • Patients with gross ETE into the strap muscles (T3b); subcutaneous soft tissues, larynx, trachea, esophagus, or recurrent laryngeal nerve (T4a); or invading prevertebral fascia, encasing carotid or mediastinal vessels (T4b), or nodal disease were included if primary tumor size was less than 4 cm
    • Binary logistic-regression analyses evaluated factors affecting margin positivity after adjusting for confounders including age, gender, comorbidity score (modified Charlson–Deyo), extent of thyroid operation (lobectomy or total), margin status, lymphovascular invasion, multifocality, institutional annual case volume for thyroidectomy, and institu- tion type (community, comprehensive community, academic, or integrated network
  • Results
    • This study included 14,471 patients with DTC (median age, 47.52 years [range, 18–90]; 74.7% female)
    • After correcting for confounders, disease-specific (nonmodifiable) factors impacting survival included:
      • ETE:
        • 25.2% of patients; OR, 1.47; P = 0.001), lateral neck nodal disease (12.6%; OR, 1.73; P = 0.001
      • Lymphovascular invasion:
        • 15.7%; OR, 1.32; P = 0.044
      • R1 margin:
        • 15.3%; OR, 1.46; P = 0.038
    • Modifiable factors impacting survival included:
      • Institutional case volume and type of facility:
        • Overall, institutions had a mean case volume of 30.3 thyroidectomies per year (range, 4 to 485):
          • When evaluating R1 margin status as a modifiable risk factor for survival:
            • Treatment in academic / research facilities (OR, 0.623; 95% CI, 0.527–0.738; P<0.001), integrated networks (OR, 0.782; 95% CI, 0.654–0.934; P = 0.009), or facilities with higher case volumes (OR, 0.979; 95% CI, 0.978–0.982; P = 0.004):
              • Was associated with lower odds of R1 margin
    • This study was sufficiently powered to detect a small impact of R1 margin on 8-year survival:
      • OR, 1.464; 95% CI, 1.039–2.121; P = 0.038
  • Conclusions
    • In this large database study:
      • R1 margin in DTC impacted overall survival
      • Modifiable risk factors associated with decreased risk of R1 margin were:
        • Treatment in an academic / research facility or integrated network and higher institutional annual case volume
  • As the thyroid gland has an incomplete capsule:
    • Interpreting an R1 margin as a prognostic indicator in DTC has been the source of some confusion
  • A meta-analysis of patients with DTC:
    • Found no association between R1 margin and local recurrence
  • This study aimed to evaluate the impact of negative versus R1 margins in a more homogeneous population of patients with smaller DTCs
  • The major modifiable factor in this study was care setting:
    • Higher-volume thyroid surgeons are more likely to operate in academic settings
    • Worldwide, higher individual surgeon volume for thyroidectomy (30 to 100 cases / year) is protective against complications and yields better oncologic outcomes
    • A similar NCDB study with a more heteroge- neous thyroid cancer population confirmed that treatment in an academic center was associated with a lower probability of R1 margin and higher overall survival
  • Rather than contradicting prior studies about the seeming irrelevance of R1 margin in DTC:
    • This study highlights how R1 margin may be a marker of incomplete resection when thyroidectomy is performed in low-volume centers
    • When I receive pathologic “positive margins,” assuming no ETE was present intraoperatively:
      • I generally reassure the patient that all tumor was appropriately resected:
        • However, this study raises important questions about how to interpret pathology reports documenting R1 margin from lower-volume centers
  • In contrast to this study’s findings of improvement in mean overall survival with negative margins:
    • Prior retrospective studies have not found that R1 margin impacts overall survival
  • Although this study corrected for confounders:
    • ETE was the variable most strongly correlated with an R1 margin (OR, 2.8):
      • ETE decreases survival in thyroid cancer, and it makes sense that ETE would be a natural continuation of R1 margins
        • However, further research is needed to determine the prognostic significance of thyroid cancers with positive inked margins without a finding of gross ETE

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Withholding Radioactive Iodine for Lower-Risk Papillary Thyroid Cancers Is Safe, but Delays the Certainty of Treatment Response

  • Clin Thyroidol 2021;33:117–120.
  • Background
    • The past 10 to 15 years have seen two related paradigm shifts in the care of patients with papillary thyroid cancer:
      • Risk-stratification systems:
        • Have been developed and validated, which have allowed clinicians to recognize patients with an excellent prognosis
      • Treatment guidelines:
        • Have also undergone rapid change, particularly for patients with lower-risk cancers
      • These changes, which have led to a trend of less aggressive treatment of low-risk patients:
        • Have been controversial
    • One area of extreme controversy has been when to use postoperative radioactive iodine ablation
    • There are important reasons why the conser‐ vative use of radioactive iodine is ideal:
      • In the face of an excellent prognosis, salivary and lacrimal treatment-related adverse events, or even the potential of an increase in the rate of second cancers, become important:
    • However, proponents for the increased use of radioactive iodine point to:
      • Its usefulness in completing risk stratification
    • This study was a retrospective analysis of patient outcomes from a single Italian center (Sapienza University of Rome) before and after a policy change for the use of postoperative radioactive iodine
    • Prior to 2011 at this institution, most patients with papillary thyroid cancer had received radioactive iodine following total thyroidectomy as a standard procedure
    • In 2011, the default position changed for patients in whom the estimated risk of recur‐ rence was ≤ 8% and decision-making was deferred for approximately 12 months:
      • In this later group, delayed radioactive iodine ablation was recommended if:
        • The serum thyroglobulin concentration was ≥ 1 ng/mL
        • There is imaging evidence of persistent disease or
        • At the patients request
  • Methods
    • Patients initially treated between 2005 and June 2011 were managed in the more aggressive radioactive iodine era (cohort 1; 116 patients)
    • Cohort 2 included 156 patients initially treated from July 2011 to December 2018
    • Follow-up was performed 3 months after surgery and then at least yearly, with analysis performed at 12 months, 3 years after surgery, and at last contact
    • Outcomes were classified according to dynamic risk-stratification criteria validated for patients undergoing total thyroidectomy followed by radioactive iodine, as stratified by:
      • Excellent response:
        • No clinical, biochemical, or structural evidence of disease with a very sensitive cutpoint for serum thyroglobulin of ≤ 0.2 ng/ml)
      • Indeterminate response:
        • Detectable but low serum thyroglobulin levels, positive thyroglobulin antibodies, or abnormal but nonspecific imaging findings
      • Biochemical incomplete response:
        • Abnormal serum thyroglobulin levels or rising thyroglobulin antibodies
      • Structural incomplete response:
        • Identifiable locoregional or distant metastatic disease
    • Analyses were performed by comparing numbers of patients with structural incomplete response with those with other outcomes, and “gray-zone” responses (indeterminate or biochemical incomplete response) with “black-or-white” responses (excellent or structural incomplete responses)
    • Modeling approaches attempted to account for potential confounding
  • Results
    • In cohort 1, of the 116 patients, 90 (plus one additional patient during a median follow-up of 8 years) received postoperative radioactive iodine ablation
    • In cohort 2, of the 156 patients, 10 (plus three additional patients during a median follow-up of 4 years) received postoperative radioactive iodine
    • Apart from follow-up time, the only key tumor feature that differed between cohorts was a smaller median tumor size in the group from the later period (10 mm vs. 7 mm; range, 1–45 and 1–60 respectively)
    • Structurally incomplete responses were very rare in both cohorts and at all time points analyzed (1% to 3%, P=not significant)
    • Significantly higher proportion of gray-zone responses was apparent at 1 year of follow-up in cohort 2, driven mostly by the presence of more indeterminate responses due to serum thyroglobulin antibody positivity in that group (8.6% in cohort 1 vs. 18.6% in cohort 2)
    • While these statistically significant differences did not persist at final follow-up, gray-zone responses were very common and remained numerically higher in cohort 2 (30% in cohort 1 and 44% in cohort 2, from a combination of detectable serum thyroglobulin levels, persistent positive serum thyroglobulin antibodies, and non‐specific imaging findings
  • Conclusions
    • In this longitudinal cohort study, structural incomplete responses were rare in lower-risk papillary thyroid cancer patients, whether or not they received radioactive iodine ablation:
      • However, less use of postoperative radioactive iodine does lead to a higher rate of “uncertain” disease response status, at least initially
  • This study supports the success of modern risk-stratification systems in identifying patients with very low risk of structurally persistent or recurrent differentiated thyroid cancer:
    • Whether or not postoperative radioactive iodine ablation is given
  • It builds on previous work showing low rates of recurrence in appropriately selected patients treated with surgery alone and should not surprise those familiar with the literature
  • Clinicians can be reassured that withholding radioactive iodine in lower-risk patients rarely results in the development of clinically significant recurrent disease:
    • Acknowledging that most patients treated in this study had small, localized tumors and that follow-up was relatively short
  • The other key message of the study is the trade-offs that occur between a more aggressive and a more conservative approach to radioactive iodine pre‐ scription:
    • At least in the short term, not administering postoperative radioactive iodine led to a lower chance of “certainty” in the success of the treatment response:
      • This gray-zone outcome was due to a combination of:
        • Detectable serum thyroglobulin (at extremely low levels), persistently positive serum thyroglobulin antibodies, and
        • Nonspecific imaging findings being more common in patients not receiving radioactive iodine
  • Without a considered response, higher rates of gray-zone outcomes could lead to increased patient (and physician) anxiety and / or an increase in diagnostic procedures associated with hunting for low-volume structural recurrence
  • Limiting these possibilities (and the side effects of overtreatment with radioactive iodine) requires attention to the biology of each patient’s thyroid cancer, a care team working together with consistent communication, careful discus‐ sion with patients about how common gray-zone responses are and relating that the majority do not represent recurrent disease, and assessment of the trends in each patient’s biochemical and imaging response over time
  • Consultations take longer, and depending on a clinic’s imaging protocols, may result in an increase in ultrasound use to follow up on nonspecific imaging findings
  • Flexibility is also required, particularly in recognizing that some patients’ anxiety can be reduced only by radioactive ablation and that the rare requirement for delayed radioactive iodine administration is not necessarily a treatment failure
  • This study, therefore, adds a valuable contribution to the literature, in highlighting the issues of certainty trade-offs that occur with current trends toward less aggressive treatment of lower-risk differentiated thyroid cancers

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What Is the Ideal Age Cutoff for Papillary and Follicular Thyroid Cancer Staging, and Should the Cutoffs Be Different?

  • Clin Thyroidol 2021;33:177–179.
  • Background:
    • The Union for International Cancer Control (UICC) and the American Joint Committee on Cancer (AJCC) tumor, node, metastasis (TNM) staging system:
      • Is designed to predict disease-specific survival
      • Differentiated thyroid cancer (DTC) is the only malignancy that includes an age cutoff in determining stage within this system
    • The previous AJCC 7th edition used an age cutoff of 45 years:
      • In which patients under the age of 45 could not be staged higher than stage II
    • While the updated 8th edition now uses 55 years:
      • As this threshold for both papillary thyroid cancer (PTC) and follicular thyroid cancer (FTC)
    • Multiple studies have shown age 55 years to be superior to 45 years as a cutoff for DTC, but questions remain on other potential age cutoffs for DTC
    • PTC and FTC are staged together as DTC, given their similar disease-specific survival:
      • Yet it has not been established whether PTC and FTC should have the same age cutoff, given that they can have different clinical courses:
        • PTC is more likely to have regional lymph node metastasis and FTC to have distant metastasis
    • The present study aims to investigate the optimal cutoff for the TNM staging the system for DTC, using the histopathologic criteria of the 8th edition, and also to examine optimal age cutoffs for both PTC and FTC
  • Methods
    • The current study is a retrospective analysis of two well-established databases from The Netherlands and Germany
    • Patients were age 18 years and above who were treated for either PTC or FTC between 2002 and 2016 (Erasmus Medical Center database) or between 1980 and 2015 (University of Würzburg database)
    • All patients underwent thyroid surgery and were treated according to standards at the time
    • Demographic, disease, treatment, and mortality data were obtained
    • Patients were reclassified using the histopathologic criteria from the TNM 8th edition with different age cutoffs
    • Age cutoffs were analyzed at 5-year increments from 20 up to 85 years and by 1-year increments between 35 and 55 years
    • Analysis was done for the combined DTC patient population and separately for PTC and FTC
    • Disease-specific survival was analyzed using the Kaplan–Meier method and compared across stages using the log-rank test
    • The concordance index (Harrell’s C-index), Akaike information criterion (AIC), and Bayesian information criterion (BIC) were used to assess the statistical model performance at different age cutoffs
    • The model with the highest C-index and lowest AIC and BIC was considered to be the best
  • Results
    • A total of 3074 patients were included (820 from Erasmus Medical Center and 2254 from University of Würzburg)
    • Of these patients, 2355 (77%) had PTC and 719 (23%) had FTC, with a median follow-up of 84 months
    • The mean age was 48.7 years, and 69.5% were female
    • Overall, 23.1% had lymph node metastasis and 8.8% had distant metastasis
    • When compared to patients with PTC, patients with FTC:
      • Were older (54.2 years vs. 47.1 years; P<0.001), more likely to be male (37.1% vs. 28.5%; P<0.001), less likely to have lymph node metastasis (9.2% vs. 27.3%; P<0.001), and more likely to have distant metastasis (18.2% vs. 6.0%; P<0.001)
    • Using the 8th edition’s age cutoff of 55 years, 2430 patients (79%) were classified as stage I, 384 (13%) as stage II, 88 (3%) as stage III, and 172 (6%) as stage IV
    • Lowering the age cutoff :
      • Lowered the number of patients in stage I
    • Increasing the age cutoff:
      • Increased the number of patients in stage
    • The 10-year disease-specific survival for DTC was 94.7% and was significantly higher for patients with PTC than for those with FTC (96.5% vs. 89.5%; P<0.001)
    • For DTC, PTC, and FTC, the majority of age cutoffs performed better in the statistical model than did no age cutoff
    • Using 5-year increments for the age cutoffs:
      • DTC and PTC had the best performance, with an age cutoff of 50 years
      • While FTC was 40 years
    • Using 1-year increments:
      • DTC performed best, at an age cutoff of 50 years, PTC at 48 years, and FTC at 41 years
  • Conclusions
    • When using the histopathologic criteria of the 8th edition TNM system:
      • The optimal age cutoff for DTC to predict disease-specific survival is 50 years, rather than 55 years as is currently in use
      • The optimal age cutoff for PTC is also 50 years
      • While the age cutoff for FTC should be 40 years:
        • Signifying that the age cutoffs for PTC and FTC should be different

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Can rhTSH (Thyrogen) be used as an alternative to thyroxine withdrawal for remnant ablation or adjuvant therapy in patients who have undergone near-total or total thyroidectomy?

  • In patients with American Thyroid Association (ATA) low-risk and ATA intermediate- risk DTC without extensive lymph node involvement (i.e., pT1 to pT3, cN0 / cNx/ pN1a, M0) in whom radioactive iodine (RAI) remnant ablation or adjuvant therapy is planned:
    • Preparation with rhTSH stimulation:
      • Is an acceptable alternative to thyroid hormone withdrawal for achieving remnant ablation:
        • Based on evidence of superior short-term quality of life, noninferiority of remnant ablation efficacy, and multiple consistent observations suggesting no significant difference in long-term outcomes
  • In patients with ATA intermediate-risk DTC who have extensive lymph node disease (multiple clinically involved LN) in the absence of distant metastases:
    • Preparation with rhTSH stimulation may be considered as an alternative to thyroid hormone withdrawal prior to adjuvant RAI treatment
  • In patients with ATA high-risk DTC with attendant higher risks of disease-related mortality and morbidity:
    • More controlled data from long-term outcome studies are needed before rhTSH preparation for RAI adjuvant treatment can be recommended
  • In patients with DTC of any risk level with significant comorbidity that may preclude thyroid hormone withdrawal prior to iodine RAI administration:
    • rhTSH preparation should be considered
      • Significant comorbidity may include:
        • A significant medical or psychiatric condition that could be acutely exacerbated with hypothyroidism, leading to a serious adverse event
        • Inability to mount an adequate endogenous TSH response with thyroid hormone withdrawal

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How long does thyroid hormone need to be withdrawn in preparation for RAI remnant ablation / treatment or diagnostic scanning?

  • American Thyroid Association Recommendation # 53:
    • If thyroid hormone withdrawal is planned prior to radioactive iodine (RAI) therapy or diagnostic testing:
      • Levothyroxine (LT4) should be withdrawn for 3 to 4 weeks
      • Liothyronine (LT3) may be substituted for LT4 in the initial weeks if LT4 is withdrawn for 4 or more weeks:
        • In such circumstances, LT3 should be withdrawn for at least 2 weeks
    • Serum thyroid stimulating hormone (TSH) should be measured prior to radioisotope administration to evaluate the degree of TSH elevation:
      • A goal TSH of greater than 30 mIU/L has been generally adopted in preparation for RAI therapy or diagnostic testing:
        • But there is uncertainty relating to the optimum TSH level associated with improvement in long-term outcomes
      • Thyrotropin stimulation before RAI remnant ablation / therapy or scanning has been a long-established standard of care because early observational research suggested that:
        • A TSH greater than 30 mIU/L was required for incompletely resected thyroid tumors to significantly concentrate 131I
      • There have been two RCTs comparing various thyroid hormone withdrawal protocols prior to therapeutic or diagnostic iodine radioisotope administration:
        • Lee et al. reported on an open-label, single-center study, in which 291 patients with well-differentiated thyroid cancer (TNM stage T1 to T3, N0 / N1a, M0) were randomized to either with- drawal LT4 for 4 weeks (n = 89), or withdrawal of LT4 for 4 weeks with substitution of LT3 for the first 2 weeks (n = 133), or recombinant human TSH (rhTSH; with withdrawal of LT4 for a few days from the time of the first rhTSH injection to radioisotope administration) (n = 69):
          • In this trial, all patients received 30 mCi of 131I for remnant ablation and were prescribed a 2-week low-iodine diet (LID) pre-ablation
          • Although the randomization method was unclear, the baseline characteristics (including pre-ablation urinary iodine measurements) were well balanced among groups
          • Furthermore, the pre-ablation TSH was greater than 30 in all patients in all groups in this trial, with no significant difference in mean pre- ablation TSH levels
          • Moreover, the primary outcome, which was the rate of successful remnant ablation at 12 months:
            • Was not significantly different among groups:
              • Range 91.0% to 91.7% among groups
          • Upon administration of questionnaires in a double-blind fashion, there was no significant difference in quality of life during preparation for RAI ablation, between the LT4 withdrawal group and the LT4 withdrawal with LT3 substitution group:
            • However, quality of life in both withdrawal groups prior to remnant ablation was significantly worse than after rhTSH preparation
          • Long-term outcome data from this trial were not reported
        • In a single-center trial, Leboeuf et al. randomized 20 individuals with well-differentiated thyroid cancer awaiting RAI remnant ablation or diagnostic scanning to:
          • LT4 withdrawal and either substitution of LT3 for 21 days, followed by 2 weeks off LT3, or identical-appearing placebo for LT3 for 21 days
          • In both groups, either the LT3 or placebo was withdrawn for another 2 weeks, and weekly measurements were performed for serum TSH, free thyroxine, and free triiodothy- ronine
        • The primary outcome was the hypothyroidism symptom score (Billewicz scale), which was ascertained in a double-blind fashion at time of LT4 withdrawal and every 2 weeks until the end of the study
        • The randomization method was a computer-generated number sequence; the LT3 group was significantly older than the placebo group (mean age 64 compared to 46), suggesting imbalance in the randomization
        • Disease stage of participants was not reported
        • Approximately 15% of participants withdrew from this trial
      • Leboeuf et al. reported no significant differences between the two thyroid hormone withdrawal protocol groups for hypothyroid symptom scores at any time point in the trial in a protocol-based analysis
      • At the time of ablation or whole-body scanning, the mean TSH was not significantly different between groups
    • In summary, available evidence from recent RCTs suggests that either direct LT4 withdrawal or LT4 withdrawal with substitution of LT3 in initial weeks is associated with similar short-term quality of life and hypothyroidism symptom scores; moreover, the remnant abla- tion success rate appears comparable
  • There is some conflicting observational evidence on whether any specific pre-RAI administration TSH level is associated with success of remnant ablation:
    • For example, in a secondary analysis of a RAI remnant ablation activity RCT, Fallahi et al:
      • Reported that a pre-RAI TSH of greater than 25 following (LT4 and LT3) thyroid hormone withdrawal was significantly associated with increased likelihood of successful remnant ablation (odds ratio 2.36, [95% CI 1.28–4.35], p=0.006), after adjustment for RAI activity, baseline serum Tg, on-LT4 TSH level, sex, age, histology, baseline RAI up-take, and extent of surgery
    • In two retrospective studies, each including several hundred DTC patients who underwent thyroid hormone withdrawal, no significant association was observed between pre-RAI TSH and rate of successful remnant ablation, in respective multivariable analyses adjusted for relevant variables such as disease extent, 131I activity, and gender:
      • However, results of these two studies may not necessarily be extrapolated to TSH levels below 30 mU/L, given that patients with such TSH thresholds were not generally considered eligible for RAI ablation in these studies
    • Pre–RAI ablation TSH was not a significant predictor of becoming disease free without further treatment in a secondary subgroup analysis of 50 patients who underwent thyroid hormone with- drawal, but the small number of patients in this subgroup may have limited the statistical power for a multivariate analysis
  • In summary, there is some uncertainty on the optimal level pre–RAI treatment TSH following thyroid hormone withdrawal in considering long-term outcome effect

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ATA Modified Risk of Structural Recurrence Classification – High Risk

  • A prospective multicenter study reported:
    • A significant improvement in:
      • Overall and disease-specific mortality, as well as disease-free survival:
        • In National Thyroid Cancer Cooperative Study Group (NTCTCSG):
          • Stage III and IV patients:
            • After statistical adjustment using multivariable and propensity stratified analyses
  • Furthermore, prospectively collected data from the SEER cancer registry:
    • Suggest that postsurgical RAI therapy is associated with improved overall survival:
      • In patients with PTC with distant metastases:
        • When distant metastases were combined with:
          • Age greater than 45 years
          • Tumor size greater than 2 cm
          • Positive lymph nodes at primary diagnosis
    • Data from the SEER database also suggest that overall survival:
      • In patients with FTC with distant metastases:
        • More than doubled in patients receiving postsurgical RAI treatment
  • Thus:
    • Routine postsurgical RAI treatment is re- commended in patients with ATA high-risk DTC

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Primary Goal of Postoperative Radioactive Iodine in Thyroid Cancer

  • Depending on the postoperative risk stratification of the individual patient:
    • The primary goal of postoperative administration of RAI after total thyroidectomy may include:
      • RAI remnant ablation:
        • To facilitate detection of recurrent disease and initial staging by tests such as Tg measurements or whole-body RAI scans)
      • RAI adjuvant therapy:
        • Intended to improve disease-free survival by theoretically destroying suspected, but unproven residual disease, es- pecially in patients at increased risk of disease recurrence)
      • RAI therapy:
        • Intended to improve disease-specific and disease-free survival by treating persistent disease in higher risk patients)
    • Additional considerations in RAI decision-making may include:
      • Patient comorbidities (and the potential impact of therapeutic doses of RAI or preparation for the procedure)
      • Feasible or preferred disease surveillance procedures
      • Patient preferences:
        • The latter being particularly important when clear data on therapeutic efficacy are lacking), or others

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Indications for Radioactive Iodine in the Management of Thyroid Cancer

  • RECOMMENDATION 51 of the American Thyroid Association
    • RAI remnant ablation is not routinely recommended after thyroidectomy for ATA low-risk DTC patients:
      • Consideration of specific features of the individual patient that could modulate recurrence risk, disease follow-up implications, and patient preferences are relevant to RAI decision-making
    • RAI remnant ablation is not routinely recommended after lobectomy or total thyroidectomy for patients with unifocal papillary microcarcinoma, in the absence of other adverse features.
    • RAI remnant ablation is not routinely recommended after thyroidectomy for patients with multifocal papillary microcarcinoma in absence of other adverse features:
      • Consideration of specific features of the individual patient that could modulate recurrence risk, disease follow-up implications, and patient preferences are relevant to RAI decision-making
    • RAI adjuvant therapy should be considered after total thyroidectomy in ATA intermediate-risk level DTC patients
    • RAI adjuvant therapy is routinely recommended after total thyroidectomy for ATA high risk DTC patients

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Who Needs Chemotherapy after Breast Cancer Surgery?

The benefit of chemotherapy among women with early-stage, hormone-receptor positive breast cancers has become largely determinant on the use of gene expression profiles, including Oncotype DX, MammaPrint, and PAM50. Oncotype DX score is a 21-gene assay that uses RT-PCR to calculate recurrence risk using a scoring system from 0 to 100, and categorizes women into low, intermediate, and high risk of recurrence based on pre-specified cut points. MammaPrint is a 70-gene assay performed with microarray, and classifies tumors as having good vs poor prognostic signatures. PAM50 tests 50 classifier genes and categorizes women by intrinsic subtypes including luminal A, luminal B, HER2-enriched, basal-like and normal-like. Adjuvant! Online is an online program that uses standard clinicopathologic variables to estimate survival for breast cancer patients treated by local therapy alone and the survival and disease-free survival benefit gained by the addition of systemic adjuvant therapy.

The 21-gene recurrence score assay (Oncotype DX)

  • The 21-gene recurrence score assay (Oncotype DX):
    • Is a reverse-transcriptase-polymerase-chain-reaction assay of:
      • 16 prospectively selected genes and 5 reference genes
    • Analysis is performed in:
      • Paraffin-embedded tumor tissue
    • This assay was developed from:
      • NSABP B-14 and validated with data and specimens from NSABP B-20
    • It estimates the 10-year risk of distant recurrence:
      • By categorizing results into:
        • Low-risk (RS< 18) group
        • Intermediate-risk (RS 18 to 30) group
        • High-risk (RS > 30) groups
    • A low recurrence score (RS < 18):
      • Predicts little benefit of chemotherapy
  • The 21-gene recurrence score assay:
    • Is proven to be prognostic for women with:
      • Node-negative
      • ER-positive breast cancer:
        • Treated with tamoxifen
  • Retrospective data obtained via optional tumor banking:
    • In accordance with the SWOG 8814 trial:
      • Which demonstrated postmenopausal women:
        • With node-positive, ER-positive tumors:
          • Achieved superior survival when:
            • Cyclophosphamide, doxorubicin, and fluorouracil:
              • Was given before tamoxifen
    • The SWOG 8814 trial:
      • Allowed for retrospective assessment of recurrence score on DFS by treatment group
      • Analysis demonstrated the recurrence score results:
        • To be both prognostic and predictive of benefit:
          • To adjuvant chemotherapy:
            • As there was no added benefit to adjuvant systemic chemotherapy:
              • In women with low recurrence scores and
              • There was an improvement of DFS:
                • In those with high recurrence scores
    • These hypothesis-generating results:
      • Serve as preliminary basis for the RxPonder trial:
        • Which is currently enrolling as a phase III trial
        • Randomizing women with hormone receptor-positive and HER2-negative breast cancer involving 1 to 3 lymph nodes and a 21-gene assay recurrence score of 25 or less to:
          • Endocrine therapy alone versus chemotherapy followed by endocrine therapy
    • The 21-gene recurrence score:
      • Is not used in patients with HER2-positive breast cancer
  • In women with hormone receptor positive (HR+), HER2-negative early breast cancer:
    • The 21-gene signature score provides prognostic information:
      • That is independent of clinical and pathological features
    • A high score (on a scale of 0 to 100):
      • Indicates a higher rate of distant recurrence
      • And is predictive of chemotherapy benefit
  • The prospective Trial Assigning Individualized Options for Treatment (TAILORx):
    • Showed that endocrine therapy alone was non-inferior to adjuvant chemotherapy plus endocrine (chemoendocrine) therapy:
      • In women with HR+, HER2-negative, axillary node-negative breast cancer and a 21-gene recurrence score of 11 to 25
      • An exploratory analysis indicated some benefit of chemotherapy in women 50 years of age or younger:
        • Who had a recurrence score of 16 to 25:
          • In this analysis there was a:
            • Small (~1.6%) chemotherapy benefit in distant disease-free survival for patients with recurrence score results from 16 to 20
            • Modest (~6.5%) chemotherapy benefit for patients with recurrence score results from 21 to 25
  • References:
    • Paik S, Shak S, Tang G, et al. A multigene assay to predict recurrence of tamoxifen-treated, node-negative breast cancer. N Engl J Med. 2004;351(27):2817-2826.
    • Paik S, Tang G, Shak S, et al. Gene expression and benefit of chemotherapy in women with node-negative, estrogen receptor-positive breast cancer. J Clin Oncol. 2006;24(23):3726-3734.
    • Albain KS, Barlow WE, Shak S, et al. Prognostic and predictive value of the 21-gene recurrence score assay in postmenopausal women with node-positive, oestrogen-receptor-positive breast cancer on chemotherapy: a retrospective analysis of a randomised trial. Lancet Oncol. 2010;11(1):55-65.
    • Ramsey SD, Barlow WE, Gonzalez-Angulo AM, et al. Integrating comparative effectiveness design elements and endpoints into a phase III, randomized clinical trial (SWOG S1007) evaluating oncotypeDX-guided management for women with breast cancer involving lymph nodes. Contemp Clin Trials. 2013;34(1):1-9.
    • Sparano JA, Gray RJ, Ravdin PM, Makower DF, Pritchard KI, Albain KS, et al. Clinical and genomic risk to guide the use of adjuvant therapy for breast cancer. New Engl J Med. 2019;380(25):2395-2405.
    • Sparano JA, Gray RJ, Makower DF, Pritchard KI, Albain KS, Hayes DF, et al. Adjuvant chemotherapy guided by a 21-gene expression assay in breast cancer. New Engl J Med. 2018;379(2):111-121.

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