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Who Needs a Repeat FNA Biopsy of a Thyroid Nodule?

Affirma Molecular Test

  • Tackling the question of benign versus malignant etiology from a another standpoint:
    • A gene expression classifier (GEC) was developed through an iterative process that intended for the test to have a high sensitivity and a high negative predictive value (NPV), analogous to the NPV of thyroid nodules diagnosed as benign on cytology
  • Intended specifically to aid in ruling out malignancy, the Afirma GEC was developed to possibly decrease the rate of diagnostic lobectomies in the case of indeterminate or suspicious thyroid nodules
  • A test with a high sensitivity and high negative predictive value (NPV) can rule-out cancer
  • A test sensitivity:
    • Measures the fraction of cancers that the test identifies as “positive” (Afirma GEC suspicious)
  • The Afirma GEC sensitivity among indeterminate nodules:
    • Is roughly 90%
    • A test NPV measures the fraction of “negative” calls by the test (Afirma GEC benign) that are correct
  • The Afirma GEC NPV is:
    • 94% to 95% amongst Bethesda III and IV nodules at a cancer prevalence of 24% to 25%
  • Although not mutually exclusive, a test with a high specificity and high PPV:
    • Is able to rule-in cancer
  • A test specificity measures the fraction of benign nodules that are called benign by the test
    • The Afirma GEC test specificity is 52%:
      • Signifying that just over half of the benign nodules are called GEC benign
  • A test PPV measures the fraction of “positive” calls by the test (Afirma GEC suspicious) that are correct
    • The Afirma GEC test PPV is 37% to 38% amid Bethesda III and IV nodules
  • Accordingly, the strength of the Afirma GEC is its ability to rule-out cancer (NPV), more than its ability to rule-in cancer (PPV)
  • A rule-in test is of significance when it changes clinical care:
    • Such as altering the extent of thyroid surgery from a lobectomy to a total thyroidectomy:
      • Hence, the effectiveness of a rule-in tests is currently questioned as patient benefit has not been established
  • Given the low specificity (52%) and PPV (37% to 38%) of Afirma:
    • It is not considered a rule-in test
  • Even though an Afirma GEC suspicious result raises the risk of cancer from 24% to 25% to 37% to 38%:
    • It should be clear that the asset of the test is that it finds just over one-half of all benign nodules with Bethesda III or IV cytology as genomically benign, and 90% of all cancers as genomically suspicious irrespective of the cancer prevalence
  • Therefore, when utilized as part of the diagnostic armamentarium for cytologically indeterminate nodules with a risk of malignancy of 25% or less:
    • The estimated accuracy of a benign result (NPV) is 94% or greater
  • Accordingly, the majority of the Afirma GEC benign nodules:
    • Are entrants for clinical observation instead of a diagnostic operation
  • Rare neoplasms that are often difficult to accurately diagnose with cytology such as:
    • Parathyroid neoplasms, medullary thyroid carcinomas (MTC), and metastases to the thyroid from malignant breast, melanoma, and renal cell carcinomas are easily identified by the Afirma GEC
  • Once the test fails to identify one of these rare tumors, the GEC evaluates the expression of 142 genes that are used in a proprietary mathematical algorithm to categorize indeterminate thyroid nodule as either:
    • GEC benign or GEC suspicious
  • The Afirma GEC is founded on the quantification of messenger ribonucleic acid (mRNA) expression
    • There are quite a few diagnostic benefits to using RNA instead of other approaches such as microRNA expression or DNA mutations:
      • The BRAF V600E mutation which is the most common genomic alteration identified in differentiated thyroid cancers, it is usually not identified in cytologically indeterminate thyroid nodules (Bethesda III and IV)
      • The most common mutation among indeterminate thyroid nodules are RAS mutations, but these are identified in both malignant and benign nodules
      • Since benign nodules out-number malignant nodules 4:1 among indeterminate nodules, the PPV of RAS mutations is poor in a multiple of studies
      • The difficulties of using mutational approaches for indeterminate or suspicious thyroid nodules is that many malignancies do not have the known genomic aberrations, and when present, most genomic anomalies are not specific for cancer
  • In the development of the Afirma GEC, instead of discriminately relying on genes formerly detected in the medical literature, analysis of the whole genome (transcriptome) was used to isolate candidate genes, and support vector machine learning methods were used to develop the classifier algorithm
  • The clinical study validating the Afirma GEC was originally performed on a small independent sample of thyroid nodule FNABs within a prospective multicenter, double blind study design
  • The Afirma GEC accomplished a high sensitivity (measures the fraction of cancers that it identifies as positive) and NPV (measures the fraction of “negative” calls by the test (Afirma GEC benign) that are correct), including among indeterminate thyroid nodules
  • The GEC was validated in a second larger independent sample in a prospective multicenter study which included the largest ever prospectively collected set of thyroid FNAB biopsies from 3789 unique patients, with a final validation set of 265 indeterminate nodules
  • Based on the 24% prevalence of malignancy in cytologically indeterminate samples (Bethesda III/IV), a 95% NPV for the Afirma GEC was attained
  • The distinctive and often unnoticed strength of this prospective, multicenter, and blinded validation design is that it supports generalizability of the results
  • The prospective and multicenter study design reduces selection bias and enhances what is likely to occur in the real-world
  • The patients (3789) were prospectively consented and enrolled in the trial before undergoing FNAB at 49 study sites, including academic and community practices, which offers confidence in the external validity of the findings
  • A strong internal validity was established when no differences were found between the final validation cohort of 265 patients compared to the full prospective and consecutive total enrollment cohort
  • The investigators were blinded to the Afirma GEC results, impeding them from being influenced in the decision of which surgery should be recommended
  • These vital study design elements support the internal and external validity of the Afirma GEC study and provide confidence in the broader generalizability of the study findings to every day clinical practice
  • The pre-test risk of malignancy (ROM) determines the PPV and NPV of the Afirma GEC
  • To practice personalized medicine, it is central to consider the individual patient’s pre-test risk
  • The patient’s pre-test ROM includes their individual characteristics (gender, history of childhood radiation, imaging findings, serum TSH among others) and the interpreting cytopathologist’s thresholds to use cytology indeterminate categories
  • Neglecting this very vital step of personalized care and believing that every patient has the same pre-test risk overlooks very important medical information
  • The ATA guidelines allow for either thyroid lobectomy or near-total/total thyroidectomy for thyroid malignancy 1 cm to 4 cm in size without gross extra-thyroidal extension or clinical evidence of lymph node metastases
  • Therefore, numerous factors must be taken into consideration when planning the operation for indeterminate thyroid nodules, such as the risks and benefits, the presence of significant contralateral nodules, long-term follow-up, the role for completion thyroidectomy with or without radioactive iodine ablation if malignancy is found, and patient wishes
  • The 2015 ATA guideline emphasizes ultrasound characteristics to predict the nodule’s ROM
  • The Afirma GEC is anticipated to identify 90% of cancers (sensitivity) as GEC suspicious, and 52% of the benign nodules as GEC benign (specificity), regardless of the pre-test ROM
  • High suspicion ultrasound patterns may be related with a greater than 70% ROM and are found in the minority of nodules with indeterminate cytology
  • Thyroid nodules with such a high pre-test ROM, the NPV of Afirma is expected to be less than 70%, so it may not be useful to avoid surgery in such cases

Bethesda 0 Result What to Do?

We do not have to wait three months to repeat the Ultrasound guided FNA. NO risk of increased atypia.

Bethesda III Thyroid Nodules

Atypia of Undetermined Significance (AUS) or Follicular Lesion of Undetermined Significance (FLUS) on Cytology

  • Based on the Bethesda system:
    • This diagnostic category is reserved for specimens that contain cells with architectural and / or nuclear atypia that are more prominent than expected for benign changes, but not sufficient to be placed in one of the highest-risk diagnostic categories
  • In the studies that used the criteria established by the Bethesda system, the risk of cancer for patients with AUS / FLUS who underwent surgery was:
    • 6% to 18% if NIFT (non-invasive follicular thyroid neoplasia with papillary nuclear characteristics) it is not considered cancer
    • 10% to 30% if NIFT is considered a cancer
  • For thyroid nodules with AUS / FLUS cytology after a FNAB, with clinical and ultrasonographic features of concern:
    • The assessment can be continued by repeating the FNAB or if the technology is available, molecular tests can be used to complement the risk assessment of malignancy instead of preceding directly with a strategy of either surveillance or diagnostic surgery (lobectomy)
  • Patient preference should be considered in decision-making (recommendation 15 of the ATA)
  • If FNAB is not repeated, and molecular tests are not performed, or both studies were inconclusive:
    • A diagnostic surgical excision may be performed for the thyroid nodules with Bethesda AUS / FLUS classification, according to the clinical risk factors, the ultrasonographic pattern, and patient preference (recommendation 15 of the ATA)

Male Breast Cancer

Male breast cancer accounts for less than 1% of all breast cancers but it does behave in a similar way to postmenopausal breast cancer in women.

Male breast cancer does not have a worse biology or prognosis then female breast cancer, males just tend to present at later stages and therefore have worse overall survival.

Approximately a third of men will present with stage III disease.

Approximately 4% to 40% of male breast cancers result from BRCA mutations.

The first step in treatment of male breast cancer is surgical excision.

Men should have mastectomy because the small amount of breast tissue is not conducive to breast conservation. Sentinel node biopsy should be performed and followed by axillary dissection only if the sentinel node is tumor-positive; axillary node dissection is not required in all male patients. It is important to note, however, that the ACOSOG Z011 randomized trial did not include men, so omission of completion axillary dissection for a tumor-positive sentinel node is not recommended.

Adjuvant therapy for male breast cancer is similar to that for female breast cancer. Radiation therapy should be administered for larger tumors with multiple tumor positive nodes. Men can receive hormone therapy if the tumor is estrogen receptor (ER)-positive and studies have shown that hormone therapy improves disease-free and overall survival for men. It is not known if aromatase inhibitors improve survival for men because most of the studies involving men have used tamoxifen. Similarly, the indications for adjuvant chemotherapy are similar to those for women but whether taxanes or dose-dense regimens should be administered is not known. In general, guidelines regarding chemotherapy use for women are used for men.

Fentiman IS, Forquet A, Hortobagyi GN. Male breast cancer. Lancet. 2006;367:595-604.

Giordano SH, Cohen DS, Buzdar AU, Perkins G, Hortobagyi GN. Breast carcinoma in men: a population-based study. Cancer. 2004;101:51-57.

Giordano SH, Perkins GH, Broglio K, et al. Adjuvant systemic therapy for male breast carcinoma. Cancer. 2005;104:235-264.

Goss PE, Reid C, Pintilie M, Lim R, Miller N. Male breast carcinoma: a review of 229 patients who presented to the Princess Margaret Hospital during 40 years: 1955-1996. Cancer. 1999;85:629-639.

Meijer-van Gelder ME, Look MP, Bolt-de Vries J, Peters HA, Klijn JG, Foekens JA. Clinical relevance of biologic factors in male breast cancer. Breast Cancer Res Treat. 2001;68:249-260.

While BRCA1 and BRCA2 are well known to be associated with breast cancer risk, a number of other genetic mutations also increase the risk of this disease.

High-penetrance genes include PTEN and p53. Other mutations such as those in CHEK2, ATM, and PALB2 are associated with moderate risk.

While the development of large-panel testing has allowed for the detection of many mutations that may be associated with increased risk, some are of very low penetrance. For example, STK11 was found to be associated with a pathogenic mutation in 0.01% of breast cancers.

Filippini SE, Vega A. Breast cancer genes: beyond BRCA1 and BRCA2. Front Biosci (Landmark Ed). 2013;18:1358-1372.

Lerner-Ellis J, Khalouei S, Sopik V, Narod SA. Genetic risk assessment and prevention: the role of genetic testing panels in breast cancer.

Expert Rev Anticancer Ther. 2015;15:1315-1326.