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• All patients with HER2 positive breast cancer who require systemic therapy:
  • Should complete 1 year of HER2-targeted therapy:
    • Including those who achieve pathologic complete response after neoadjuvant chemotherapy
• One could also consider continuing adjuvant pertuzumab in addition to trastuzumab based on results from the phase III Aphinity trial:
  • Although patients who received neoadjuvant chemotherapy were not included in this trial
• For patients who have residual disease and do not achieve complete pathologic response at the time of surgery:
  • Completion of 1 year of T-DM1:
    • Decreased the risk of recurrence of invasive breast cancer or death by 50% than with trastuzumab alone:
      • Based on results from KATHERINE trial
    • The estimated percentage of patients who were free of invasive disease at 3 years was 88.3% in the T-DM1 group and 77.0% in the trastuzumab group

References

1. von Minckwitz G, Procter M, de Azambuja E, Zardavas D, Benyunes M, Viale G, et al. Adjuvant Pertuzumab and Trastuzumab in early HER2-positive breast cancer N Engl J Med. 2017;377(2):122-131.

2. von Minckwitz G, Huang CS, Mano MS, Loibl S, Mamounas EP, Untch M, et al. Trastuzumab emtansine for residual invasive HER2-positive breast cancer. N Engl J Med. 2019;380(7):617-628.

• Four large randomized controlled trials:
  • Have set the stage for the treatment of early-stage HER-2 positive breast cancer with HER-2 targeted therapy in the adjuvant setting
• Trastuzumab in the adjuvant setting:
  • Was found to improve disease-free (DFS) and overall survival (OS):
    • As a result, it has become the standard of care in this patient group
  • Treatment with trastuzumab is generally well tolerated:
    • However, one of the main concerns with trastuzumab use has been:
      • The risk of cardiomyopathy
• The North Central Cancer Treatment Group (NCCTG) trial N9831 and the National Surgical Adjuvant Breast and Bowel Project (NSABP) B31 trial:
  • Were first reported by Romond and colleagues in 2005 in a joint analysis
• The N9831 trial:
  • Compared three groups:
    • Group A receiving doxorubicin (Adriamycin [A]) and cyclophosphamide (C) followed by weekly paclitaxel (Taxol [T]) (AC® T)
    • Group B receiving the same regimen followed by 52 weeks of trastuzumab (Herceptin [H]) (AC® T® H)
    • Group C receiving AC followed by 52 weeks of trastuzumab beginning on day 1 of paclitaxel therapy (AC®TH)
• The NSABP B-31 trial:
  • Group 1:
    • Compared doxorubicin and cyclophosphamide followed by paclitaxel every 3 weeks
  • Group 2:
    • The same regimen plus 52 weeks of trastuzumab
• The combined analysis compared:
  • Groups 1 and A (as the control group) and groups 2 and C (as the treatment group). Group B was not analyzed in this joint analysis
  • The studies were terminated early:
    • At a median follow-up of 2 years
  • The combined analysis found that treatment with trastuzumab resulted in:
    • A 52% reduction in the DFS event rate (p < .001) and a 33% early improvement in OS (p = .015)
    • The overall DFS at 3 years, presented in 2007:
      • Was 87.1% in the trastuzumab group compared with 75.4% in the control group
    • In addition, treatment with trastuzumab resulted in a 33% reduction (p = .015) in the risk of death at 4 years
    • With additional follow-up, the most recent analysis, performed with a median follow-up time of 8.4 years:
      • Demonstrated that trastuzumab in addition to chemotherapy led to:
        • Improvement in OS with a risk reduction of 37% and continued substantial improvement in DFS with a risk reduction in disease events of 40%
      • Improvements in OS and DFS were observed in all subgroups of patients with resected HER-2-positive breast cancer:
        • This included small or large tumors, hormone receptor positive or hormone receptor negative, low or high number of involved axillary nodes, and younger or older patients)
      • The risk of a cardiac event in these trials:
        • Ranged from 2.5 to 4%
  • In an attempt to improve efficacy while minimizing cardiotoxicity:
    • Slamon and colleagues compared two anthracycline-containing regimens with a nonanthracycline regimen
    • The Breast Cancer International Research Group (BCIRG) 006 trial, which enrolled 3,222 women with HER-2-positive, node-positive, or high-risk node-negative disease:
      • Compared three-weekly AC followed by docetaxel, with or without trastuzumab, and docetaxel, carboplatin, plus trastuzumab and found that both trastuzumab-containing regimens:
        • Resulted in an improved OS compared with chemotherapy alone
      • Patients who received trastuzumab concurrently with docetaxel following treatment with AC experienced a 51% lower risk of relapse than those receiving docetaxel alone (p < .0001)
      • Patients receiving docetaxel in combination with carboplatin and trastuzumab experienced a 39% lower risk of relapse (p = .0002)
      • The nonanthracycline group:
        • Reported lower cardiac toxicity rates
      • In the control group, grade 3 or 4 congestive heart failure (CHF) was noted in 0.3% of patients compared with 1.6% in the group receiving AC followed by docetaxel plus trastuzumab and 0.4% in the group receiving docetaxel in combination with carboplatin and trastuzumab
• The appropriate treatment duration of trastuzumab remains a subject of interest:
  • The Herceptin Adjuvant (HERA) trial:
    • Compared 1 or 2 years of adjuvant trastuzumab with observation in women with HER-2-positive early-stage breast cancer who had completed adjuvant or neoadjuvant chemotherapy (NAC), surgery, and /or radiation
    • Trastuzumab was initiated at the completion of chemotherapy, radiation, or definitive surgery and was administered every 3 weeks
    • This study of 5,102 women with HER-2-positive early breast cancer showed that trastuzumab for 1 year following chemotherapy improved DFS
    • No difference in outcome was noted between the 1- and 2-year arms
    • At the most recent analysis of the trial:
      • There was no difference in DFS at a median follow-up of 8 years (HR 0.99; 95% CI 0.85 to 1.14; p = .86)
    • In comparison with observation, trastuzumab demonstrated:
      • A superior outcome in terms of both DFS and OS (HR 0.76; 95% CI 0.67 to 0.86; p < .0001 and HR 0.76; 95% CI 0.65 to 0.88; p = .0005, respectively)
    • Severe CHF was recorded in 0% of controls and 0.6% of trastuzumab-treated patients
• The FinHer (Finland Herceptin) trial:
  • Was a small trial that included 232 patients with HER-2-positive disease
  • A total of 116 women were randomized to receive trastuzumab (9 weeks)
  • At a median follow-up of 3 years:
    • DFS was significantly improved (HR 0.42; 95% CI 0.21 to 0.83; p= .01)
• Furthermore, a subsequent trial, PHARE (Protocol for Herceptin as Adjuvant therapy with Reduced Exposure), of a shorter duration of trastuzumab (6 months compared with 1 year):
  • Failed to show the noninferiority of 6 months of treatment as a result of fewer than anticipated events
  • Furthermore, the study noted a significantly higher rate of cardiac events in the 12-month group compared with the 6-month group (5.7% versus 1.9%, p < .0001)
• One year of trastuzumab is the current standard of care for patients with HER-2-positive disease treated with anti-HER-2 therapy

• The development of the monoclonal antibody trastuzumab (Herceptin):
  • Has revolutionized the treatment of patients with HER-2-positive breast cancer
• The exact mechanism of action of trastuzumab remains unclear:
  • It is postulated that its action includes:
    • Antibody-dependent cellular toxicity
    • Inhibition of cell cycle progression
      • Anti-angiogenic effects
• The use of trastuzumab was first approved by the Food and Drug Administration (FDA) in 1998:
  • For the treatment of HER-2-positive metastatic disease:
    • Since that time, drug testing progressed to the adjuvant and neoadjuvant settings
• Today, trastuzumab is regarded as the standard of care for patients with HER-2-positive breast cancer
• Other agents include:
  • The small-molecule tyrosine kinase inhibitor lapatinib and newer drugs, including pertuzumab, trastuzumab-emtansine, neratinib, and ertumaxomab

• The evaluation of HER-2:
  • Is recommended in all cases of breast cancer at the time of initial diagnosis and / or at the time of recurrence to guide therapy
• A number of methods are used for HER-2 testing. including
  • Immunohistochemistry (IHC)
  • Florescence in situ hybridization (FISH)
  • Enzyme-linked immunosorbent assay (ELISA) analysis of serum and tumor
  • Western blot
  • Southern blot
  • Chromogenic in situ hybridization (CISH)
  • Silver in situ hybridization (SISH)
  • Polymerase chain reaction (PCR)
• IHC and FISH:
  • Are currently the main testing modalities for HER-2-positive breast cancer
• HER-2 expression in breast cancer:
  • Is primarily assessed semiquantitatively by IHC
• The 2013 American Society of Clinical Oncology (ASCO) and the College of American Pathologists (CAP) guidelines:
  • Outline an IHC scoring method based on four classes:
    • 0
    • 1+
    • 2+
    • 3+
  • A score of 0 is negative:
    • Indicating no observed staining in invasive tumor cells
  • A score of 1+ is negative:
    • Indicates weak, incomplete membrane staining in any proportion of invasive tumor cells or weak, complete membrane staining in less than 10% of invasive tumor cells
  • A score of 2+ is equivocal:
    • Indicating circumferential membrane staining that is incomplete and / or weak / moderate and in more than 10% of invasive tumor cells or complete and circumferential membrane staining that is intense and in 10% or less of invasive tumor cells
    • All 2+ equivocal cases undergo subsequent testing by FISH
  • A score of 3+ is positive:
    • Indicates circumferential membrane staining that is complete and intense in a homogeneous and contiguous population, present in more than 10% of invasive tumor cells, and readily appreciated using a low-power objective
• FISH is a sensitive and accurate method of scoring invasive breast tumor tissue for HER-2 expression:
  • Initial gene amplification studies by FISH assessment used chromosome 17 centromere (CEP17) or another gene on the same chromosome as an internal control:
    • With a ratio of 2.0 or greater considered evidence of HER-2 amplification:
      • These criteria were used as the cutoff for enrollment in trials evaluating HER-2 targeted therapies
  • In 2007, the ASCO / CAP guidelines were changed to define HER-2 amplified as:
    • A ratio of 2.2 or greater
• More recent guidelines have changed the ratio cutoff back to:
  • A ratio of 2.0 or greater with the inclusion of criteria to account for HER-2 copy number per tumor cell:
    • Based on the recent guidelines, HER-2 is amplified in cases where the HER-2 / CEP17 ratio is 2.0 or greater with an average HER-2 copy number of more than 4.0 signals/cell or the HER-2 / CEP17 ratio is less than 2.0 with an average HER-2 copy number of 6.0 or more signals/cell using a dual probe or a HER-2 copy number of 6.0 or more copies/cell using a single probe
  • FISH testing is negative for HER-2 amplification with a HER-2 / CEP17 ratio of less than 2.0 with an average HER-2 copy number of less than 4.0 signals/cell or an average HER-2 copy number of less than 4.0 signals/cell using a single probe

• Per American Society of Clinical Oncology / College of American Pathologists (ASCO/CAP) guidelines:
  • Tumors with an immunohistochemical result of 2+ (equivocal):
    • HER2 / CEP17 ratio of > 2.0 and copy number of > 4.0:
      • Are considered positive

References

1. Wolff AC, Hammond MEH, Allison KH, Harvey BE, Mangu PB, Bartlett JMS, et al. Human epidermal growth factor receptor 2 testing in breast cancer: American Society of Clinical Oncology/College of American Pathologists Clinical Practice Guideline focused update. J Clin Oncol. 2018;142(11):1364-1382.

2. Lin L, Sirohi D, Coleman JF, Gulbahce HE. American Society of Clinical Oncology/College of American Pathologists 2018 focused update of breast cancer HER2 FISH testing guidelines. results from a National Reference Laboratory. Am J Clin Pathol. 2019;152(4):479-485

• MCC is a rare neuroendocrine malignancy of the skin:
  • Predominately affecting older white individuals:
    • It commonly arises in sun-exposed areas such as the head, neck, and extremities
• The incidence of MCC is very low when compared to other cutaneous malignancies:
  • With an estimated 1,500 cases diagnosed annually within the United States.
• In 1875, Friedrich Sigmund Merkel:
  • Described large, pale cells in the basal layer of the epidermis:
    • Forming synapse-like contacts with enlarged nerve terminals (mechanoreceptors)
• In 1972, Toker described a trabecular carcinoma of the skin:
  • Thought to have derived from sweat glands
    • These cells, now known as Merkel cells, resemble cells of the diffuse neuroendocrine system or the amine precursor uptake decarboxylation system
• The clinical and pathologic diagnosis of MCC can be challenging, especially when it presents as a nodal metastasis:
  • Because as a small round blue cell it can be difficult to differentiate from other undifferentiated small-cell neoplasms of different primary origin such as the lung
• The diagnosis of MCC of a primary lesion by using hematoxylin and eosin staining:
  • Should be further confirmed by immunohistochemistry (IHC) staining
• CK20 is a sensitive marker for MCC:
  • It is positive in 89% to 100% of cases
• TTF-1 is expressed in 83% to 100% of small-cell lung cancer:
  • But is negative for MCC
• Other IHC markers such as chromogranin A, synaptophysin, neurofilament protein, CD56, and neuron-specific enolase may be used in addition to CK20 and TTF-1 to exclude other diagnoses
• When patients present with clinically positive nodal disease in the absence of a history of an identifiable primary tumor, and the tumor fulfills the diagnostic pathologic criteria:
  • It is known as MCC of unknown primary origin (MCCUP):
    • The incidence of MCCUP presenting in the nodal basins has been described in case reports in the literature as ranging from 2% to 19% of all cases of MCC
    • The exact origin of MCCUP is unknown, but several theories have been postulated, including:
      • Incorrect or misdiagnosis of a previously excised cutaneous tumor
      • Spontaneous regression of a primary MCC lesion
      • Immunosuppression:
        • Transplant recipients
        • Lymphoproliferative disorders
        • Human immunodeficiency virus [HIV] infection
      • MCC arising from a mucosal origin
      • The small double-stranded DNA polyomavirus (Merkel cell polyomavirus)
• The treatment of MCC:
  • Is stage-dependent
• A multidisciplinary panel:
  • Is recommended to assure appropriate treatment of this rare and challenging disease
• Surgery:
  • Is the primary treatment modality for MCC
  • For patients with a cutaneous lesion in the absence of clinical lymphadenopathy:
    • The recommendation is for wide excision with a 1 to 2 cm margin and SLN biopsy
• Adjuvant radiation therapy to the primary tumor site is generally recommended:
  • Unless the primary tumor is small (less than 1cm)
  • Widely excised
  • And without other risk factors such as:
    • Lymphovascular invasion
    • Immunosuppression
• If SLN biopsy is negative for metastasis:
  • Adjuvant radiation therapy to the regional nodes is generally avoided
• Regional lymph node dissection is recommended when nodal micrometastasis is identified by SLN biopsy:
  • Generally without adjuvant nodal irradiation (although nodal radiation therapy may be considered in high-risk cases)
• For patients who present with clinical lymphadenopathy:
  • The recommendation is for confirmation with fine-needle aspiration or core-needle biopsy
• Imaging studies, including computer tomography, magnetic resonance imaging, or positron-emission tomography, are performed to rule out visceral involvement followed by nodal dissection and / or radiation therapy
• In the presence of distant metastasis:
  • Multidisciplinary tumor board evaluation is recommended with best supportive care or any combination of chemotherapy, radiation and / or surgery.
• The 5-year survival for clinically node-negative patients with localized disease is 75%
• Patients with lymph node metastases and distant metastases fairing worse, with 59% and 25% 5-year survival rates, respectively
• Recurrences are most likely to occur within two years of diagnosis of the primary tumor
• The outcome of patients with MCCUP is perhaps slightly better than stage III MCC patients with known primary tumors based on retrospective data
• References:
  • Allen P, Bowne W, Jaques D, et al. Merkel cell carcinoma: prognosis and treatment of patients from a single institution. J Clin Oncol. 2005;23(10):2300-2309.
  • Feng H, Shuda M, Chang Y, et al. Clonal integration of a polyomavirus in human Merkel cell carcinoma. Science. 2008;319:1096-1100.
  • Heath M, Jaimes N, Lemos B, et al. Clinical characteristics of Merkel cell carcinoma at diagnosis in 195 patients: the AEIOU features. J Am Acad Dermatol. 2008;58:375-381.
  • Merkel cell carcinoma, Chapter 30. In: Edge SB, Byrd DR, Compton CC, Fritz AG, Greene FL, Trotti A. eds. AJCC Cancer Staging Manual. 7th ed. New York: Springer; 2009: 315-323.
  • National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology. Merkel Cell Carcinoma. Available at http://www.nccn.org.
  • Toker C. Trabecular carcinoma of the skin. Arch Dermatol. 1972;105:107-110.

• MCC is a rare neuroendocrine malignancy of the skin:
  • Predominately affecting older white individuals:
    • It commonly arises in sun-exposed areas such as the head, neck, and extremities
• The incidence of MCC is very low when compared to other cutaneous malignancies:
  • With an estimated 1,500 cases diagnosed annually within the United States.
• In 1875, Friedrich Sigmund Merkel:
  • Described large, pale cells in the basal layer of the epidermis:
    • Forming synapse-like contacts with enlarged nerve terminals (mechanoreceptors)
• In 1972, Toker described a trabecular carcinoma of the skin:
  • Thought to have derived from sweat glands
    • These cells, now known as Merkel cells, resemble cells of the diffuse neuroendocrine system or the amine precursor uptake decarboxylation system
• The clinical and pathologic diagnosis of MCC can be challenging, especially when it presents as a nodal metastasis:
  • Because as a small round blue cell it can be difficult to differentiate from other undifferentiated small-cell neoplasms of different primary origin such as the lung
• The diagnosis of MCC of a primary lesion by using hematoxylin and eosin staining:
  • Should be further confirmed by immunohistochemistry (IHC) staining
• CK20 is a sensitive marker for MCC:
  • It is positive in 89% to 100% of cases
• TTF-1 is expressed in 83% to 100% of small-cell lung cancer:
  • But is negative for MCC
• Other IHC markers such as chromogranin A, synaptophysin, neurofilament protein, CD56, and neuron-specific enolase may be used in addition to CK20 and TTF-1 to exclude other diagnoses
• When patients present with clinically positive nodal disease in the absence of a history of an identifiable primary tumor, and the tumor fulfills the diagnostic pathologic criteria:
  • It is known as MCC of unknown primary origin (MCCUP):
    • The incidence of MCCUP presenting in the nodal basins has been described in case reports in the literature as ranging from 2% to 19% of all cases of MCC
    • The exact origin of MCCUP is unknown, but several theories have been postulated, including:
      • Incorrect or misdiagnosis of a previously excised cutaneous tumor
      • Spontaneous regression of a primary MCC lesion
      • Immunosuppression:
        • Transplant recipients
        • Lymphoproliferative disorders
        • Human immunodeficiency virus [HIV] infection
      • MCC arising from a mucosal origin
      • The small double-stranded DNA polyomavirus (Merkel cell polyomavirus)
• The treatment of MCC:
  • Is stage-dependent
• A multidisciplinary panel:
  • Is recommended to assure appropriate treatment of this rare and challenging disease
• Surgery:
  • Is the primary treatment modality for MCC
  • For patients with a cutaneous lesion in the absence of clinical lymphadenopathy:
    • The recommendation is for wide excision with a 1 to 2 cm margin and SLN biopsy
• Adjuvant radiation therapy to the primary tumor site is generally recommended:
  • Unless the primary tumor is small (less than 1cm)
  • Widely excised
  • And without other risk factors such as:
    • Lymphovascular invasion
    • Immunosuppression
• If SLN biopsy is negative for metastasis:
  • Adjuvant radiation therapy to the regional nodes is generally avoided
• Regional lymph node dissection is recommended when nodal micrometastasis is identified by SLN biopsy:
  • Generally without adjuvant nodal irradiation (although nodal radiation therapy may be considered in high-risk cases)
• For patients who present with clinical lymphadenopathy:
  • The recommendation is for confirmation with fine-needle aspiration or core-needle biopsy
• Imaging studies, including computer tomography, magnetic resonance imaging, or positron-emission tomography, are performed to rule out visceral involvement followed by nodal dissection and / or radiation therapy
• In the presence of distant metastasis:
  • Multidisciplinary tumor board evaluation is recommended with best supportive care or any combination of chemotherapy, radiation and / or surgery.
• The 5-year survival for clinically node-negative patients with localized disease is 75%
• Patients with lymph node metastases and distant metastases fairing worse, with 59% and 25% 5-year survival rates, respectively
• Recurrences are most likely to occur within two years of diagnosis of the primary tumor
• The outcome of patients with MCCUP is perhaps slightly better than stage III MCC patients with known primary tumors based on retrospective data
• References:
  • Allen P, Bowne W, Jaques D, et al. Merkel cell carcinoma: prognosis and treatment of patients from a single institution. J Clin Oncol. 2005;23(10):2300-2309.
  • Feng H, Shuda M, Chang Y, et al. Clonal integration of a polyomavirus in human Merkel cell carcinoma. Science. 2008;319:1096-1100.
  • Heath M, Jaimes N, Lemos B, et al. Clinical characteristics of Merkel cell carcinoma at diagnosis in 195 patients: the AEIOU features. J Am Acad Dermatol. 2008;58:375-381.
  • Merkel cell carcinoma, Chapter 30. In: Edge SB, Byrd DR, Compton CC, Fritz AG, Greene FL, Trotti A. eds. AJCC Cancer Staging Manual. 7th ed. New York: Springer; 2009: 315-323.
  • National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology. Merkel Cell Carcinoma. Available at http://www.nccn.org.
  • Toker C. Trabecular carcinoma of the skin. Arch Dermatol. 1972;105:107-110.

• What do you discuss with your patients as potential adverse effects of these HER2-targeted therapies?
  • Trastuzumab and pertuzumab can cause decrease in ejection fraction in up to 20% of patients:
    • Although this is often reversible
  • Trastuzumab can less commonly cause pneumonitis
  • Pertuzumab can cause rash and diarrhea

References

1. Gianni L, Pienkowski T, Im YH, Roman L, Tseng LM, Liu MC, et al. Efficacy and safety of neoadjuvant pertuzumab and trastuzumab in women with locally advanced, inflammatory, or early HER2-positive breast cancer (NeoSphere): a randomised multicentre, open-label, phase 2 trial. Lancet Oncol. 2012;13(1):25-32.

2. Schneeweiss A, Chia S, Hickish T, Harvey V, Eniu A, Hegg R, et al. Pertuzumab plus trastuzumab in combination with standard neoadjuvant anthracycline-containing and anthracycline-free chemotherapy regimens in patients with HER2-positive early breast cancer: a randomized phase II cardiac safety study (TRYPHAENA). Ann Oncol.2013;24(9):2278-2284.

Type II error refers to the acceptance of the null hypothesis in a study when the null hypothesis is actually incorrect

Type I error occurs when the null hypothesis is rejected although it is true

Type III error occurs when the null hypothesis is rejected but the wrong assumptions are used

Random error is defined as errors that occur in experimental measurements secondary to unknown and unpredictable changes in the experimental conditions

Variance error is defined as all sources of variability in an experiment that are not subject to investigation.

References

Harvey BJ, Lang TA. Hypothesis testing, study power, and sample size. Chest. 2010;138:734-737.

Wuensch K. Type III errors. Available at
http://core.ecu.edu/psyc/wuenschk/stathelp/Type_III.htm

Exell RHB. Random vs systematic error. Available at http://www.physics.umd.edu/courses/Phys276/Hill/Information/Notes/ErrorAnalysis.html

Per current guidelines, a positive margin with an invasive carcinoma requires re-excision.

After reduction and with an unoriented specimen, it would not be possible to safely determine which margin to re-excise. Thus, mastectomy is the standard answer for management.

Moran MS, Schnitt SJ, Giuliano AE, et al. Society of Surgical Oncology-American Society for Radiation Oncology Consensus Guideline on Margins for Breast-Conserving Surgery with Whole-Breast Irradiation in Stages I and II Invasive Breast Cancer. J Clin Oncol. 2014; 32(14): 1507-15.