INFLAMMATORY BREAST CANCER: DOES ROUTINE AXILLARY SAMPLING HAVE PROGNOSTIC VALUE?
Introduction: As surgical treatment of breast has deescalated on almost all fronts, one treatment has remained constant, and that is the treatment of nonmetastatic inflammatory breast cancer (IBC). Modified radical mastectomy remains the standard of care. Questions remain unanswered. In clinical N0 (cN0) patients is sentinel node biopsy appropriate and might it be eliminated completely given that all will receive comprehensive chest wall radiation (e.g. AMAROS trial)? This study by Grova et al. from the University of North Carolina does not attempt to answer these questions but examines the prognostic value of axillary staging on prognosis in IBC. In doing so however, the data presented from this large study gives one pause about full axillary node dissection (ALND) in selected patients with IBC.
The patients in this study were identified from the National Cancer Database (NCDB). Patients with nonmetastatic IBC (T4d) were identified between the years 2012 and 2016. The authors identified 5265 patients with nonmetastatic IBC. Median follow-up was 32.3 months. Tumor subtypes were as follows: HR+/HER2- (37%), triple negative (26%), HR+/HER2+ (19%), HER-/HER2+ (18%), and 0.6% unclassified due to missing data. Ninety percent received chemotherapy, while only 61% of the total received neoadjuvant chemotherapy (NAC) followed by surgery.
For all patients, the 5-year overall survival was 51.6%. When considering each subtype, the 5-year survival irrespective of treatment was: 51.6% for HR+/HER2-, 72.8% HER+/HER2+, 60.4% HR-/HER2+ and, 34.4% among triple negative women. Not unexpected, in those women undergoing NAC, pathologically node-positive disease was associated with an increase in 5-year mortality. In those women with HER2+ disease 5-year survival dropped from 90% to 66%. In women with triple negative cancer, survival decreased from 73% to 24%. In those with HER+/HER2- survival dropped from 70% to 53%. Most significantly, the authors were unable to discern a patient population with a low enough risk of complete axillary node response to omit pathological axillary assessment.
Pathologic nodal positivity among women who underwent neoadjuvant chemotherapy and breast surgery, stratified by subtype, and clinical nodal status, n = 3167
Comment As noted in the bar graph above, a substantial number of patients in this study receiving NAC had pathologically negative axillary lymph nodes, even when originally having clinically positive nodes. Kell and Morrow reviewed multiple series of IBC in 2006 and concluded that modified radical mastectomy should continue to be the standard surgical therapy following NAC. However, the trials they examined were orders of magnitude smaller than the study by Grova et.al. Based on the AMAROS and other smaller trials it would not seem unreasonable to offer these patients in a trial or registry setting, radiation therapy alone, with or without sentinel node biopsy or targeted axillary node dissection.