Impact of neoadjuvant therapy on eligibility for and frequency of breast conservation in stage II III HER2 positive breast cancer: surgical results of CALGB 40601 (Alliance)
ObjectiveIt had been previously shown that patients who receive neoadjuvant systemic therapy (NST) are more likely to undergo breast conserving therapy (BCT) than those who have primary surgery. However, the frequency with which patients who are not BCT eligible prior to NST convert to BCT eligible with treatment is unknown. To document this conversion rate in a subset of patients expected to have a high clinical response rate to NST, we studied surgical assessment and management of patients enrolled on a randomized neoadjuvant trial for stage II III HER2 positive breast cancer (HER2 BC)(CALGB 40601).MethodsThe treating surgeon assessed BCT candidacy based on clinico radiographic criteria both before and after NST. Definitive breast surgical management was at surgeon and patient discretion. We sought to determine (1) the conversion rate from BCT ineligible to BCT eligible (2) the percentage of BCT eligible patients who chose breast conservation, and (3) the rate of successful BCT. We also evaluated surgeon determined factors for BCT ineligibility and the correlation between BCT eligibility and pathologic complete response (pCR).ResultsOf 292 patients with pre and post NST surgical assessments, 59 were non BCT candidates at baseline. Of the 43 of these patients who converted with NST, 67 opted for BCT, with an 80 success rate. NST increased the BCT eligible rate from 41 to 64 Common factors cited for BCT ineligibility prior to NST including tumor size (56 and probable poor cosmetic outcome (26 were reduced by 67 and 75 respectively, with treatment, while multicentricity, the second most common factor (33 fell by only 16 Since 23 of the BCT eligible patients chose mastectomy, BCT was the final surgical procedure in just 40 of the patients. Patients considered BCT eligible both at baseline and after NST had a pCR rate of 55 while patients who were BCT ineligible prior to NST had the same pCR rate (44 whether they converted to BCT eligible or not.ConclusionsMany patients with HER2 BC deemed ineligible for BCT at baseline can be converted to BCT eligible with NST; excluding patients with multicentric disease substantially increases that percentage. In converted patients who opt for BCT, the success rate is similar to that of patients considered BCT eligible at baseline. Whether a BCT ineligible patient converts to BCT eligibility or not does not appear to affect the likelihood of achieving a pCR. Despite the efficacy of NST in this patient cohort, only 40 of patients had successful BCT; further research into why BCT eligible patients often opt for mastectomy is needed.
Breast Cancer Research and Treatment