High Mitotic Counts after Neoadjuvant Chemotherapy (NAC) Provide Complementary Prognostic Information to Residual Cancer Burden.
Diaz Janice, Stead Lesley, Shapiro Nella, Loudig Olivier, Sparano Joseph, Fineberg Susan. Montefiore Medical Center (MMC) and the Albert Einstein College of Medicine (AECOM), Bronx, NY; MMC & AECOM, Bronx, NY
Background: Patients (pts) with localized invasive breast cancer (IBC) who have a good pathologic response after neoadjuvant chemotherapy (NAC) prior to resection have improved survival. Systems for evaluating pathologic response after NAC include AJCC and Residual Cancer Burden (RCB), which rely on measurements of residual tumor volume in the breast and lymph nodes. We hypothesized that mitotic activity of the residual tumor in the breast post-chemotherapy (PC) may provide additional prognostic information.
Design: We evaluated 38 IBC cases from 37 pts with Her2-negative/Her2-borderline disease who received NAC, which included doxirubicin, cyclophosphamide and paclitaxel. The study population included 16 triple negative, 21 ER + and 1 Her-2 borderline tumor. the authors (SF and/orJD) reviewed H&E stained slides of the PC resected tumor for mitotic count (MC- number of mitoitic figures per 10 high power fields (HPF- field diameter 0.55 mm) and also determined factors required to calculate RCB (www.mdanderson.org/.../calculators-rcb-pathology-protocol2.pdf). We reviewed imaging and laboratory reports.
Results: Ten pts ( 26%, 95% confidence intervals (CI) 16%,47%) had a pathologic complete response in the breast and 10 patients (26%, 95% CI 16%,47%) developed a distant recurrence after a median of 16 months ( range 1-39 months) after starting NAC. For the 28 tumors with residual disease in the breast after NAC, distant recurrence occured in 9 of 14 tumors ( 64%) with a MC> 18 compared with 0 of 14 tumors with a MC <18 (p=0.0006). Distant recurrence occured in 9 of 22 tumors (42%) with an RCB score of III compared with 1 of 16 tumors (6%) with an RCB score of 0-II (p=0.01), When considering both RCB score and MC in the 22 tumors with RCBIII, distant recurrence occurred in 9 of 12 tumors with MC>18 per 10 HPF compared with none of the 10 tumors with MC<18 per 10 HPF (p<0.0001).
Conclusions: Our data suggest that High MC ( >18 per 10 HPF) in residual invasive breast cancer after NAC is significantly associated with an increased risk of distant recurrence and can identify tumors with a high RCB score at highest risk for distant relapse
Tuesday, March 1, 2011 9:30 AM
Poster Session III # 39, Tuesday Morning