Is there any difference between microscopic residual disease (pTm) and no invasive disease (pT0) in the breast when there is residual disease in the axilla after primary chemotherapy for breast cancer (BC)? Results of a multicenter study

Abstract

11069 Background: Several studies have demonstrated the importance of achieving pCR both in the breast and axilla, in terms of DFS and OS. We previously demonstrated that no difference exists between microscopic residual (pTm) and no invasive residual (pT0) tumour in the breast in terms of DFS and OS in breast cancer (BC) patients (pts) following primary chemotherapy (CHT). Nevertheless, when pN0 is achieved, we observed a statistical significant advantage for pT0 in comparison to pTm pts (DFS 94.7% vs 80%, p=0.03; OS 100% vs 86%, p=0.08). Aim of the present study was to investigate the clinical significance of pTm in the breast when there is residual tumour in the axilla. Methods: We analysed 48 out of 287 pts with clinical T2–4 BC, who achieved pCR, according to Sataloff’s classification, following different kinds of neoadjuvant CHT. One pt was considered not valuable for clinical outcomes, because lost to follow up. Median age was 47 years (29–68), clinical TN stage was T4 in approximately half of the pts (22/48, 45.8%) and N+ in 11/48 (22.9%). Hormone receptor status was ER- in 20 pts (41.7%) and PR- in 26 (54.2%). All pts received anthracycline-based neoadjuvant CHT, even standard (Q21 days) or intensified (Q14). Median number of administered cycles was 3 (2–6). Median follow up was 89 months (9–189). Results: Thirteen pts (27.6%) had residual disease in the axilla at the end of primary CHT, of whom 6 achieved pT0 and 7 pTm in the breast. Surprisingly, pTm pts had a significant better DFS and OS in comparison to pT0 pts. Results are shown in Table 1 . Conclusions: Our data indicate that the achievement of pT0 in the breast is not of clinical significance when there is residual tumour in the axilla. These results, even if affected by the small number of pts, could be explained by the fact that less aggressive treatments have been delivered to pT0 pts due to the complete clearance of the tumour. [Table: see text] No significant financial relationships to disclose.