Impact of multifocal or multicentric disease on surgery and locoregional, distant and overall survival of 6,134 breast cancer patients treated with neoadjuvant chemotherapy.

Background: The impact of tumor focality on type of surgery, local recurrence rate, and survival after neoadjuvant chemotherapy (NACT) for breast cancer is not fully understood. This study aimed to compare local recurrence-free survival (LRFS), disease-free survival (DFS), and overall survival (OS) according to focality stratified by type of surgery and pathologic complete response (pCR), with a focus on breast conservation.
Methods: Participants (n = 6,134) in the GeparTrio, GeparQuattro, and GeparQuinto trials with operable or locally advanced tumors receiving NACT were classified as having unifocal (1 lesion), multifocal (≥ 2 lesions in 1 quadrant), or multicentric (≥ 1 lesion in ≥ 2 quadrants) disease. The study investigated LRFS, DFS, and OS according to focality stratified by type of surgery and pathologic complete response.
Results: The patients were classified as having unifocal (n = 4,733, 77.1 %), multifocal (n = 820, 13.4 %), or multicentric (n = 581, 9.5 %) tumors. The respective pCR rates were 19.4, 16.5, and 14.4 %. Breast conservation was performed for 71.6, 58.5, and 30 % of these patients, respectively (P < 0.001). The LRFS rate was 92.9 % for the unifocal, 95.1 % for the multifocal, and 90.4 % for the multicentric tumors (P = 0.002). The patients with multicentric tumors but not the patients with multifocal tumors had worse DFS (P < 0.001) and OS (P = 0.009) than the patients with unifocal tumors. However, LRFS, DFS, and OS were not inferior for the patients with multicentric or multifocal tumors if pCR was achieved or breast conservation was performed after NACT.
Conclusion: Breast conservation is feasible for clinically multifocal or multicentric breast cancer patients who undergo NACT without worsening LRFS if tumor-free margins can be attained or if patients achieve a pCR.