Abstract S3-1: Neoadjuvant Chemotherapy in the very young 35 years of age or younger

Abstract Background: In young women the course of breast cancer (BC) tends to be more aggressive. In several trials young age at diagnosis was an independent predictive factor for pathological complete response (pCR) after neoadjuvant chemotherapy. Here we investigate especially the rare entity of very young women at age 35 years or younger. Methods: 8949 patients from 8 neoadjuvant German studies with operable or locally advanced, non-metastatic breast cancer and follow-up were included (for details see von Minckwitz G et al, BCRT 2010 and NEJM 2012). A subgroup of 704 patients of age 35 years or younger was analyzed. All patients with endocrine responsive disease received adjuvant endocrine therapy according to institutional standard. We compared pathological complete remission rate (pCR) defined as ypT0, ypN0 and disease free survival rate (DFS) of this very young group with older patients in total and in different histopathological subgroups (as defined previously by von Minckwitz J Clin Oncol 2012). Results: From 8949/6561 had known ER, PR, HER2 and grading. There were less Luminal A and more TNBC in the very young women compared to the one >35 years of age: Luminal A: 131 (21%) vs. 2251 (27%); Luminal B HER2−: 50 (8%) vs. 783 (10%); Luminal B HER2+: 103 (17%) vs. 989 (14%); HER2+/HR−: 72 (11%) vs. 739 (10%); TNBC: 164 (26%) vs. 1415 (19%). The pCR rate was significantly higher in the very young than in the group older than 35 years (23.6% vs. 15.7.%; p < 0.0001). However, this difference was confined to the TNBC subgroup (45% vs. 31%; OR 1.85; 95%CI [1.33–2.56]; p < 0.001). Only in the triple negative cohort age had independent predictive factors for achieving a. pCR. Compared to patients >35 years, in the very young only hormone receptor status and grading had independent predictive information for pCR but not T-stage and nodal-stage. No difference in DFS according to age was seen when the patients had a pCR. Non-pCR patients had a significantly worse DFS when they were very young (DFS HR: 1.35; p = 0.001). Adjusting for T-stage, nodal-stage, age and pCR; within the TNBC pCR but not age had independent prognostic information for DFS (pCR: HR: 0.18 [95%CI 0.13–0.16]; p < 0.0001; age HR: 1.06 [95%CI 0.74–1.51]; p = 0.77); within the Luminal A group age but not pCR had independent prognostic information for DFS (age: HR 2.5 [95% CI 1.6–3.9] p < 0.001; pCR: HR 0.72 [95%CI 0.37–1.41] p = 0.34). In the Luminal A group the worst DFS was seen in the group <=35years/no-pCR and the best DFS in the <=35 years with pCR (log rank p = 0.27; HR 0.05 wide CI due to small sample size; p = 0.5). Conclusion: Very young women are more likely to achieve a pCR after neoadjuvant chemotherapy. This effect is driven mainly by triple negative BC, which is more common in the very young. Age did not influence DFS in TNBC when a pCR was achieved. It can be hypothesized that the very young pts with Luminal A tumors benefit from a pCR, whereas overall pCR is not a predictor in the Luminal A subgroup. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr S3-1.