Abstract P5-16-24: Prognostic factors after neoadjuvant chemotherapy in breast cancer: Surgery type as a new prognostic factor
Authors: Fujihara M , Kin T , Yoshimura Y , Kajiwara Y , Ito M , Ohtani S 
Published: March 2017

Background: Pathological complete response (pCR) after neoadjuvant chemotherapy (NAC) is not necessarily linked to long-term survival. Response to chemotherapy and outcomes after NAC differ among breast cancer subtypes, so we analyzed prognostic factors by subtype.

Methods: We retrospectively analyzed 451 patients treated with anthracycline and taxane-based NAC between 2007 and 2015. Trastuzumab was added for human epidermal growth factor receptor (HER)-2-positive breast cancer. pCR was defined as no residual invasive breast carcinoma; noninvasive residuals and infiltrated lymph nodes were allowed. In our institute, mastectomy was performed in patients in whom the breast could not be preserved, such as patients with large residual tumors and diffusely spread tumors throughout the breast after NAC. Kaplan–Meier and univariate and multivariate cox regression analyses were used to evaluate disease-free interval (DFI) and DFI prognostic values, respectively.

Results: Median follow-up was 43 months; median age was 56 (range, 23–88) years. The 3-year DFI and OS were 82.1% and 94.4%, respectively. In total, 85 patients had recurrence (18.8%) and 31 patients died (6.9%). Response rate (RR) was 93.4% (421/457).pCR rate was 26.2% (118/451) in all cases: 0% (0/82), luminal A; 10.9% (14/128), luminal B HER2(−); 43.1% (31/71), luminal B HER2(+); 59.4% (38/64), HER2; and 34% (36/106), triple negative (TN). For all subtypes, patients who achieved pCR had a non-significantly higher DFI.

Multivariate cox regression showed these associations with DFI: surgery type and Ki-67 &gt; 30% for all cases and luminal B HER2(-); ypN (lymph node status after NAC), luminal B HER2(+);ypN and menopausal status, HER2; and age, surgery type, and clinical lymph node status (cN), TN.

Kaplan–Meier analysis showed that surgery type was strongly associated with DFI after NAC. Mastectomy patients had significantly poorer prognoses than partial mastectomy patients for all subtypes except HER2. For all cases, the median DFI in mastectomy patients was 73 months, but DFI was not reached in partial mastectomy patients (p &lt; 0.0001). Compared with partial mastectomy patients, mastectomy patients had more advanced disease in terms of tumor size, lymph node status, and stage and showed lesser clinical and pathological responses to NAC and effects on ypN. Furthermore, first recurrences in mastectomy patients were often distant metastases, leading to poor prognosis.

Moreover, we analyzed the prognostic factors in 118 patients who achieved pCR. Univariate Cox regression analysis showed the association of the following with DFI: age (≤40, &gt;40), cN, stage, surgery type, and ypN for all cases; decreasing Ki-67 values after NAC, luminal B HER2(−); clinical tumor size (cT), cN, surgery type, and luminal B HER2(+); ypN and HER2; age (≤40, &gt;40), cN, stage, surgery type, and TN. In multivariate cox regression analysis, age (≤40, &gt;40), surgery type, and ypN were independent predicting factors for all cases.

Conclusions: Prognostic factors after NAC differ among subtypes. Surgery type was strongly associated with outcomes after NAC, so it could be an independent prognostic factor.

Citation Format: Fujihara M, Kin T, Yoshimura Y, Kajiwara Y, Ito M, Ohtani S. Prognostic factors after neoadjuvant chemotherapy in breast cancer: Surgery type as a new prognostic factor [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-16-24.