Abstract P3-08-39: Pathological complete response following neoadjuvant chemotherapy in operable breast cancer patients: Is obesity a predictive factor?

Abstract

Abstract Background: Overweight and obesity are associated with greater disease-specific mortality and overall mortality in cancer patients. Neoadjuvant chemotherapy offers a unique setting to assess breast cancer chemosensitivity in vivo, and thus can help us understand why obesity is associated with poor prognosis in breast cancer patients. The effect of increased Body mass index (BMI) in breast cancer patients undergoing neoadjuvant chemotherapy remains controversial. Purpose: To review and analyze the association between BMI and pathological complete response (pCR) rate for operable breast cancer after neoadjuvant chemotherapy (NACT). Data sources: Pub Med and Cochrane Database to December 31, 2018 Study selection: We included observational studies and randomized trials that evaluated association of BMI with pCR in operable breast cancer patients that underwent NACT. Data extraction and analysis: Two authors independently extracted data and rated study quality; discrepancies were resolved through consensus. Results: We identified 13 studies including a total of 14179 women with operable breast cancer who underwent NACT. Among them, two studies were pooled analysis of prospective clinical trials (10622 patients); the rest were retrospective case control studies (3557 patients). The influence of categorical BMI on pCR after NACT was analyzed. All studies provided data with BMI divided into two subgroups (BMI <25 vs BMI ≥25). Pooled analyses demonstrated overweight/obese women were less likely to achieve pCR after NACT when compared with women in the under-/normal weight group, OR=0.77 (95% CI: 0.71, 0.84). 10 studies provided data with BMI divided into three groups (BMI <25, 25 ≤BMI< 30, BMI ≥30). Pooled analyses showed compared to under-/normal weight group, both overweight (OR= 0.81 95% CI: 0.72, 0.89) and obese (OR = 0.62 95% CI: 0.54, 0.69) groups were less likely to achieve pCR to NACT. We were not able to perform pooled analysis of association between BMI and pCR in subtypes of breast cancer based on hormone receptor and HER-2 status; as only two studies provided these data and breast cancer subtypes were defined differently. There was moderate heterogeneity in between these studies. Conclusion: Overweight and obese breast cancer patients had lower pCR rates compared to those with under-/normal weight. Further prospective studies may help to confirm this finding and to clarify underlying mechanisms. Citation Format: Haiyun Wang, Shijia Zhang, Douglas Yee, Heather Beckwith, David Potter, Anne Blaes. Pathological complete response following neoadjuvant chemotherapy in operable breast cancer patients: Is obesity a predictive factor? [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-08-39.