BMI Is an Independent Prognostic Factor in Patients With Node-Positive Breast Cancer Receiving Optimally Dosed Chemotherapy
In an analysis reported in the Journal of the National Cancer Institute, Ligibel et al found that body mass index (BMI) at diagnosis was independently prognostic for recurrence-free and overall survival in women with early-stage node-positive breast cancer who received doxorubicin, cyclophosphamide, and paclitaxel dosed by actual body weight in the CALGB 9741/Alliance trial. BMI remained an independent prognostic factor in analysis including PAM50 tumor subtype.
Study Details
Among 2005 patients enrolled in CALGB 9741, baseline height and weight were available for 1,909 and 1,272 had subtype determination by PAM50 using archived specimens. Associations between BMI and PAM50 findings and recurrence-free and overall survival were evaluated by proportional hazards regression adjusting for number of involved nodes, estrogen receptor status, tumor size, menopausal status, drug sequence, and dose density.
BMI as Prognostic Factor
Median follow-up was 11 years. On multivariate analysis, baseline BMI was a significant predictor of recurrence-free survival (adjusted hazard ratio [HR] = 1.08, P = .01, for each 5-unit increase) and overall survival (adjusted HR = 1.08, P = .02, per 5-unit increase). Multivariate analysis showed no significant interactions between estrogen receptor status and BMI for recurrence-free (P = .87) or overall survival (P = .53).
In an exploratory analysis including PAM50 subtype, BMI was a significant prognostic factor for recurrence-free survival (HR = 1.12, P = .01, per 5-unit increase). There was no significant interaction between BMI and PAM50 subtype (P = .15). Unadjusted HRs per 5-unit increase in BMI were 1.23 (95% confidence interval [CI] = 1.08–1.40) for luminal A (n = 403), 1.00 (95% CI = 0.87–1.16) for luminal B (n = 334), 1.10 (95% CI = 0.97–1.26) for HER2-enriched (n = 251), and 1.11 (95% CI = 0.97–1.28) for basal-like (n = 284) subgroups.
The investigators concluded: “BMI at diagnosis was a statistically significant prognostic factor in a group of patients receiving optimally dosed chemotherapy. Additional research is needed to determine the impact of weight loss on breast cancer outcomes and to evaluate whether this impact is maintained across tumor subtypes.”
Jennifer A. Ligibel, MD, of Dana-Farber Cancer Institute, is the corresponding author for the Journal of the National Cancer Institute article.
The study was supported by the Breast Cancer Research Foundation, National Cancer Institute Strategic Partnering to Evaluate Cancer Signatures (SPECS) Program, and National Cancer Institute grants.
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