Association of relative dose intensity with BMI and pathologic complete response in patients treated with neoadjuvant...

Previous work found that lower BMI is associated with a pathologic complete response (pCR) following neoadjuvant chemotherapy for breast cancer. Relative dose intensity (RDI) of chemotherapy is an important marker of treatment tolerability. We hypothesized that patients with low BMI would have higher RDI than patients with high BMI, explaining the mechanism for the association between BMI and pCR.

We conducted a retrospective study of women treated with neoadjuvant chemotherapy for stage I-III breast cancer at Yale New Haven Hospital-Smilow Cancer Hospital. We reviewed medical records to determine tumor characteristics, chemotherapy doses, and reasons for dose reductions or delays. The treatment RDI was calculated using published methods. Chi-squared analyses were conducted to determine the associations between RDI and BMI and between RDI and pCR.

Our cohort (n = 237) had an average age of 53 years (SD 13) and mean BMI of 29.5 kg/m² (SD 7.0). Fifty-eight patients (24%) received <85% RDI, and 61% of patients experienced at least one dose reduction or delay. BMI was not associated with RDI (p = 0.71), and RDI was not associated with pCR (p = 0.31); however, fewer dose delays was associated with pCR (p = 0.02). The most common reasons for dose reduction or delays were neuropathy, myelosuppression, and personal reasons.

Nearly one quarter of our cohort had RDI <85%. Although RDI overall was not associated with pCR, having fewer dose delays was associated with pCR. Our results highlight a need for improved patient adherence to and tolerability of neoadjuvant chemotherapy to minimize treatment delays.