Body mass index at diagnosis and breast cancer survival prognosis in clinical trial populations from NRG Oncology/NSABP B-30, B-31, B-34, and B-38
Menée aux Etats-Unis à partir de données portant sur 15 538 patientes atteintes d'un cancer du sein et incluses dans 4 essais cliniques, cette étude évalue l'association entre l'indice de masse corporelle mesuré au moment du diagnostic, les différents traitements, le risque de récidive et la survie des patientes
Background: Body mass index (BMI) has been associated with breast cancer (BC) outcomes. However, few studies used clinical trial settings where treatments and outcomes are consistently evaluated and documented. There are also limited data assessing how patient/disease characteristics and treatment may alter the BMI/BC association. Methods: We evaluated 15,538 BC participants from four NSABP protocols. B-34 studied early-stage BC patients (N=3,311); B-30 and B-38 included node-positive BC patients (N=5,265 and 4,860); B-31 studied node-positive and HER2-positive BC patients (N=2,102). We used Cox proportional hazards regression to calculate adjusted hazards ratios (HRs) for risk of death and recurrence, and conducted separate analyses by ER-status and treatment group. Results: In B-30, increased BMI was significantly related to survival. Compared with BMI<25, HRs were 1.04 for BMI 25-29.9 and 1.18 for BMI≥30 (p=0.02). Separate analyses indicated the significant relationship was only in ER-positive disease (p=0.002) and the sub-group treated with doxorubicin/cyclophosphamide (p=0.005). There were no significant trends across BMI for the other three trials. Similar results were found for recurrence. Increased BMI was significantly related to recurrence in B-30 (p=0.03); and the significant relationship was only in ER-positive BCs (p=0.001). Recurrence was also significant among ER-positive disease in B-38 (p=0.03). Conclusions: In our investigation, we did not find a consistent relationship between BMI at diagnosis and BC recurrence or death. Impact: This work demonstrates that the heterogeneity of BC between different BC populations and the different therapies used to treat them may modify any association that exists between BMI and BC outcome.