Obesity and the outcome of young breast cancer patients in the UK: the POSH study
Menée au Royaume-Uni auprès de 2 956 patientes âgées de moins de 40 ans lors d'un diagnostic de cancer du sein, cette étude prospective évalue l'association entre l'obésité et la survie des patientes
Background : Obese breast cancer patients have a poorer prognosis than non-obese patients. We examined data from a large prospective cohort study to explore the associations of obesity with tumour pathology, treatment and outcome in young British breast cancer patients receiving modern oncological treatments. Patients and Methods : 2956 patients aged ≤40 at breast cancer diagnosis were recruited from 126 UK hospitals from 2001-2007. Height and weight were measured at registration. Tumour pathology and treatment details were collected. Follow-up data were collected at 6, 12 months, and annually. Results : 2843 eligible patients (96.2%) had a body mass index (BMI) recorded: 1526 (53.7%) were under/ healthy-weight (U/H, BMI <25 kg/m2), 784 (27.6%) were overweight (ov, BMI ≥25 to <30) and 533 (18.7%) were obese (ob, BMI ≥30). Median tumour size was significantly higher in obese and overweight patients than U/H patients (Ob 26 mm vs. U/H 20 mm, p<0.001; Ov 24 mm vs U/H 20 mm, p<0.001). Obese and overweight patients had significantly more grade 3 tumours (63.9% vs. 59.0%, p=0.048; Ov 63.6% vs U/H 59.0% p=0.034) and node positive tumours (Ob 54.6% vs. U/H 49.0%, p=0.027; Ov 54.2% vs. U/H 49%, p=0.019) than U/H patients. Obese patients had more ER/PR/HER2 negative tumours than healthy-weight patients (25.0% vs18.3%, p=0.001).Eight-year overall survival (OS) and distant disease free interval (DDFI) were significantly lower in obese patients than healthy-weight patients (OS: Hazard Ratio 1.65, p<0.001; DDFI: Hazard Ratio 1.44, p<0.001). Multivariable analyses adjusting for tumour grade, size, nodal and HER2 status indicated that obesity was a significant independent predictor of OS and DDFI in patients with ER positive disease. Conclusions : Young obese breast cancer patients present with adverse tumour characteristics. Despite adjustment for this, obesity still independently predicts DDFI and OS.