Associations of pre-diagnostic body mass index with overall and cancer-specific mortality in a large Austrian cohort
Menée en Autriche auprès de 8 673 patients atteints de cancer (durée médiane de suivi : 11, 9 ans), cette étude de cohorte évalue l'association entre une obésité avant le diagnostic et la mortalité spécifique et globale
Purpose : Although obesity is a well-known risk factor for several cancers, its role on cancer survival is poorly understood. Methods : Within the VHM&PP cohort, 8,673 cancer patients (42.2 % women) were followed over a median time of 11.9 years. Cox proportional hazard models were used to estimate the association of pre-diagnostic overweight (BMI 25.0–29.9 kg/m2) and obesity (BMI ≥ 30.0 kg/m2) with all-cause and cancer-specific mortality. Cubic restricted splines were additionally modeled. Results : During 71,126 person-years, 4,571 deaths were observed. Compared to normal weight, overweight was associated with statistically significantly decreased all-cause mortality (HR 0.93; 95 % CI 0.87–0.997) and cancer-specific mortality (HR 0.91; 95 % CI 0.84–0.99). Underweight was statistically significantly associated with 28 % increased overall mortality, in particular in men [HR 2.02 (95 % CI 1.43–2.83) vs. HR 0.96 (95 % CI 0.71–1.30) in women]. J-shaped associations were found between BMI and mortality with the nadir around a BMI of 25 kg/m2. Analysis by cancer site showed though not statistically significantly that overweight was associated with reduced mortality, while obesity was associated with increased cancer-specific mortality except cancers of the upper digestive tract. In patients with local stage colorectal cancers, obesity was associated with increased all-cause (vs. normal weight HR 1.90; 95 % CI 1.03–3.52) and cancer-specific mortality (HR 3.17; 95 % CI 1.29–7.81). Conclusion : Overweight patients have a better overall prognosis, while for obesity no association and for underweight worse prognosis were found. Our results on common cancers indicate that there are tumor- and stage-specific differences.