Índice de masa corporal como factor pronóstico del cáncer de próstata

Abstract

This Doctoral Thesis is devoted to the study of obesity, a potentially modifiable factor, as a prognostic factor for prostate cancer outcomes, which has showed inconsistent results in the scientific literature to date. We used different methodological strategies aiming at analyzing the role of obesity in prostate cancer prognosis, to respond to the following points: 1) to detect the presence of recommendations regarding obesity and healthy lifestyles in clinical practice guidelines available for prostate cancer through a systematic review, 2) to analyze if body mass index (BMI) and obesity, measured as BMI 30 kg/m2, were associated with prostate cancer mortality through a systematic review and meta-analysis, 3) to analyze if BMI and obesity, measured as BMI 30 kg/m2, were associated with the development of biochemical recurrence after a radical prostatectomy through a systematic review and meta-analysis, and 4) to estimate the association of obesity with both outcomes (mortality and biochemical recurrence) and with other prognostic outcomes (metastases and castration resistance) from the cohort of prostate cancer cases provided by the MultiCase-Control Study (MCC-Spain), a study conducted on Spanish population, through the application of survival analysis techniques. To obtain the proper results, different analytical strategies were used (e.g., metaanalytic techniques using random-effect models, Kaplan-Meier estimations, multivariate Cox regression models, etc.), depending on the objectives and the approach selected. After that, several facts can be concluded. First, recommendations on weight loss and healthy lifestyle in prostate cancer’s clinical practice guidelines of Societies and Governments were very infrequently covered. Second, high heterogeneity was found among the studies that analyzed the association between obesity and prostate cancer prognosis. The sources of heterogeneity were diverse, including the wide range of BMI sources of measurement and different definitions of overweight and obesity, different outcome definitions and different quality and design of the individual studies. Nevertheless, the heterogeneity was considerably reduced in subgroup analyses performed according to these characteristics. Third, obesity (BMI 30) was associated with prostate cancer specific mortality and all-cause mortality compared with patients with normal weight (BMI < 25). Also, obesity was associated with higher risk of biochemical recurrence after receiving a radical prostatectomy. The knowledge generated by this Thesis may contribute to the application of different interventions to reach and maintain a healthy weight for improving prostate cancer outcomes.