Abstract 890: Body-mass index, prostate cancer-specific mortality and biochemical recurrence: Meta-analyses of observational and clinical studies
Authors: Cao Yin , Ma Jing 
Published: February 2011

Abstract
Purpose: Obesity, measured by body-mass index (BMI), is unrelated to prostate cancer incidence; however, increasing evidence suggested that obesity was associated with higher prostate cancer-specific mortality, but several large clinical studies showed weak and/or non-significant findings. The impact of obesity on prostate cancer biochemical recurrence is also inconclusive; and it is unknown whether the association is due to late detection or an increased risk of disease progression. We conducted a systematic review and meta-analyses to assess the strength of associations of BMI with prostate cancer-specific mortality and biochemical recurrence.
Methods: We did electronic search on MEDLINE (from January 1, 1980 to September 30, 2009) to indentify observational studies on the association between BMI and prostate cancer-specific mortality, and BMI and prostate cancer biochemical recurrence separately. We used random-effects meta-analysis to determine the risk of prostate cancer-specific mortality and biochemical recurrence associated with a 5 kg/m2 increment in BMI.
Results: We first analyzed ten independent datasets from ten cohort studies to assess the association between BMI and prostate cancer-specific mortality among both healthy population and diagnosed prostate cancer patients. Overall, a 5kg/m2 increment in BMI was significantly associated with 17% (RR 1.17, 95%CI 1.08-1.27, p=0.001) increase in prostate cancer-specific mortality. Among the ten studies, five followed 1,260,509 disease-free individuals in total, and observed 6,787 deaths due to prostate cancer. In this group of healthy population, a 5kg/m2 increase in BMI was associated with 16% (RR 1.16, 95% CI 1.06-1.26, p=0.000) increased risk of prostate cancer death. The other five studies followed survival experience of 16,673 newly diagnosed prostate cancer, and 871 deaths due to prostate cancer were found. Among diagnosed patients, a 5kg/m2 increment in BMI had a 21% non-significantly elevated risk of prostate cancer-specific mortality (RR 1.21, 95% CI 0.97-1.51, p=0.084). Another ten clinical studies of the association between BMI and biochemical recurrence after primary therapy followed a total of 12,147 prostate cancer patients, and identified 2,404 recurrences. A 5kg/m2 increment in BMI was significantly associated with 24% (RR=1.24, 95% CI 1.12-1.37, p=0.000) higher risk of biochemical recurrences among treated prostate cancer patients.
Conclusions: Elevated BMI by 5kg/m2 was significantly associated with 16% higher prostate cancer-specific mortality in healthy population, and 24% increased risk of biochemical recurrence within treated prostate cancer patients. Although the association of BMI with poor survival in prostate cancer patients was within the same magnitude (21%), the lack of statistical significance underscores the need for more investigations.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 890.