Greater visceral and thigh subcutaneous fat are associated with higher risks of advanced and fatal prostate cancer (PCa), according to a new prospective study.

In addition, visceral fat is associated with a higher risk of these outcomes among men with a lower body mass index (BMI). Investigators found no association between any adiposity measure and total or high-grade PCa.

A team led by Barbra A. Dickerman, PhD, of the Harvard T.H. Chan School of Public Health in Boston, said that to their knowledge, their study is the first prospective investigation of directly measured fat distribution and the risk of advanced PCa. Dr Dickerman and her colleagues studied 1832 Icelandic men in the Age, Gene/Environment Susceptibility-Reykjavik Study. All men underwent baseline computed tomography imaging of fat deposition, bioelectric impedance analysis, and measurement of BMI and waist circumference. Through linkage with nationwide cancer registries, the investigators identified 172, 43, 41, and 31 new cases of total, high-grade, advanced, and fatal PCa, respectively, during follow-up. The median follow-up time was 10.1 years until PCa diagnosis and 10.4 years until PCa death.

Among all men, each 1 standard deviation (SD) increase in visceral fat (85.7 cm2) and thigh subcutaneous fat (39.2 cm2) was associated with a 31% and 37% higher risk of advanced and fatal PCa, respectively, Dr Dickerman’s team reported in Cancer.

The associations between visceral fat and aggressive and fatal PCa were stronger among men with a BMI less than 27 kg/m2 and were statistically significant only among these men. In this group, each 1-SD increase in visceral fat was associated with a 2-fold higher risk of advanced and fatal PCa in a fully adjusted model.

In addition, Dr Dickerman and her collaborators found that each 5 kg/m2 increase in BMI was associated with 52% and 56% greater risks of advanced and fatal PCa, respectively. Obese men (BMI 30 kg/m2 or higher) had 2.5- and 2.6-fold higher risks of advanced and fatal disease, respectively. Each 1-SD (10.3 cm) increase in waist circumference was associated with 40% and 45% higher risks of advanced and fatal PCa, respectively.

“The identification of the adiposity phenotypes at highest risk of clinically relevant prostate cancer may help to elucidate the mechanisms linking obesity with aggressive disease and target intervention strategies,” the investigators concluded.

In an accompanying editorial, Celina H. Shirazipour, PhD, and Stephen J. Freedland, MD, of Cedars-Sinai Medical Center in Los Angeles, commented that the new findings, in addition to existing evidence related to obesity and PCa, “highlight the need to examine lifestyle interventions that target fat loss in promoting optimal prostate cancer outcomes.”

Based on the new findings and the existing body of knowledge on diet and exercise, “new opportunities arise for knowledge development and practice for researchers and clinicians.”

Investigators might benefit from including measures that assess visceral fat as outcomes in interventions, and clinicians would benefit from collecting knowledge of fat location in addition to total weight, Drs Shirazipour and Freedland wrote. “This information, alongside existing outcome measures such as inflammatory markers, may be beneficial in indicating whether prostate cancer risks are being targeted during treatment.”

References

Dickerman BA, Torfadottir JE, Valdimarsdottir UA, et al. Body fat distribution on computed tomography imaging and prostate cancer risk and mortality in the AGES-Reykjavik Study. Cancer. 2019; published online ahead of print. doi:10.1002/cncr.32167

Shirazipour CH, Freedland SJ. Obesity, visceral adiposity,  and prostate cancer: What is the role of lifestyle interventions? Cancer. 2019; published online ahead of print.

http://doi.wiley.com/10.1002/cncr.32165