Body fat distribution on computed tomography imaging and prostate cancer risk and mortality in the AGES‐Reykjavik study

Abstract

Background The World Cancer Research Fund classifies as “strong evidence” the link between obesity and the risk of advanced prostate cancer. In light of the different hormonal profiles associated with where adipose is stored, this study investigated the role of objectively measured body fat distribution and the risk of clinically relevant prostate cancer. Methods This was a prospective study of 1832 men in the Age, Gene/Environment Susceptibility–Reykjavik study. From 2002 to 2006, participants underwent baseline computed tomography imaging of fat deposition, bioelectric impedance analysis, and measurement of body mass index (BMI) and waist circumference. Men were followed through linkage with nationwide cancer registries for the incidence of total (n = 172), high‐grade (Gleason grade ≥8; n = 43), advanced (≥cT3b/N1/M1 at diagnosis or fatal prostate cancer over follow‐up; n = 41), and fatal prostate cancer (n = 31) through 2015. Cox regression was used to evaluate the association between adiposity measures and prostate cancer outcomes. Results Among all men, visceral fat (hazard ratio [HR], 1.31 per 1–standard deviation [SD] increase; 95% confidence interval [CI], 1.00‐1.72) and thigh subcutaneous fat (HR, 1.37 per 1‐SD increase; 95% CI, 1.00‐1.88) were associated with risk of advanced and fatal disease, respectively. Among men who were leaner based on BMI, visceral fat was associated with both advanced and fatal disease. BMI and waist circumference were associated with a higher risk of advanced and fatal disease. No adiposity measures were associated with total or high‐grade disease. Conclusions Specific fat depots as well as BMI and waist circumference were associated with the risk of aggressive prostate cancer, which may help to elucidate underlying mechanisms and target intervention strategies.

Abdominal and pelvic adipose tissue distribution and risk of prostate cancer recurrence after radiation therapy

“…This study prospectively evaluated adipose tissue distribution using CT scans and found that BMI and WC were associated with increased risk of both advanced and fatal disease. Visceral adiposity was associated with a higher risk of advanced prostate cancer, while higher amounts of thigh subcutaneous fat was associated with increased risk of fatal prostate cancer 11 . Our results, along with these mixed findings from other studies, suggest that more research incorporating accurate measures of adipose tissue distribution is needed to better understand the link between obesity and prostate cancer outcomes.…”

“…Visceral fat area (VFA), subcutaneous fat area (SFA), and PPAT area were measured using radiotherapy planning computed tomography (CT) scans, as previously described 9 . Briefly, VFA and SFA were calculated using a single CT slice at the level of the L4/L5 vertebrae, a validated method used by other groups 11‐13 . PPAT area was calculated using a single CT slice at the first anterior point of the pubic symphysis, as we and others have done previously 9,14,15 .…”

Obesity, visceral adiposity, and prostate cancer: What is the role of lifestyle interventions?

“…The findings from Dickerman et al's research, in addition to existing evidence on obesity and prostate cancer, highlight the need to examine lifestyle interventions that target fat loss in promoting optimal prostate cancer outcomes. Two lifestyle behaviors frequently examined within weight‐loss research are diet and exercise.…”

“…In light of the findings by Dickerman et al and the existing body of knowledge on diet and exercise, new opportunities arise for knowledge development and practice for researchers and clinicians. First, researchers could benefit from including measures that assess visceral fat as outcomes in interventions, whereas clinicians would benefit from collecting knowledge of fat location in addition to the total weight.…”

“…Second, the research provides support for the importance of the timing of lifestyle interventions. According to the information provided by Dickerman et al on the cohort in the AGES‐Reykjavik study, optimal benefits may be experienced prior to diagnosis through early preventative interventions. Within the AGES‐Reykjavik study, the men who demonstrated higher visceral fat also had lower self‐reported physical activity during youth and midlife.…”