Men with a body mass index (BMI) of 30 and higher were less likely to be diagnosed with prostate but more likely to die from it than men of normal weight, according to a study published in the Journal of the National Cancer Institute.
Previous studies have linked obesity to an increased risk of different types of cancer. However, it is not yet clear whether obesity directly increases the risk of prostate cancer or whether it does so indirectly by affecting the efficacy of prostate cancer screening.
For this study, Dr. Laureb Hurwitz and her colleagues at the National Cancer Institute studied the relationship between body mass index (BMI) and prostate cancer screening outcomes, incidence, and mortality in 36 756 men who participated in the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial from 1993 to 2001.
The participants in this study were required to undergo annual PSA testing for five years and digital rectal examination (DRE) for three years after baseline. A positive test was defined as a PSA screening exceeding 4 ng/mL or a DRE indicating certain distinctive variables like prostate nodularity, induration, asymmetry, or loss of anatomic landmarks.
The researchers observed that at baseline, men with obesity (BMI of 30 or higher) were significantly less likely to screen positive for either the PSA test or DRE. In addition, men who are obese were more likely not to go for PSA or DRE screening as recommended due to reasons such as refusal, discomfort, equipment problems, or clinician difficulty palpating the gland.
Furthermore, the researchers found that compared with men of normal weight, the odds of an inadequate test increase by 17-fold for men with a BMI of 35-39 kg/m2 and 25-fold for men with a BMI of 40 kg/m2 and higher.
The researchers also noted that all men with a positive screen underwent a biopsy regardless of BMI. According to the researchers, every 5 kg/m2 increase in BMI was associated with 6% decreased odds of stage I-II prostate cancer, and 9% decreased odds of stage III-IV prostate cancer. However, there was a 21% increased odds of prostate cancer mortality.
In addition, the study findings revealed that BMI was not associated with high-grade or aggressive prostate cancer (defined as stage IV or Gleason score 8 or higher disease).
“Combined, these results suggest that delayed diagnosis of prostate cancer may not be driving the greater risk of prostate cancer mortality among screened individuals with obesity,” Dr Hurwitz’s team wrote. “Instead, the risk may be due to effects of obesity on promoting disease progression and/or differential treatment uptake or efficacy among individuals with obesity.”
Source: Renal and Urology News
Journal source: JNCI