Eric Miller

PhD, MSPH

NCI

Epidemiologist

PLCO (Learn more about this study)

PLCO-246

Dec 12, 2016

Diabetes, PSA levels and prostate cancer screening outcomes

Numerous studies have shown a reduced risk of prostate cancer among men with diabetes. Further, studies have demonstrated that the reduction can likely be attributed to lower rates of low grade tumors. It has been suggested that the lower rates of low grade tumors are not due to lower risk but rather lower PSA levels compared to men without diabetes. Although there does not appear to be a higher rate of high grade tumors among men with diabetes compared to those without, if more low grade tumors are missed among men with diabetes, a higher proportion of diagnosed cancers should be high grade (and more aggressive) compared men without diabetes. Consistent with this, studies of prostate biopsies have found a higher percentage of high grade tumors at biopsy among men with diabetes compared to those without. Since a major drawback of prostate cancer screening has been overdiagnosis of tumors that may never progress, it is possible that screening might be more effective in men with diabetes if it identifies more aggressive tumors at an earlier stage while reducing the number of low grade tumors that may not progress. If true, diabetes could be an added consideration when determining when to recommend prostate cancer screening to patients. While previous studies have examined the relationship between diabetes and prostate cancer, tumor grade, or PSA levels, we are unaware of any that have assessed the impact of screening on these relationships. In addition, while levels of PSA have been compared by diabetes status among men with or without prostate cancer separately, few studies are able to examine the levels over time in men who develop prostate cancer. Using the PLCO Screening Trial Prostate Dataset and Free PSA Dataset, this analysis will assess PSA levels, free PSA, and screening outcomes among men with diabetes compared to those without.