Risk of aggressive prostate cancer may be raised by diabetes

Milan, Italy-Prostate cancer patients who also have long-term diabetes mellitus and/or diabetes with organ failure may have a higher likelihood of developing more aggressive, poorly differentiated prostate cancer, a new study suggests.

“The relationship between diabetes mellitus and prostate cancer is controversial. Some evidence suggests that type II diabetes mellitus patients have an estimated 14% reduction in the risk of prostate cancer. Our database analysis revealed that prostate cancer patients with long-term DM and/or DM with organ failure are all at a higher risk of harboring a poorly differentiated tumor,” first author Alessandro Nini, MD, of the Urological Research Institute, University Vita-Salute San Raffaele, Milan, Italy, reported during a presentation at the European Association of Urology annual congress in Milan.

“This should be considered when advising diabetic patients about prostate cancer screening and management.”

Dr. Nini obtained data from 104,822 prostate cancer patients in the Surveillance, Epidemiology, and End Results (SEER) Medicare database. The patients had received different treatment modalities and were diagnosed between 1992 and 2005. Dr. Nini employed logistic regression analyses to test the relationship between the patients’ diabetes status and two endpoints: poorly differentiated tumors (Gleason score 8-10) and locally advanced prostate cancer (T3-T4 disease).

He observed that 14% of the overall study population was diabetic. The mean duration of diabetes in the database patients was 41.6 months (median, 35 months). Forty-two percent of diabetic patients had uncomplicated diabetes, while 21% had diabetes with complications, and 37% had diabetes with organ failure. After adjusting for all other covariates, diabetic patients were 5% more likely to harbor poorly differentiated prostate cancer. Demographically, more diabetic patients were African-American than Caucasian, more single than married, older, with lower annual incomes, and less educated (college education) compared to non-diabetic patients, Dr. Nini pointed out.

Diabetes raises risk of high-grade tumor

Diabetes was seen to increase the risk of high-grade tumor in univariable and multivariable analyses for the prediction of high-grade tumor, and emerged as a predictive factor for locally advanced tumor in univariable analysis. At sub-analysis, patients with long-term diabetes in excess of 35 months and diabetes with organ failure were respectively 15% and 21% more likely to harbor poorly differentiated prostate cancer relative to their non-diabetic counterparts (p<.03). Conversely, short-term diabetes, diabetes without complications, and diabetes with complications were not independent predictors of poorly differentiated prostate cancer (odds ratio [OR]: 1.02-1.04, all p≥.2). Similarly, diabetes itself was not an independent predictor of locally advanced disease (OR: 0.94, p=.1), Dr. Nini noted.

Alexander Govorov, MD, of Moscow State Medical University, Moscow, who co-chaired the poster session at which the study was presented, commented that when a physician has a diabetic patient with organ failure, common practice is to offer him a less aggressive treatment, keeping in mind his diabetes. He said he was not certain how one would find a balance in treatment based on Dr. Nini’s conclusions.

“First of all, we should take into consideration that PSA in diabetic patients is lower than in normal patients,” Dr. Nini explained. “When we have a patient with organ failure, we have to identify other comorbidities such as heart attacks, vascular disease, and so on. It could be that prostate cancer will not even be the main cause of death for the patient or have an impact on the prognosis of the patient. I would advise to first consider the other implications of the diabetes, and then consider prostate cancer.”UT