Does diabetes mellitus as a comorbid condition affect the health-related quality of life in prostate cancer survivors? Results of a population-based observational study.

OBJECTIVE: To assess the health-related quality of life (HRQoL) of long-term, disease-free prostate cancer survivors and compare it with that of prostate cancer survivors with diabetes mellitus (DM), and a Dutch normative population, as comorbidity can have a major impact on HRQoL in cancer survivors. PATIENTS AND METHODS: The Eindhoven Cancer Registry was used to select all men diagnosed with prostate cancer from 1994 to 1998. Questionnaires on HRQoL (Short Form 36) and prostate specific problems (University of California, Los Angeles Expanded Prostate Cancer Index) were sent to 964 patients, and 780 (81%) responded. Excluding patients with disease progression, the sample comprised 525 with prostate cancer and 65 with both prostate cancer and DM. Survivors with DM were more likely to have other comorbid conditions at the time of survey besides DM than were those without DM (74% vs 60%, P = 0.05). At 5-10 years after diagnosis, patients with DM reported worse General Health Perceptions than patients without DM or the normative population (means 52, 61 and 63; P < 0.001). Patients with DM also reported worse Vitality scores (59 vs 63; P < 0.001) than the normative population. Regression analysis indicated that DM was negatively associated with General Health Perceptions (beta = -0.13; P < 0.01) and Vitality (beta = -0.12; P < 0.01). Survivors with DM did not report worse urinary and bowel function or bother, nor more sexual problems than those without DM.
CONCLUSIONS: Except for general health perceptions and vitality, the HRQoL of prostate cancer survivors with or without DM was comparable to a normative population. Survivorship selection can possibly explain, in part, why patients with DM did not report worse generic or disease-specific HRQoL than those without DM, as had been expected.