Purpose: This study examined the individual and combined effect of having colorectal cancer (CRC) and diabetes mellitus (DM) on health-related quality of life (HRQoL) and sexual functioning.
Methods: Data from questionnaires collected in 2010 among CRC patients and a sample of the general Dutch population were used. All persons older than 60 years were included in this study. DM prevalence among the CRC sample as well as the sample of the general population was self-reported. HRQoL was measured using the European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire version 3.0 (QLQ-C30), and sexual functioning was assessed with four scales from the EORTC-QLQ-CR38.
Results: In total 624 persons without CRC and DM, 78 persons with DM only, 1,731 with CRC only, and 328 with both CRC and DM were included. Having both CRC and DM did not result in lower HRQoL and sexual functioning than the sum of the individual effects of both diseases. CRC, irrespective of having DM, was associated with lower scores on most EORTC-QLQ-C30 subscales, except global health, pain, and appetite loss. CRC was also independently associated with more erection problems among males. DM, irrespective of having CRC, was associated with lower physical functioning and more symptoms of dyspnea.
Conclusions: Having both CRC and DM did not result in lower HRQoL and sexual functioning than the sum of the individual effects of both diseases. As CRC was found to be consistently associated with lower functioning and more symptoms, CRC and its treatment seem to contribute stronger to lower HRQoL and sexual functioning compared with DM.