Socioeconomic position and mortality among patients with prostate cancer: influence of mediating factors

Background

Men with low socioeconomic position experience higher mortality after a prostate cancer diagnosis compared with men with higher socioeconomic position, however, the specific mediators of this association are unclear. We therefore evaluated the influence of potential mediators on the association between socioeconomic position, and prostate cancer specific and all-cause death in prostate cancer patients.

Methods

We conducted a cohort study of prostate cancer patients in the Danish Diet, Cancer and Health study. All patients completed questionnaires and anthropometric measurements at enrollment. Information on vital status, educational level, income, and comorbidity was obtained by linkage to Danish nationwide registries. Clinical data and anthropometric measures were collected from medical records at diagnosis. Cox proportional hazard models were used to compute hazards ratios for all-cause and prostate cancer specific death according to socioeconomic position and potential mediators.

Results

We included 953 prostate cancer patients identified among 27,179 male participants in the Diet, Cancer and Health study who were followed for a median of 6.5 years (interquartile range, 6.4-11.2 years). Patients with low education were more often overweight or obese at baseline. The likelihood of aggressive cancer was almost equally distributed between educational levels. Obesity at baseline, but not at diagnosis, was associated with increased prostate cancer specific and death of all causes. Low socioeconomic position was associated with increased prostate cancer specific and all-cause death. The increased mortality could largely be explained by tumor aggressiveness, comorbidity, treatment, and metabolic indicators, except for patients in the lowest income group.

Conclusions

Our study confirmed the a priori assumption that socioeconomic position is associated with increased mortality after prostate cancer. The increased mortality could largely be explained by lifestyle and clinical parameters.

Clinical trial identification

Legal entity responsible for the study

The study was approved by the regional ethical committees on human studies in Copenhagen and Aarhus (jr.nr.(KF)11–037/01) and by the Danish Data Protection Agency.

Funding

The present study is supported by The Danish Council for Independent Research – Medical Science [Grant No. 271-07-0609], The Scientific Committees of the Danish Cancer Society [Grant No. 225 06 055] and The Health Insurance Foundation [Grant No. 2006B095].

Disclosure

All authors have declared no conflicts of interest.