Increased risk of suicide in New South Wales men with prostate cancer : Analysis of linked population-wide data

Background
An elevated risk of suicide after a diagnosis of prostate cancer has been reported previously in the USA and Sweden. We aimed to identify whether prostate cancer survivors resident in New South Wales Australia are at higher risk of suicide and if so, who is most at risk.

Methods
Data were obtained from the New South Wales (NSW) Cancer Registry for all men diagnosed with prostate cancer in NSW during 1997 to 2007. These were linked by the Centre for Health Record Linkage (CHeReL) to Australian Bureau of Statistics Mortality Data to the end of 2007 to determine vital status and cause of death. We compared the number of suicides observed for prostate cancer survivors with the expected number of suicides based on age- and calendar year- specific rates for the NSW male population using standardised mortality ratios (SMRs). Suicide rate ratios (RR) by disease and patients’ characteristics were estimated using multivariable negative binomial regression to determine the most at risk groups.

Results
During the study period 51,924 NSW men were diagnosed with prostate cancer. Forty nine of these men were subsequently recorded as committing suicide up to 10 years after diagnosis with an SMR of 1.70 (95% CI:1.26–2.25). Twenty six (53%) of these suicides occurred within 12 months after diagnosis. Risk diminished over time since diagnosis (RR in 1–2 years after diagnosis = 0.29, 95% CI: 0.12–0.71, 2–4 years RR = 0.30, 95% CI: 0.14–0.16 and 4+ years RR = 0.26, 95% CI: 0.11–0.60 compared with <1 year since diagnosis). Men with non-localised disease had a higher risk of suicide compared to men with localised disease (RR = 2.68, 95% CI: 1.15–6.23). Men living outside major cities had lower risk of suicide compared to those resident in major cities (rate ratio = 0.42, 95% CI: 0.20–0.87). Single, divorced, widowed or separated men were more likely to commit suicide than married men (RR = 4.18, 95% CI: 2.36–7.42).

Conclusion
Risk of suicide is higher for NSW men diagnosed with prostate cancer than the general age matched male population. Vulnerable or lonely men and those with pre-existing depression or suicidal ideation who are diagnosed with prostate cancer should be offered additional psychological support.