Prostate cancer diagnosis linked to suicide, cardiac death

Key Points

Boston-Receiving a diagnosis of prostate cancer is accompanied by significantly increased risks of suicide and cardiovascular death, according to recent results of a U.S. population-based cohort study.

The study-a collaborative effort among researchers from Harvard Medical School, Boston; the Karolinska Institutet, Stockholm, Sweden; and the University of Iceland, Reykjavík#8212;found that suicide risk is particularly high immediately after a prostate cancer diagnosis is made.

The investigation included 342,497 American men listed with a prostate cancer diagnosis in nine Surveillance, Epidemiology, and End Results (SEER) registries between 1979 and 2004. Information on death by suicide or cardiovascular cause was determined through linkage with the National Death Index.

The results showed that during the first year after their diagnosis, men with prostate cancer had a statistically significant 40% excess risk of death by suicide and a statistically significant 9% excess risk of death by cardiovascular disease.

Further analyses exploring risks according to time period after diagnosis showed that the risk of death by suicide was greatest immediately after diagnosis, being almost doubled in the first 3 months, but remained significantly elevated during the rest of the year. The risk of cardiovascular death was also highest immediately after diagnosis, being doubled during the first month, and remained significantly increased during months 2 to 6, but was actually decreased during the last 6 months of follow-up.

"We believe that we have documented the 'tip of the iceberg' of the immense psychological suffering of being diagnosed with prostate cancer," said co-author Unnur A. Valdimarsdóttir,, PhD, associate professor and head of the Centre of Public Health Sciences at the University of Iceland.

"In fact, because the reference group was not a cancer-free population, our results probably underestimate the relative risks of mortality due to cardiovascular events and suicide after prostate cancer diagnosis.

"Practicing urologists need to be aware of this issue, and recognizing that the risk of adverse outcomes is concentrated during the first few weeks following diagnosis, we believe interventions should be targeted to this sensitive period. However, there is a need for further research to explore whether refined methods of conveying the diagnostic message as well as increased emphasis on emotional support will reduce stress and the risk of these adverse outcomes among newly diagnosed patients," she told Urology Times.

The results of the SEER-based analyses are consistent with the findings from another recently published, prospective cohort study conducted by Dr. Valdimarsdóttir, and colleagues investigating a Swedish population of men diagnosed with prostate cancer between 1961 and 2004 (PLoS Med 2009; 6:e1000197). The latter study showed increased risks for suicide and cardiovascular events (fatal and nonfatal) among men who were newly diagnosed with prostate cancer, especially during the first few weeks after the diagnosis.

"In light of the rising diagnostic activity and consequently increased number of men diagnosed with prostate cancer in many countries, we have been motivated to explore whether the diagnosis itself could possibly impose severe, stress-induced health consequences for these men," Dr. Valdimarsdóttir, noted.

Risk higher among single men

The statistical analyses for the SEER-based study explored the association between prostate cancer diagnosis and CVD mortality and suicides within strata of age, race, marital status, calendar period, education, income, and tumor stage (disease severity). The results showed that the risks of cardiovascular mortality and suicide were strongly modified by marital status and calendar time; ie, the relative risk was higher for men without a partner and in earlier calendar periods (pre-PSA 1979-'86 and peri-PSA 1987-'92 eras).

"The lack of an increased risk of suicide in the PSA era may reflect the higher proportion of indolent cancers being diagnosed, which is reasonably less stressful, while increased public awareness of the disease in recent years as well as refined practice and support to patients around the diagnosis may also play a role," Dr. Valdimarsdóttir observed.

A lack of access to data on physical and psychological comorbidities introduces a possibility of selection bias; ie, rates of prostate cancer diagnosis may be higher among men with cardiovascular disease or suffering psychiatric symptoms since they are already receiving medical care. However, such bias appears unlikely since the greatest risks were observed when diagnostic activity for prostate cancer was relatively lower (in the pre-PSA era), noted Dr. Valdimarsdóttir.

"We were able to control for comorbidities in our Swedish population study, and this issue did not affect our main findings," she added.

Results from the U.S. population study were published online in the Journal of the National Cancer Institute (Feb. 2, 2010).