Seasonality of Suicides among Cancer Patients

ABSTRACT

Cancer patients are at increased risk of suicidal behavior. It is well known that suicides show seasonality with peak in the Spring and early Summer suggesting the influence of circa-annual environmental factors. Here we questioned whether cancer diagnosis interacts with the seasonality of suicides. We performed a etrospective analysis of seasonality of suicides among cancer patients registered between 1974 and 2016 in the Surveillance, Epidemiology, and End Results (SEER) database fitting the classical cosinor model . A significant seasonal pattern with a peak in the first half of May was identified. The same peak was observed for both sexes as well as for elderly (> 50 years) and White patients. Patients living in Southern counties had an earlier peak versus those from Northern counties. The rate of both early (within the first year after diagnosis) and late suicides also followed the identical seasonal pattern with peak in May. The analysis per cancer subtypes revealed that only prostate cancer patients had a significant peak in May. Our findings suggest thatcancer diagnosis does not alter the typical seasonal pattern of suicides observed in the general population. Therefore, psychological support in cancer patients must be particularly active in the Spring and early Summer.

KEYWORDS:

• Suicide
• cancer
• season
• cosinor model
• SEER program

Author contributions

Velizar Shivarov proposed research, collected and analyzed data, supervised and coordinated work and wrote the manuscript. Hristo Shivarov analyzed data and wrote the manuscript. Angel Yordanov analyzed data and wrote the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).