Purpose: Suicide risk is reportedly higher for cancer patients than for the general population, but estimates vary and analyses of trends are few. The aim of the present study was to determine whether cancer patients had a higher suicide risk between 1960 and 1999.
Patients and methods: A cohort comprising patients from the Cancer Registry of Norway 1960 to 1997 was linked to suicide diagnosis in the Register of Deaths at Statistics Norway and observed during 1960 to 1999. The cohort consisted of all cancer patients registered in the Cancer Registry of Norway 1960 to 1997 (N = 490,245 patients with 520,823 cancer diagnoses). Suicide was defined according to death certificates based on the International Classification of Diseases (versions 7, 8, 9, and 10).
Results: During the period, 589 cancer patients (407 males and 182 females) committed suicide. The relative risk was elevated for males and females, with standardized mortality ratios (SMRs) of 1.55 (95% CI, 1.41 to 1.71) and 1.35 (95% CI, 1.17 to 1.56), respectively. Risk was highest in the first months after diagnosis. For both sexes, there was a significant decrease in the relative suicide risk over decades. The risk was markedly increased among male patients with cancer of respiratory organs (SMR, 4.08; 95% CI, 2.96 to 5.47). Otherwise, the SMRs varied from 0.76 to 3.67 across cancer types.
Conclusion: Cancer may be a risk factor for suicide, particularly shortly after diagnosis. However, the relative risk gradually decreased during the period 1960 to 1999.