Lung cancer patients have the highest malignancy-associated suicide rate in USA: a population-based analysis

Previous studies have reported that psychological and social distresses associated with a cancer diagnosis have led to an increase in suicides compared to the general population. We sought to explore lung cancer-associated suicide rates in a large national database compared to the general population, and to the three most prevalent non-skin cancers [breast, prostate and colorectal cancer (CRC)].

The Surveillance, Epidemiology and End Results (SEER) database (1973-2013) was retrospectively reviewed to identify cancer-associated suicide deaths in all cancers combined, as well as for each of lung, prostate, breast or CRCs. Suicide incidence and standardised mortality ratio (SMR) were estimated using SEER*Stat-8.3.2 program. Suicidal trends over time and timing from cancer diagnosis to suicide were estimated for each cancer type.

Among 3,640,229 cancer patients, 6,661 committed suicide. The cancer-associated suicide rate was 27.5/100,000 person years (SMR = 1.57). The highest suicide risk was observed in patients with lung cancer (SMR = 4.17) followed by CRC (SMR = 1.41), breast cancer (SMR = 1.40) and prostate cancer (SMR = 1.18).Median time to suicide was 7 months in lung cancer, 56 months in prostate cancer, 52 months in breast cancer and 37 months in CRC (p < 0.001).We noticed a decreasing trend in suicide SMR over time, which is most notable for lung cancer compared to the other three cancers. In lung cancer, suicide SMR was higher in elderly patients (70-75 years; SMR = 12), males (SMR = 8.8), Asians (SMR = 13.7), widowed patients (SMR = 11.6), undifferentiated tumours (SMR = 8.6), small-cell lung cancer (SMR = 11.2) or metastatic disease (SMR = 13.9) and in patients who refused surgery (SMR = 13).

The cancer-associated suicide rate is nearly twice that of the general population of the United States of America. The suicide risk is highest among the patients with lung cancer, particularly elderly, widowed, male patients and patients with unfavourable tumour characteristics. The identification of high-risk patients is of extreme importance to provide proper psychological assessment, support and counselling to reduce these rates.