Purpose <p>This study aimed to identify the treatment-related factors associated with suicide in patients with cancer within the first two years following diagnosis.</p> Methods <p>We analyzed data from a hospital clinical database and national cause-of-death statistics to identify patients with cancer admitted to Kaohsiung Veterans General Hospital between January 2011 and December 2020 who died by suicide. Demographic characteristics and medical treatment information were collected. Patients with cancer who died by suicide (suicide group) were matched in a 1:4 ratio with those who did not die by suicide (non-suicide group) according to sex, age at diagnosis, year of diagnosis, cancer type, and cancer stage. Treatment-related factors were compared between the two groups using univariate and multivariate logistic regression analyses.</p> Results <p>Among 32,479 patients with cancer, 78 died by suicide. Of these, 59 met the inclusion criteria and were included in the final analysis, alongside 236 matched patients who did not die by suicide. Univariate analyses revealed that the suicide group had higher rates of benzodiazepine and/or hypnotic use, antidepressant use, and psychiatric consultations. In multivariate analyses, benzodiazepine and/or hypnotic use and psychiatric consultation remained significantly associated with suicide, whereas antidepressant use did not.</p> Conclusion <p>Patients with cancer who died by suicide were more likely to have received benzodiazepines and/or hypnotics and psychiatric consultations within two years of diagnosis. These associations likely reflect greater underlying psychiatric distress and unmet mental health needs rather than treatment-related harm.</p>