Background <p>Research on mortality outcomes and non-cancer-related causes of death in patients with malignant brain tumors remains limited. This study aims to identify the prevalence of non-cancer-related causes of death after brain cancer (BC) diagnosis.</p> Methods <p>Data of patients diagnosed with BC in the USA between 2000 and 2019 from the Surveillance, Epidemiology, and End Results (SEER) database were retrieved and analyzed. Standardized mortality ratios (SMRs) were calculated for all the reported causes of death.</p> Results <p>A total of 59,663 deaths were reported during the follow-up period. The highest number of fatalities (34,677) occurred within the first year following BC diagnosis. BC-attributable deaths were the leading cause of mortality (55,482; 93%), followed by non-cancer deaths (3888; 6.5%). BC patients had an increased risk of non-cancer attributable&#xa0;deaths (SMR = 6.12; 95% CI 5.93–6.31) including heart diseases (<i>N</i> = 938; SMR = 5.3; 95% CI 4.96–5.65), cerebrovascular diseases (<i>N</i> = 453; SMR = 13.17; 95% CI 11.98–14.44), accidents and adverse effects (<i>N</i> = 227; SMR = 2.97; 95% CI 2.6–3.39), and septicemia (<i>N</i> = 155; SMR = 13.39; 95% CI 11.36–15.67).</p> Conclusion <p>Compared to the general population, BC patients had a statistically significant higher risk of death from most of the reported causes.</p>