Impact of sex, age, and ethnicity/race on the survival of patients with rectal cancer in the United States from 1988 to 2012

Most studies report on colon and rectal cancers collectively, even though biologic and prognostic differences exist between these disease entities. Here, we investigated the effects of sex, age, and ethnicity/race on rectal cancer (RC) mortality by stage focusing on differences before and after 2004. Using the SEER database, we identified 105,511 patients diagnosed with RC from 1988-2012. Main outcomes were disease-specific survival (DSS) and overall survival (OS). In patients with stage I-III RC, women achieved a longer DSS (HR 0.87, P < 0.001) than men, independent of age, from 1988-2012. In stage IV disease, the sex disparity favoring women was limited to the age 18-44 yr cohort (DSS HR 0.79, P < 0.001). The sex difference in DSS (P(interaction) = 0.009) was significantly reduced from 2004 to 2012 across all ages. Hispanics and Native Americans with locoregional RC had inferior DSS relative to Whites from 1988-2003, but these differences were not evident from 2004-2012 (P(interaction) = 0.001). Additionally, Asians with stage I-III RC had superior DSS from 2004 on compared to Whites. Mortality in African American patients improved modestly overall and remained significantly higher than other ethnicities/races across all stages. Sex disparities have narrowed in patients with metastatic RC, but persist in patients with stage I-III disease. These differences are most evident among young patients (18-44 years), where sex disparities have even widened in stage I-III disease. While outcomes have improved for Asians, Hispanics, and Native Americans with stage I-III rectal cancer, black-white disparities remain in all disease stages.