J Cancer 2019; 10(22):5388-5396. doi:10.7150/jca.32435 This issue
1. State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
2. Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China
Aims: Racial disparities in cancer mortality persist despite rapid developments in cancer treatment strategies. In recent decades, an increased frequency of patients with young-onset cancer has been reported. However, few studies have assessed racial disparities in clinical features and overall survival among young-onset patients with colorectal, breast, and testicular cancer. Therefore, we evaluated racial disparities in cancer mortality for these three cancer types.
Methods: We extracted the data of eligible patients from the Surveillance, Epidemiology and End Results (SEER) database from 1973 to 2014. Overall and cancer-specific survival rates were compared among races using Kaplan-Meier curves. Adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated, and the association of race with survival was influenced by marital status, surgery and disease stage in Cox proportional hazard models.
Results: We collected the data of 19,574 patients with colorectal cancer, 68,733 with breast cancer, and 26,410 with testicular cancer; all were aged 25-40 years. A higher proportion of Blacks presented with a distant stage at diagnosis compared to Whites and Others (colorectal cancer: 18.0%, 18.5% and 18.4%, respectively, P = 0.004; breast cancer: 3.5%, 6.3% and 4.0%, respectively, P < 0.001; testicular cancer: 6.9%, 10.8% and 8.6%, respectively, P < 0.001). Multivariate analysis showed that Blacks had the highest overall mortality rate (colorectal cancer, HR, 1.277, 95% CI: 1.198, 1.361, P < 0.001; breast cancer, HR, 1.471, 95% CI: 1.420, 1.525, P < 0.001; testicular cancer, HR, 1.887, 95% CI: 1.562, 2.281, P < 0.001). In stratified analyses, Unmarried Blacks had a higher mortality rates (colorectal cancer, HR, 1.318, 95% CI: 1.211, 1.435, P < 0.001; breast cancer, HR, 1.465, 95% CI: 1.394, 1.541, P < 0.001; testicular cancer, HR, 1.944, 95% CI: 1.544, 2.447, P < 0.001). Furthermore, Blacks with colorectal and breast cancer had a higher risk of mortality than Whites at every disease stage, with greatest disparities occurred among individuals at localized stage. The influence of racial disparities on survival was consistent among patients who accepted surgery, but was weak among those who did not undergo surgery for colorectal cancer (Blacks, HR, 1.027, 95% CI: 0.866, 1.219, P = 0.758; Others, HR, 0.919, 95% CI: 0.760, 1.112, P = 0.386) and testicular cancer (Blacks, HR, 1.039, 95% CI: 0.538, 2.007, P = 0.909; Others, HR, 0.772, 95% CI: 0.388, 1.533, P = 0.459).
Conclusions: We demonstrated that Blacks had a worse prognosis for young-onset colorectal, breast, and testicular cancer. Marital status, cancer-directed surgery and disease stage may influence the association of race with the risk of mortality. Equal access to high-quality medical care among races, greater social support and comprehensive interventions are required. Moreover, further studies need to clarify the effects of biological properties like genetic differences between races on cancer patient survival.
Keywords: survival analysis, racial disparities, colorectal cancer, breast cancer, testicular cancer