Examining Colon Cancer Outcomes in a Universal Health Care System Reveals High Survival Benefit

When comparing survival among patients with colon cancer in the United States Department of Defense’s Automated Central Tumor Registry (ACTUR) with those in the Surveillance, Epidemiology, and End Results (SEER) program, investigators found that better survival outcomes were noted in a universal health care system compared with the general population, according to the results of a study published in Cancer Epidemiology, Biomarkers & Prevention.¹

After a median follow up of 56 months and 49 months for the ACTUR and SEER groups, respectively, ACTUR cases appeared to yield significantly improved overall survival vs SEER cases (log rank P <.0001). After further adjusting for age, region at diagnosis, tumor characteristics, and surgery, investigators reported the ACTUR cases had an 18% lower mortality risk than SEER cases (HR, 0.82; 95% CI, 0.79-0.87). Lower mortality rates were observed across almost all subgroups that were stratified by age, gender, race (with the exception of Asian/Pacific Islanders), and year of diagnosis. The improved mortality was especially evident in Black vs White patients across all models.

“In this study, we observed significant better survival among ACTUR patients with colon cancer than among those in the SEER population. In addition, the ACTUR cases were more likely than SEER cases to have an earlier stage at diagnosis. To the best of our knowledge, this study is the first one comparing survival of patients with colon cancer between [the US military health system (MHS)] and SEER,” the authors of the study wrote.

Data from the study came from both the Department of Defense’s ACTUR, as well as the National Cancer Institute’s SEER program. Patients included in the study had colon adenocarcinoma that had been histologically diagnosed from January 1, 1987, to December 31, 2013, and had been entered into either the ACTUR or SEER databases. Patients were aged 18 years or older at diagnosis.

A total of 11,907 cases of colon cancer were identified from ACTUR and matched with 23,814 cases from SEER. In the ARTUR dataset, patients were most likely to present with stage I disease vs SEER (22.67% vs 18.64%) and were less likely to present with stage IV disease (18.74% vs 21.63%). Additionally, the ACTUR group was more likely to have grade 1 tumors (15.36% vs 9.71%) and less likely to have grade 3 (14.54% vs 18.41%) or grade 4 (0.29% vs 0.95%) tumors compared with the SEER group. Moreover, the ACTUR group had more tumors of unknown location (8.43%) than the SEER group (2.16%). The percentage of patients who did not receive surgery was lower in the ACTUR arm (5.45%) than the SEER arm (7.24%). However, both groups had similarly high rates of patients who underwent surgery (ACTUR, 92.9%; SEER, 92.4%).

Additional data from the study compared insurance types between the 2 groups and indicated that relative to those in the ACTUR database, the adjusted hazard ratios in the SEER group were 0.94 for those with insurance (95% CI, 0.79-1.12), 0.98 for insurance with no specifics (95% CI, 0.75-1.27), 1.31 for Medicaid of any kind (95% CI, 1.05-1.63), 1.73 for uninsured (95% CI, 1.3102.29), and 1.12 for unknown insurance status (95% CI, 0.65-1.95).

When comparing for tumor stage at diagnosis, ACTUR cases were less commonly diagnosed at a later stage (prevalence ratio, 0.90; 95% CI, 0.85-0.94). The association was found to be particularly significant in patients who were 50 to 64 or 65 to 74 years old, in Black and White patients, and in men, although the association had borderline significance in women, as well.

“MHS beneficiaries with colon cancer had better survival than their counterparts in the general population. The tendency of more survival benefit among Blacks than Whites may suggest the potential impact of universal health care on the reduction of racial disparity in survival among [patients with] colon cancer. Future studies are warranted to identify factors contributing to the improved survival,” the investigators concluded.

Reference

Lin J, McGlynn KA, Shriver CD, et al. Comparison of survival among colon cancer [atients in the U.S. Military Health System and patients in the Surveillance, Epidemiology, and End Results (SEER) Program. Cancer Epidemiol Biomarkers Prev. Published online June 23, 2021. doi:10.1158/1055-9965.EPI-20-1267