Background

The use of chemotherapy among patients with stage II colon cancer is controversial. We aimed to define the utilization and factors associated with the receipt of chemotherapy and the impact of chemotherapy on long-term prognosis among a large, multiinstitutional cohort of patients.

Materials and methods

We identified 876 patients who underwent resection for stage II colon cancer between 2004 and 2013 at one of seven participating institutions. Overall survival (OS) and recurrence-free survival (RFS) time was calculated from the date of the index procedure to the date of death.

Results

A total of 163 patients (18.6%) received adjuvant chemotherapy and this utilization decreased over time (P = 0.003). Younger age (P < 0.001), margin positivity (odds ratio [OR], 12.16; 95% confidence interval [CI]: 2.57-57.52; P = 0.002), and the presence of perineural invasion (OR, 1.24; 95% CI: 1.07-1.44; P = 0.005) increased the likelihood of receiving chemotherapy. Receipt of chemotherapy was associated with improved median OS and RFS. After controlling for all factors, the addition of oxaliplatin to 5-fluorouracil did not affect survival, and there was no difference in OS (hazard ratio [HR], 0.74; 95% CI: 0.27-2.06; P = 0.57) or RFS (HR, 0.71; 95% CI: 0.32-1.58; P = 0.88) with adjuvant treatment, including for patients with high-risk features (OS-HR, 0.63; 95% CI: 0.33-1.19; P = 0.15; RFS-HR, 0.77; 95% CI: 0.32-1.86; P = 0.56).

Conclusions

The utilization of chemotherapy has declined over time after resection for stage II colon cancer. Chemotherapy was not independently associated with improved OS or RFS in this study group, including in patients with high-risk features. Future prospective studies should strive to identify the subset of stage II colon cancer patients that will benefit the most from the addition of adjuvant chemotherapy.

Background

Prior studies attempting to identify disparities in the care of patients with appendiceal (AC) or colorectal cancer (CRC) with peritoneal metastasis (PM) are limited to single-institution, highly selected patient populations. This observational cohort study sought to identify factors associated with specialty care for Medicare beneficiaries with AC/CRC-PM.

Materials and methods

Patients >65 years old in the United States diagnosed with AC/CRC and isolated PM were identified within the Medicare Standard Analytic File (2013-2017). Mixed-effects analyses assessed patient factors associated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) and outpatient consultation with a peritoneal surface malignancy (PSM) surgeon, and Cox proportional-hazards analysis compared 3-year overall survival (OS) between patients receiving CRS/HIPEC versus systemic therapy alone.

Results

Among 7,653 patients, only 250 (3.3%) underwent CRS/HIPEC. Among those individuals who did not undergo CRS/HIPEC (N=7,403), only 475 (6.4%) had outpatient consultation with a PSM surgeon. Patient factors independently associated with lower odds of CRS/HIPEC and PSM surgery consultation included older age, greater comorbidity burden, higher social vulnerability index, and further distance from a PSM center (p<0.05). CRS/HIPEC was independently associated with better 3-year OS compared with systemic therapy alone (HR=0.29, 95%CI=0.21-0.38).

Conclusion

An exceedingly small proportion of Medicare beneficiaries with AC/CRC-PM undergo CRS/HIPEC or even have an outpatient consultation with a PSM surgeon. Significant disparities in treatment and access to care exist for patients with higher levels of social vulnerability and those that live further away from a PSM center. Future research and interventions should focus on improving access to care for these at-risk patient populations.