Background: National Comprehensive Cancer Network treatment guidelines for patients with locally advanced rectal cancer include neoadjuvant chemoradiation followed by total mesorectal excision and adjuvant chemotherapy. The objective of the current study was to examine the rate of adjuvant chemotherapy and associated survival in patients with stage II/III rectal cancer.
Methods: The 2006 to 2011 National Cancer Data Base was queried for patients with AJCC clinical stage II/III rectal cancer who underwent neoadjuvant chemoradiation and surgical resection. A mixed effects multivariable logistic regression identified factors associated with the receipt of adjuvant chemotherapy. A mixed effects Cox proportional hazards model was used to estimate the adjusted effect of receiving adjuvant therapy on 5-year overall survival (OS).
Results: A total of 14,742 patients were included; 68% of the cohort did not receive adjuvant chemotherapy. When controlled for clinical stage of disease, patients who were aged >70 years, had a higher comorbidity score, and had a pathologic complete response had lower odds of receiving adjuvant therapy. There was a 22-fold difference in the risk-adjusted rate of adjuvant therapy use among hospitals (3.1%-67.7%). Adjuvant therapy was associated with increased 5-year OS when controlled for patient factors, stage of disease, and pathologic response (hazard ratio, 0.65; 95% confidence interval, 0.59-0.71). The greatest survival benefit was noted among patients who achieved a pathologic complete response (hazard ratio, 0.40; 95% confidence interval, 0.23-0.67).
Conclusions: There is poor compliance to National Comprehensive Cancer Network guidelines for adjuvant chemotherapy in patients with locally advanced rectal cancer after neoadjuvant chemoradiation and surgery. Adjuvant therapy appears to be independently associated with improved OS regardless of stage of disease, pathologic response, and patient factors. The greatest survival benefit was observed in patients who were complete responders. Age and comorbidities were found to be significantly associated with nonreceipt of adjuvant therapy. Improved rehabilitation and physical conditioning may improve the odds of patients receiving adjuvant therapy. Cancer 2017;52-61. © 2016 American Cancer Society.
Keywords: adjuvant chemotherapy; outcomes; practice guidelines; rectal cancer.
© 2016 American Cancer Society.