Abstract
Background: Current guidelines recommend discussion of adjuvant chemotherapy (AC) for stage II colon cancer (CC) with high-risk features despite lacking conclusive randomized trial data. We examined AC administration in this population and its effect on overall survival (OS) for available patient, tumor, and treatment characteristicsMethods: Using National Cancer Data Base, a cohort of 42,971 stage II CC patients diagnosed from 2004 to 2009, who underwent surgery with curative intent, was identified. Chi-square test and multivariate logistic regression were used to analyze baseline characteristics and to calculate odds of chemotherapy administration, respectively. Survival analysis was conducted using Kaplan Meier survival analysis with log-rank test and Cox proportional hazards regression modeling.Results: AC was administered to 26% patients. The use decreased with advancing age and elderly patients received more single-agent than multi-agent chemotherapy (3 vs. 2.4%, p < 0.0001). Major predictors of AC use included pT4 status, evaluation of <12 lymph nodes, high grade tumors, positive resection margins, age <65 years, left sided tumors, and low comorbidity score. AC was associated with improved OS regardless of high-risk features (pT4, undifferentiated histology, <12 lymph node evaluation, or positive resection margins), tumor location, age, gender, comorbidity index, chemotherapy regimen or type of colectomy (adjusted HR: single-agent 0.55, multi-agent 0.6; p < 0.0001). In subgroup analysis, AC use compensated for the survival differences otherwise seen between left and right sided tumors in the non-chemotherapy population.Conclusion: AC in stage II CC was associated with improved OS regardless of age, chemotherapy type or high-risk features. It improved 5-years OS irrespective of tumor location and seemed to compensate for the survival difference seen between right and left sided tumors noted in the non-chemotherapy group.
Highlights
Colorectal cancer is the third leading cause of cancer diagnosis in the United States (U.S.), both among men and women [1, 2]
We identified 42,971 patients from National Cancer Data Base (NCDB) who were diagnosed with stage II colon cancer between 2004 and 2009
The current study was undertaken to provide a better assessment of the overall survival (OS) benefit of adjuvant chemotherapy in stage II colon cancer with regard to various high-risk features including pT4, inadequate lymph node evaluation, high grade tumors and those with positive surgical margins, along with the other important prognostic factor of tumor sidedness [32, 33]
Summary
Colorectal cancer is the third leading cause of cancer diagnosis in the United States (U.S.), both among men and women [1, 2]. Since there are few definitive prospective clinical trials which have evaluated the use of adjuvant chemotherapy in stage II colon cancer, current clinical practice guidelines by the American Society of Clinical Oncology (ASCO) and the National Comprehensive Cancer Network (NCCN) recommend discussing chemotherapy in patients with tumors possessing high-risk features or microsatellite stability (MSS) and all T4 tumors [17,18,19,20]. Population-based studies have failed to demonstrate substantial OS benefit with the use of adjuvant chemotherapy for all patients with poor-prognostic or high-risk features [22, 23]. Current guidelines recommend discussion of adjuvant chemotherapy (AC) for stage II colon cancer (CC) with high-risk features despite lacking conclusive randomized trial data. We examined AC administration in this population and its effect on overall survival (OS) for available patient, tumor, and treatment characteristics
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