Abstract
Objective: This study aimed to investigate the potential value of circumferential resection margin (CRM) in colon cancer prognostics.Summary Background Data: CRM has been extensively studied as an important prognostic factor in rectal and esophageal cancer, but not in colon cancer.Methods: Data from 6,681 CRM-positive patients and 25,908 CRM-negative patients diagnosed with colon cancer in 2010–2015 were obtained from the Surveillance, Epidemiology, and End Results database. Statistical analysis methods utilized included the chi-square test, Kaplan-Meier estimates, Cox proportional, and X-tile software analyses.Results: After propensity score matching, CRM positivity was found to be negatively related with survival (P < 0.001). X-tile software identified 0 and 30 mm as optimal cutoff values (P < 0.001) for prognosis, which was applicable only in stage II–IV patients. A 20 and 33% risk decrease were observed in patients with CRM between 0 and 30 mm [95% confidence interval (CI) = 0.76–0.84], and larger than 30 mm (95% CI = 0.62–0.71), respectively. Chemotherapy strongly benefited prognosis with a hazard ratio of 0.36 (95% CI = 0.34–0.38) for overall survival (OS). Patients with a CRM value of 0–30 mm seemed to benefit most from chemotherapy compared with other groups. CRM and number of regional lymph nodes are independent risk factors, and the latter is a good substitute for CRM in AJCC stage I patients.Conclusion: CRM positivity is a strong unfavorable survival indicator for colon cancer patients. A better outcome is expected with CRM values larger than 30 mm. This cutoff value only applied to stage II–IV patients. For stage I patients, number of regional lymph nodes is a good substitute to predict survival. Chemotherapy was another favorable prognostic factor, especially for patients with a CRM value between 0 and 30 mm.
Highlights
Colorectal cancer is the third most prevalent carcinoma in both males and females in the United States, and is mainly treated by surgery, chemotherapy, as well as radiation [1]
To further assess the impact of circumferential resection margin (CRM) status on survival, a bipartite propensity score matching analysis was performed with stratification for age, American Joint Committee on Cancer (AJCC) stages [16], administration of chemotherapy, number of regional lymph nodes examined and positive regional lymph nodes
Significant differences were only observed for year of diagnosis, T and N stages, administration of radiation, and number of positive regional lymph nodes, minimizing the possible bias from different baseline characteristics when analyzing the effect of CRM on survival (Table 1 after matching)
Summary
Colorectal cancer is the third most prevalent carcinoma in both males and females in the United States, and is mainly treated by surgery, chemotherapy, as well as radiation [1]. As the main treatment for colorectal cancer, surgery is expected to minimize local recurrence and prolong disease-free survival. It is critical to ensure no tumor invasion at the edge of the specimen. The circumferential resection margin (CRM), is a term used to describe the relationship between the resection margin and the tumor. According to the 8th Edition of the American Joint Committee on Cancer (AJCC) Cancer Staging Manual, the CRM refers to the distance in millimeters between the deepest point of tumor invasion in the primary cancer and the margin of resection in the retroperitoneum or mesentery [2]. CRM involvement ( called CRM positivity) should be defined as presence of remnant tumor cells after resection [3]
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