Abstract
BackgroundTumor sidedness as a prognostic factor in advanced stage colon cancer (CC) is well established. The impact of tumor sidedness on the clinical outcomes of stage II and III CC has not been well studied.MethodsThe National Cancer Database (NCDB) was utilized to identify patients with pathological stage II and III primary adenocarcinoma of the colon from 2010 to 2015 using ICD-O-3 morphology and topography codes: 8140-47, 8210-11, 8220-21, 8260-63, 8480-81, 8490 and C18.0, 18.2,18.3, 18.5,18.6, 18.7. Univariate (UVA) and multivariable (MVA) survival analyses and Kaplan–Meier Curves with Log-rank test were utilized to compare overall survival (OS) based on tumor location and treatment received.ResultsA total of 35,071 patients with stage II (n = 17,629) and III (n = 17,442) CC were identified. 51.3% female; 81.5% Caucasian; median age 66 (range, 18–90). Majority of stage II and III tumors were right sided, 61.2% (n = 10,794) and 56.0% (n = 9,763). Microsatellite instability high (MSI-H) was more common in stage II compared to III, 23.3% (n = 4,115) vs 18.2% (n = 3,171) (p < 0.0001). In stage II MSI-H CC right was more common than left, 78.3% (n = 3223) vs 21.7% (n = 892). There was no significant difference in survival between stage II MSI-H left vs right (5-year OS 76.2 vs 74.7%, p = 0.1578). Stage II MSS CC right was more common than left, 56.0% (n = 7571) vs 44.0% (n = 5943), and survival was better in the left vs right (5-year OS 73.2 vs 70.8%, p = 0.0029). Stage III MSI-H CC was more common in the right than in the left, 75.6% (n = 2,397) vs 24.4% (n = 774) and survival was better in the left (5-year OS 62.5 vs 56.5%, p = 0.0026). Stage III MSS CC was more common in the right than in the left, 51.6% (n = 7,366) vs 48.4% (n = 6,905), and survival was better in the left vs right (5-year OS 67.0 vs 54.4%, p < 0.001).ConclusionSurvival was better in left sided tumors compared to right in stage II MSS, stage III MSS, and stage III MSI-H CC.
Highlights
Colorectal cancer is the third most common cancer and third leading cause of cancer related mortality in the United States (US) [1]
Given the paramount importance of Microsatellite Instability (MSI) status in locoregional CC management and the propensity for microsatellite instability-high (MSI-H) tumors for the right side, it is imperative to analyze the impact of tumor sidedness with known MSI status
The aim of this study is to evaluate the impact of primary tumor side, left-sided (L) versus right-sided (R), on clinical outcomes based on known MSI status in patients with stage II and III CCs
Summary
Colorectal cancer is the third most common cancer and third leading cause of cancer related mortality in the United States (US) [1]. It is estimated that 104,610 new cases of colon cancer (CC) will be diagnosed in the US in 2020. Two thirds of patients present with locoregional disease, and primary tumor location could have a significant impact on the prognosis in CC across all stages [1,2,3]. The predictive role of tumor sidedness was described in the locoregional [4,5,6] and metastatic setting [7, 8]. Embryologic and physiologic differences exist between the left and right sides of the colon. Tumor sidedness as a prognostic factor in advanced stage colon cancer (CC) is well established. The impact of tumor sidedness on the clinical outcomes of stage II and III CC has not been well studied
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