| ObjectiveAge and tumor location are two important factors underlying the heterogeneity of colon cancer, however site-dependent differences were only explored in late-onset colon cancer patients by far. The aim of this study was to investigate the clinicopathologic characteristics of early-onset colon cancer (aged 40 years and younger) and to explore the difference between left-sided and right-sided colon cancer by sex, age, family history, tumor location, histological type, staging, metastasis and survival, which we hope to make contributions to the future research of site-dependent gene expression signature and accomplishment of personalized targeted therapy in early-onset colon cancer patients.MethodsData from 149 cases of early-onset colon cancer aged 40 years and younger were collectedin Qilu Hospital of Shandong University from January 2004 to November 2014, including gender, age, family history of colon cancer, tumor location, histological type, staging and survival. All of patients were divided into two groups. Those with tumors located in the ileocecal junction, ascending colon, hepatic flexure of colon, transverse colon were classified as right-sided colon cancer (75 cases), the others with tumors located in splenic flexure of colon, descending colon, sigmoid colon were classified as left -sided colon cancer (74 cases).χ2 test was used for ratio comparison and kaplan-meier log-rank analysis was for survival difference.Results1. Similar incidence proportion of left-sided colon cancer could be seen as compared to right-sided colon cancer in early-onset patients, which was 49.66% and 50.34% respectively. The tumor was most often located in sigmoid colon and least in transverse colon.2. Early-onset colon cancer was more often in males. The male to female ratio in left-sided and right sided colon cancers was similar which was 1.64 and 1.88 respectively (P>0.05).3. The proportion of patients aged 35 years and younger in the left-sided colon cancer was 63.51%(47/74), which was higher than the right-sided colon cancer group (44.00%,33/75). The difference was statistically significant (P=0.017).4. There was no significant difference in the family history, T stage, M stage, and the mucous cell carcinoma between the right-sided and left-sided colon cancer patients (P>0.05).5. More patients of the left-sided early-onset colon cancer patients were in advanced stage. The proportion of stage Ⅲ-Ⅳ and lymphnode metastasis in the left and right-sided colon cancer groups were 57.05% vs 48%(P=0.044) and 63.51% vs.43.67%(P=0.011) respectively.6. The right-sided colon cancer in early-onset patients had better prognosis than the left-sided group, the median overall survival time was not-reached vs 77.57m (P= 0.013). However, only T stage(HR=2.91, p=0.013) and M stage (HR=4.92, p<0.001) were prognostic for OS in the Cox regression analysis despite that HR of right-sided colon cancer was 0.61 (p=0.176). In stage IV early-onset colon cancer patients, right-sided colon cancer had a trend of good prognosis compared with left-sided cases (HR=0.43, p=0.083).ConclusionTumor location is a strong predictor of clinico-pathological characteristics and prognosis in early-onset colon cancer patients. Left-sided colon cancer patients were younger, with earlier lymph node metastasis, more advanced stage and worse overall survival compared to right-sided colon cancer. |
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