PURPOSE:Age is reported as a risk factor for carcinogenesis, even though age can affect cancer behavior both positively and negatively. Young patients with colorectal cancer reveal different tumor characteristics than average‐age and older‐age groups, although few studies report the influence of age among the entire range of patient ages. The influence of age on clinicopathologic characteristics of sporadic colorectal cancer was analyzed. Whether an age group with distinct tumor characteristics was present was determined.METHODS:A total of 5,436 patients who underwent colectomy in a single institute within a seven‐year period were studied. Data on clinical and histopathologic features of colorectal cancer were collected from the cancer registry and medical records. These characteristics were analyzed according to ten‐year age groups.RESULTS:Eighty‐three patients (1.6 percent) were 30 years of age or younger, whereas 285 (5.5 percent) were 31 to 40 years of age. Most patients (74.6 percent) were 51 to 80 years of age. The proportion of localized tumors (Dukes A and Dukes B) significantly increased as age increased, from 31.3 percent in the 30 years or younger age group to 49 percent in the 80 years or older group (P< 0.001). The proportion of poorly differentiated tumors tended to decreased as age increased (from 16.9 percent in the 30 years or younger group to 6.2 percent in the 80 years or older group;P= 0.009). A similar trend in the proportion of mucin‐producing tumors was also observed (36 percent in the younger groupvs.7.5 percent in the older group;P< 0.001). There was no significantly different distribution of tumor locations among the different age groups.CONCLUSIONS:Age appears to favorably influence the clinicopathological characteristics of sporadic colorectal cancer. As age increased, the characteristics of tumor stage at diagnosis, tumor differentiation, and mucin production improved.