Colorectal carcinoma: correlation between age, gender and subsite distribution

Several studies have shown a migration in the occurrence of colorectal cancer (CRC) toward a proximal colonic location. The aim of this study was to examine the interrelationship between the anatomical distribution of CRC and gender, age at presentation, and incidence rates for the disease in the inhabitants of Thrace, Northern Greece.

A retrospective study was conducted on CRC cases diagnosed in a northern part of Greece (Evros region, 150.000 inhabitants), in the First Department of Surgery of the University General Hospital of Thrace, between 1982 and 1997. Two time periods were compared (1982-1989 and 1990-1997), at which age at diagnosis (28-88 years), gender, the incidence and subsite location of CRC were identified in the patients. Tumors were classified into right-sided cancers (from the cecum to and including the splenic flexure), left-sided cancers (located in the descending and the sigmoid colon), and rectal cancers (rectal lesions). The chi-square test and Fischer's exact test were used to compare the data.

During the entire study period (1982-1997), 143 cases of CRC were identified in our department. This cohort comprised 71 males and 72 females, with mean ages of 66 years and 64.7 years, respectively. The population remained almost stable during this time period. The incidence of CRC was significantly higher in the latter part of the study (1990-1997 compared to 1982-1989) for both genders (p < 0.001), with this increase being higher among the female patients with CRC (by 17.32%, p = 0.474). The analysis also revealed that the disease occurred at a significantly higher frequency at a later age (p = 0.002), especially in patients with RC (p = 0.001). A proximal migration of CRC was observed in the latter part of the study (p = 0.495), with the frequency of right-sided cancers increasing significantly among the females (by 119%, p = 0.025).

The incidence of CRC has increased in our region. In addition, a proximal migration of tumors over time was identified, especially in older and female individuals, which was linked to a decrease in the incidence of left colon cancer. These findings have important implications for the choice of CRC screening strategies.