Clinicopathological Differences between Right and Left Colorectal Cancer by Sex

Background: Until now, studies on colorectal cancer (CRC) have focused on clinicopathological characteristics based on location without considering sex differences. However, as men and women have fundamentally different physiological characteristics, research results in the clinical field are limited. We aimed to elucidate the differences in the clinicopathological characteristics between right-sided CRC (RCC) and left-sided CRC (LCC) according to sex. Methods: We classified 1492 South Korean patients with no history of colon surgery between July 2005 and June 2015 based on tumor location and sex. For these patients, differences in the clinical characteristics according to sex were compared using univariate and multivariate analyses. Results: Of the 1269 patients, 951 (74.9%) had LCC, and 318 (25.1%) had RCC, making LCC approximately three times more common than RCC. When sex was not taken into account, patients with RCC had significantly higher rates of anemia and undifferentiated cancers than the rates in those with LCC. Even considering sex, anemia and undifferentiated cancer were more prevalent in RCC than in LCC in both men and women. In contrast, age over 65 years and abnormal white blood cell count differed between RCC and LCC only in women. Conclusions: The clinicopathologic characteristics of CRC vary according to the location and sex. Therefore, sex must be considered as a fundamental characteristic of personalized treatment.