Changes in colorectal cancer incidence by site and age from 1973 to 2015: a SEER database analysis

Abstract

Previous studies have reported incidence and mortality declines for colorectal cancer (CRC). We evaluated recent temporal trends of colorectal cancer in the United States for the last 4 decades. Using the Surveillance, Epidemiology, and End Results (SEER) database, we identified primary CRCs diagnosed between 1973 and 2015. Temporal changes were evaluated by 6-year time periods. Age-adjusted incidence rates and annual percentage change (APC) for CRC were calculated by site and gender. Age-standardized relative survival rates were also evaluated. We identified 878,632 CRC patients, 51% of whom were men. For both genders, the proportions of new diagnoses of right-sided colon cancer (RCC) remained relatively stable, with the APC of - 0.8 and - 0.6 for the male and the female, respectively. There was a relative increase in RCC for the younger aged group (< 49 years). In contrast, the proportions of left-sided colon cancer (LCC) and rectosigmoid-cancer (RSC) decreased significantly over time. For those aged 0-49, the age adjusted incidence rates showed a small increase (in both genders), whereas age-adjusted incidence rates declined for those aged 50-64 and > 65 (in both genders). Our study showed near significance in the decline of CRC mortality rates in this population, except the 1-year age-standardized survival of LCC and RSC, and the 5-year age-standardized RCC in females. There was a significant increase in RCC for the younger aged group (< 49 years). In contrast, the proportions of LCC and RSC decreased significantly over time.

Keywords: Age-standardized survival; Colorectal cancer; SEER database; Tumor location shift.