Global trends and projections in colorectal cancer mortality

Abstract

Introduction Colorectal cancer (CRC) is one of most common cause of cancer death worldwide. Mortality rate from CRC has been decreasing in many high-income countries yet in many low and middle-income countries its rate continues to rise. The lack of resources and basic health infrastructure may face many developing countries with important challenges to decrease the CRC mortality rates. Past trends and future predictions of CRC mortality can inform health planners and raise awareness of the need for cancer control action. Methods Numbers of deaths from malignant neoplasms of the colon (ICD-10 C18) and the rectum (C19–21) were obtained from the World Health Organization (WHO) mortality database for the period 1988–2012, by year, sex and age for 49 countries, where high quality data were available for the period of interest. To predict numbers of deaths and mortality rates of colon and rectal cancer up to 2035, we fitted a log-linear age–period–cohort model. We reported both numbers of expected deaths and age-standardized mortality rates per 100,000 person-years for the total population studied as well as country and subsite. Results Mortality rates for colon and rectal cancer are predicted to continue decreasing in most populations studied (32 out of 49 countries), except for most countries in Latin America and the Caribbean. Where rates have decreased in the past, colon cancer mortality rates for these countries combined was 7.2 in 2012 and is expected to be 6.6 per 100,000 person-years in 2035. In countries where rates have increased, the rate was 6.7 in 2012 and will be 7.4 by 2035. In most countries where colon cancer rates have decreased, we also predicted a decline in future rectal cancer mortality (ASR: 3.5 in 2012 and 3.2 in 2035), except, in Ireland, United Kingdom, Australia, Canada and United States, where age-standardized rates are predicted to increase by 2035 (ASR 4.1 vs. 2.9 in 2012). Despite contrasting trends in rates, number of deaths is expected to rise for both colon and rectal cancer in all countries (colon cancer: from 203,690, to 304,440 between 2012 and 2035 (+49.4%), respectively, and rectal cancer: 85,547, and 136,948 in 2012, and 2035, (+60.0%) respectively). Conclusions We highlight further decline in colon and rectal cancer mortality rates in most of countries studied, which however will not compensate the expected rise in number of deaths from this cancer, mainly due to population ageing and growth. Projected reductions of colon and rectal cancer mortality rates in Europe, North America and Oceania are partly related to earlier detection and improved cancer management. The predicted increases in rectal cancer mortality rates in some developed countries are worrisome and warrant further investigations.