SUMMARY: ColoRectal Cancer (CRC) is the third most common cancer diagnosed in both men and women in the United States. The American Cancer Society estimates that approximately 145,600 new cases of CRC will be diagnosed in the United States in 2019 and about 51,020 patients are expected to die of the disease. The lifetime risk of developing CRC is about 1 in 23.

Even though the incidence of Colorectal cancer (CRC) in the United States has been rapidly declining overall, primarily driven by screening, the incidence however has been increasing among adults younger than 50 years of age, according to data in the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program. Based on these findings, the American Cancer Society in 2018 updated its guidelines to include a “qualified recommendation” to begin CRC screening at the age of 45 yrs. The US Preventive Services Task Force (USPSTF) and other major US organizations have however not yet changed their recommendations. The increase in the incidence of CRC in young adults has been attributed to western style, high carbohydrate, high fat, low fiber diet, which can initiate inflammation and proliferation in the colonic mucosa within two weeks. Other lifestyle factors associated with CRC include obesity, high consumption of processed meat and alcohol, low levels of physical activity and cigarette smoking.

The authors in this publication performed a retrospective study examining the National Cancer Data Base (NCDB) registry to determine whether the trends seen through 2013, as published from SEER program had continued to worsen through 2015 (the most recent available data from the NCDB). The National Cancer Data Base is one of the largest cancer registries in the world and includes more than 70% of newly diagnosed cancer cases in the United States and more than 34 million historical records. The researchers also examined available demographic and socioeconomic factors to determine whether they were related to CRC in young adults and further compared clinical characteristics of CRC tumors among age groups, to determine whether younger patients had differences in clinical presentation. A total of 1,185,763 cases were included in the study of whom 130,165 patients were diagnosed at an age younger than 50 yrs and 1,055,598 patients were diagnosed at the age of 50 yrs or older. The proportion of patients diagnosed before the age of 50 yrs was chosen as the Primary endpoint, as most current guidelines recommend screening starting at an age of 50 yrs.

The proportion of the total number of patients diagnosed with CRC under the age of 50 yrs rose from 10% in 2004 to 12.2% in 2015 (P<0.0001). Younger adults presented with more advanced stage of disease (Stage III/IV) than those 50 yrs or older (51.6% versus 40.0% respectively). When racial and ethnic groups were stratified by sex, among men with a diagnosis of CRC before age 50, non‐Hispanic whites showed a proportional increase in diagnosis (P<0.0001), whereas among women, both Hispanic whites (P<0.05) and non‐Hispanic whites (P<0.001) had increases in the proportion of CRC diagnosed before age 50. The rates of CRC diagnosis in young adults increased over time, regardless of income level (P<0.001).The highest proportion of young adult CRC diagnoses occurred in the highest income group. The proportion of CRC cases diagnosed in younger individuals rose in urban areas (P<0.001), but not in rural areas.

It was concluded that based on this study, that the proportion of individuals diagnosed with CRC at an age younger than 50 years, has continued to increase over the past decade in the US. Younger adults also present with more advanced disease and Health Care Providers should be mindful of these data, when screening guidelines are discussed with patients. This study however does not capture oncogenic mutations or tumor laterality, which are known to affect the prognosis. The authors pointed out that the National Cancer Data Base which provided the patient information for this study currently captures laterality only for paired organs. Recent trends in the age at diagnosis of colorectal cancer in the US National Cancer Data Base, 2004‐2015. Virostko J, Capasso A, Yankeelov TE, et al. First published: 22 July 2019. https://doi.org/10.1002/cncr.32347