colorectal cancer CRC epidemiology is being transformed by the birth cohort effect, also known as birth cohort CRC, an observed phenomenon of increased risk of colorectal cancer across generations for people born after 1960, according to a new narrative review.
Birth cohort CRC is associated with increased rectal cancer ( colon cancer) diagnosis and distant-stage (higher than local-stage) colorectal cancer diagnosis, and the incidence of early-onset colorectal cancer (EOCRC), defined as occurring before age 50 years, is increasing.
Recognizing this birth cohort effect may improve our understanding of the risk factors, etiology, and mechanisms of colorectal cancer, as well as the public health implications of increased incidence.
“Changes in epidemiology mean we need to redouble our efforts to optimize early detection and prevention of colorectal cancer,” said the review’s lead author, a professor of gastroenterology at the University of California, San Diego. said Professor Sameer Gupta, MD. Medscape Medical News. Mr. Gupta is co-director of the Cancer Control Program at UC San Diego’s Moores Cancer Center.
This includes “paying attention to potential warning signs and symptoms of colorectal cancer. iron deficiency anemia “Rectal bleeding is otherwise unexplained, including in people under 45,” he said.
“We also need to ensure that all people over the age of 45 who are eligible for screening have every opportunity to be screened for colorectal cancer,” Gupta added.
The review is Published online in Clinical gastroenterology and hepatology.
Track birth cohort trends
Colorectal cancer rates are increasing in the United States for people born since the early 1960s, the authors write.
An increase in EOCRC was observed among Generation X (born between 1965 and 1980), and the proportion subsequently increased after age 50 in this generation. The ratio is 1.22 times for those born between 1965 and 1969, and 1.58 times for those born in 1975. There are more people born in 1979 than people born between 1950 and 1954.
This proportion is now increasing among younger generations as a whole, especially among Millennials (those born between 1981 and 1996) as they enter middle adulthood. The incidence rate is 1.89 times higher for those born between 1980 and 1984 and 2.98 times higher for those born between 1990 and 1994 than among those born between 1950 and 1954.
These birth cohort effects are evident worldwide, despite differences in population age structures, screening programs, and diagnostic strategies around the world. As this trend continues, the authors write, doctors expect that colorectal cancer incidence will likely continue to increase as high-risk birth cohorts age.
In particular, they noted four important changes in colorectal cancer incidence. First, the incidence increases steadily until he is 50 years old and levels off after 60 years. Currently, rectal cancer is predominant until he is 50-59 years old. The rate of distant-stage disease increases most rapidly between ages 30 and 49 and decreases more slowly between ages 60 and 79, compared with the rate of local-phase disease. Additionally, increasing rates of EOCRC have been observed in all racial and ethnic groups since the early 1990s.
These changes have led to a significant shift in the types of patients diagnosed with colorectal cancer today compared to 30 years ago, including those under 60 years of age, as well as those who are black, Asian or Pacific Islander, and American.・Higher proportion of Indian/Alaska Native and Hispanic patients.
The combination of age-related increases in colorectal cancer and birth cohort-related trends means that more people will be diagnosed with colorectal cancer in the coming years, especially as Generation X patients move into their 50s and 60s. The numbers are likely to increase significantly, the authors write.
Research and clinical impact
Birth cohort CRC, including increased incidence of EOCRC, is likely caused by a variety of influences, including demographic, lifestyle, early childhood, environmental, genetic, somatic factors, and their interaction, the authors conclude. pointed out. Examples of these broad categories include male gender, food insecurity, income inequality, diabetes, alcohol useunhealthy dietary patterns, in utero exposure to certain drugs, microbiome concerns such as childhood antibiotic exposure and dysbiosis.
“From a research perspective, this means we need to think about risk factors and mechanisms associated with birth cohort, not just age at diagnosis,” said Dr. Gupta. “To date, most studies of epidemiological changes have not taken into account birth cohorts, such as post-Generation X or pre-baby boomers.”
Although additional research is needed, the change in epidemiology has some immediate clinical implications, Gupta said. If you’re under 45, it’s important to raise awareness about the signs and symptoms of colorectal cancer, such as blood in your stool, iron deficiency anemia, unintentional weight loss, and your family history.
For those aged 45 years and older, the primary focus should be on increasing screening participation and follow-up after abnormal results, addressing disparities in screening participation, and optimizing screening quality.
Additionally, as the incidence of colorectal cancer continues to increase, health systems and policy makers must ensure that all patients have access to guideline-aligned care and innovative clinical trials, the authors say. writing. This access may be particularly important to address the increasing burden of rectal cancer, as treatments rapidly evolve to more effective treatments, such as neoadjuvant chemotherapy and radiotherapy. He added that treatments with less morbidity are on the horizon.
“Interesting concept”
“Birth cohort colorectal cancer is an interesting concept that allows us to consider colorectal cancer risk according to birth cohort in addition to age,” said Shuji Ogino, MD, director of the Molecular Pathology and Epidemiology Program at Brigham and Women’s Hospital in Boston. It is stated as follows.Massachusetts has spoken Medscape Medical News.
Ogino was not involved in this study, but is a member of the Cancer Immunology and Cancer Epidemiology Program at Dana-Farber Harvard Cancer Center. In the EOCRC study, he and his colleagues found different biogeographic and pathogenic trends across age groups.
“Further research is needed to elucidate the complex pathogenesis of birth cohort colorectal cancer and early-onset colorectal cancer,” Professor Ogino said. “Tumor cells and tissues have specific past and ongoing pathological signatures that can be detected to better understand birth cohort colorectal cancer and early-onset colorectal cancer.”
This research was funded by several National Institutes of Health/National Cancer Institute grants. Mr. Gupta disclosed consulting for Geneoscopy, Guardant Health, Universal Diagnostics, InterVenn Bio, and CellMax. Another author reported consulting to Freenome, Exact Sciences, Medtronic, and Geneoscopy. Ogino does not report any relevant financial disclosures.
Carolyn Crist is a health and medical journalist reporting on the latest research for Medscape Medical News, MDedge, and WebMD.