A recent study published in the journalCancer Epidemiology, Biomarkers & Prevention suggests that the burden of distant or advanced stage colorectal cancer increased in younger individuals from 2000 to 2016.
The study involving individuals aged 20–55 years also found a negative link between age and the likelihood of presenting with distant stage early onset colorectal cancer (EOCRC). In other words, younger individuals were at the greatest risk of distant stageTrusted Source colorectal cancer.
The researchers reported an increase in the proportion of individuals with distant stage colorectal cancer among all racial and ethnic groups in the study, but the trend was more pronounced in younger non-Hispanic Black and Hispanic individuals.
Dr. Neil Murphy, a scientist at the International Agency for Research on Cancer, part of the World Health Organization, said: “These and other recent data really highlight the urgent need for further research identifying risk factors for early onset colorectal cancer. Despite a growing number of studies in this area, risk factors for colorectal cancer in young adults remain largely unknown.”
“The study also reinforces the importance of those eligible for colorectal cancer screening from age 45 to get screened on time and for younger adults not to ignore any red flag symptoms — e.g., blood in the stool, abdominal pain, unintentional weight loss, plus others — and consult a physician. The earlier a cancer is diagnosed, the better the clinical outcome,” Dr. Murphy added.
Evaluating changes in colorectal cancer incidence
Previous studiesTrusted Source have shown an increase in the average annual percent changeTrusted Source for distant stage EOCRC, defined as colorectal cancer in individuals below the age of 50 years.
One of the objectives of the present study was to understand the changes in the contribution of distant stage disease to the overall number of EOCRC cases between 2000 and 2016. Evaluating this along with changes in the incidence rate can help estimate the burden of advanced stage colorectal cancer.
Another objective of the present study was to evaluate the changes in the incidence rates of colorectal adenocarcinomasTrusted Source, a specific subtype of colorectal cancer that accounts for the majority of colorectal cancers.
Significantly, in previous studies, researchers have pooled the rates of subtypes of colorectal cancers together, which the authors of this study claim can bias the estimated incidence of the different colorectal cancer stages.
Adenocarcinomas have been the focus of guidelines for screening and diagnosing colorectal cancers. Thus, it is important to independently assess the incidence rates of colorectal adenocarcinomas to better shape public health policies.
Increase in incidence rates
The researchers compared the 3-year average annual incidence rates of colorectal adenocarcinoma during 2000–2002 with those from 2014–2016. Among the different stages of colorectal adenocarcinomas, they observed the greatest increase in distant stage cancer during this period.
Comparing 2000–2002 with 2014–2016, the researchers found a 133% increase in distant stage rectal-only adenocarcinomas in individuals aged between 20–29 years. However, this increase in the percentage of cancer incidence accompanied only a small increase in the absolute incidence rate. The incidence rate of rectal-only distant stage adenocarcinomas in 20–29-year-olds increased from 0.06 to 0.14 cases for every 100,000 individuals.
Similarly, distant stage rectal-only and colon-only colorectal cancers rose by 97% and 49%, respectively, in individuals aged 30–39 years.
The researchers also found an increase in regional adenocarcinomas, especially at the rectal site. For instance, the incidence rate of regional rectal-only adenocarcinoma increased by 45% and 43% in individuals aged 30–39 years and 40–49 years, respectively.
Contribution of distant stage disease
The researchers found an increase in the proportion of distant stage colorectal adenocarcinomas in all age groups from 2000–2002 to 2014–2016. This was associated with a decrease in the proportion of in situ and localized adenocarcinomas in all age groups.
The study noted the largest increase of distant stage adenocarcinomas at the rectal subsite. These increased from 18% to 31% in individuals aged 20–29 years and from 20% to 29% in the 30–39 years age group from 2000–2002 to 2014–2016.
The researchers found a negative correlation between age and the likelihood of presenting with distant or regional stage colorectal cancer. Individuals aged 20–29 years had a 29% chance of presenting with distant stage disease, compared with 20% in individuals aged 50–55 years.
Distant stage colorectal cancer and race
During the study period, there was an increase in the proportion of distant stage cases for people of all racial and ethnic subgroups. However, the largest increase was in young non-Hispanic Black and Hispanic individuals.
Among non-Hispanic Black individuals aged between 20–29 years, there was a steep increase in the proportion of distant stage colon-only cancer, which rose from 20% to 34%, and rectal-only cancer, which rose from 0% to 46%.
Similarly, the proportion of distant stage rectal-only cancers increased from 28% to 41% in Hispanic individuals aged 20–29 years. Although the proportion of distant stage colorectal adenocarcinomas increased in younger Hispanic and non-Hispanic Black individuals, the actual number of cases in these subgroups was lower than those observed in older individuals.