A Strong Case for Earlier Colorectal Cancer Screening and Detection

Colorectal cancer is widely known as a malignancy that affects older individuals, but that doesn’t mean that the young are immune or invincible against it.

In the US at least, incidence of colorectal cancer in younger individuals below 50 has grown over the last two decades, while the mortality rate has increased by 1.3% annually from 2008 to 2017. On the other hand, death rates have dropped for those who are much older; mortality has decreased by 3% per year for individuals aged above 65 and by 0.6% for those aged between 50 and 64 years.

Referred to as early onset colorectal cancer (EOCRC) that affects those aged below 50, the more aggressive malignancy is a result of a few suspect causes. While risk factors such as hereditary or familial history of colorectal cancer are well-documented causes of EOCRC, others may offer justification for even earlier cancer screening for the lower-than-average risk age groups.

Metastatic cancer, that is, cancer that has spread away from the primary organ to other distant organs, is typically viewed as an advanced-stage cancer. However, new evidence suggests that the spread of cancer from the colon to the abdominal cavity or other organs like the lungs and liver may occur much sooner, even as soon as the primary tumor has developed.

By combining genomic analysis with computer simulation, a team at the Stanford University of Medicine found that “some tumor cells are capable of metastasizing from the get-go”.

The implications of these findings are heavy, particularly since slow-growing colorectal cancer tumors often do not present symptoms until several years later. Especially for younger individuals who are not regularly screened, colorectal cancer could potentially metastasize and grow asymptomatically even before these individuals are eligible for screening.

Other findings from the team’s genomic analysis also showed that specific combinations of gene mutations were more commonly found in patients with metastatic cancer. These genetic changes could potentially become important biomarkers in determining the risk of metastasis, and eventually directing treatments.

Most individuals below their 50s will not be screened for colorectal cancer due to the perceived lower-than-average risk for that age group. This in turn delays detection of any precancerous lesions and cancer diagnosis.

Amongst other factors exacerbating the mortality rate further is the higher incidence of left-side colorectal cancer in these younger individuals. Left-side or distal colon cancer is typically more unstable genetically as a result of chromosomal instability, which in turn makes it a more aggressively growing cancer. That having been said, left-side cancer polyps are morphologically polypoid and more conspicuous, and therefore more easily detected than right-side colorectal cancer upon a colonoscopy.

Concurrently, environmental and lifestyle factors, in particular chronic and widespread ones like diabetes and obesity also increase the likelihood of EOCRC. Obesity as a result of a high-fat diet and individuals with more abdominal fat is a well-established cause of higher colorectal cancer risk. However, this risk increases further in younger individuals, as chronic obesity is often accompanied with other lifestyle characteristics such as a lack of physical activity and poor eating habits.

Even more concerning is how rapidly the population of obese individuals is growing.

As of 2018, over 50 percent of young adults aged above 20 are considered either obese or severely obese, and this trend shows no sign of abating.

The lack of screening for these individuals below their 50s puts them at risk of colorectal cancer developing and growing undetected. Any delays in detection and diagnosis further impact the available treatment options and with it, the likelihood of success.

While the new findings that suggest early metastasis may impact the treatments that are applicable, colorectal cancer remains a curable cancer as long as it is detected and diagnosed early.