The number of colorectal cancer cases in people aged 50 and older has fallen. Unfortunately, researchers are reporting that the number of cases among people aged 20-49 has risen. They estimate that this rate is set to increase further over the next 15 years.

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Colorectal cancer, also known as bowel cancer, refers to any cancerous growth, lump or tumor of the colon or rectum.

The decline in colorectal cancer (CRC) cases among older adults has partly been attributed to an increase in colonoscopy screening, recommended for all adults aged 50 and older. Between 1998 and 2006, CRC incidence fell each year by 3% in men and 2.4% in women.

Patients younger than 50, conversely, are not recommended for general screening, and it is in this group that incidence rates are increasing. Not only this, but previous studies indicate that these patients are more likely to present advanced forms of CRC, making treatment of the disease much more difficult and reducing the likelihood of positive outcomes.

CRC is the third most common cancer in the US. In 2013, an estimated 142,820 new cases were reported, along with approximately 50,830 deaths attributed to the disease.

Researchers from the University of Texas MD Anderson Cancer Center in Houston, TX, utilized data from the Surveillance, Epidemiology and End Results (SEER) CRC registry in order to assess the age disparities seemingly present in CRC cases. Specifically, the team obtained data for all patients who had been diagnosed with colon or rectal cancer, from 1975-2010.

They found that the overall rate of CRC incidence had declined by 0.92% between 1975 and 2010 – by 1.03% in men and 0.91% in women. The reduction was most significant in patients aged 75 and above, declining by 1.15%, compared with a decline of 0.97% in patients aged 50-74.

In contrast, CRC incidence rates increased among patients aged 20-49. The increase was 1.99% in patients aged 20-34 and 0.41% in patients aged 35-49.

From their findings, the researchers estimate the following increases in the incidence rates for colon cancer and rectosigmoid and rectal cancer for patients aged 20-34 years:

By 2020:

  • Colon cancer – 37.8%
  • Rectosigmoid and rectal cancers – 49.7%.

By 2030:

  • Colon cancer – 90%
  • Rectosigmoid and rectal cancers – 124.2%.

Conversely, the researchers estimate that by 2030, incidence rates among patients over 50 for colon, rectosigmoid and rectal cancers will fall by around 41%.

“The increasing incidence of CRC among young adults is concerning and highlights the need to investigate potential causes and external influences such as lack of screening and behavioral factors,” write the authors of the study, published in JAMA Surgery.

Along with an absence of screening protocol, certain behavioral factors have been identified as risk factors for the development of CRC; physical inactivity, obesity and poor diet could all be targeted as a way of improving overall health as well as reducing the risk of CRC.

Dr. Kiran K. Turaga, of the Medical College of Wisconsin-Milwaukee, describes the findings of the report as “rather unsettling.” In a related commentary, Dr. Turaga suggests that further research should be conducted to investigate why this increasing incidence may be occurring:

[This] report should stimulate opportunities for development of better risk-prediction tools that might help us identify these individuals early and initiate better screening/prevention strategies. The use of stool DNA, genomic profiling and mathematical modeling might all be tools in the armamentarium of the oncologist in the near future.”

Recently, Medical News Today reported on research revealing that a combination of multiple healthy behaviors can reduce the risk of colorectal cancer.