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Certain lifestyle behaviors may increase the risk of colorectal cancer in males. piola666/Getty Images
  • Colorectal cancer is the third most common cancer worldwide but it is largely preventable, and rates are decreasing in older people.
  • However, colorectal cancer cases in younger people are increasing.
  • A new study has identified seven risk factors that increase the risk of colorectal cancer in younger men.
  • The authors recommend colorectal cancer screening for men under age 45 who are at higher risk.

After breast and lung cancer, colorectal cancer is the third most common cancer worldwide. And only lung cancer causes more deaths. In the United States alone, more than 150,000 people are estimated to be diagnosed with colorectal cancer each year.

Colorectal cancer is most frequently diagnosed in people over the age of 45, with the median age of diagnosis being 66. According to the American Cancer Society, colorectal cancer cases and deaths in older people are decreasing, in part due to widespread screening of those over 50, and the removal of pre-cancerous growths called polyps.

Although the risk of developing colorectal cancer is low for those under the age of 45, the number of cases and deaths in younger people has been increasing since the 1990s.

Now, a study of U.S. veterans has discovered a number of factors that are associated with an increased risk of early-onset colorectal cancer in men. The authors suggest that targeted screening might help prevent some cases.

The study is published in Cancer Prevention Research.

“Although there is a rapid increase in young people being diagnosed with colorectal cancer, the cause is unknown. In young men, colorectal cancer is now the leading cause of cancer-related deaths. Since the majority of CRC is preventable through screening, this study presents information that may be helpful to determine which young men should be screened for colorectal cancer.”

Dr. Anton Bilchik, Ph.D., professor of surgical oncology and division chair of general surgery at Providence Saint John’s Health Center and chief of general surgery and director of the Gastrointestinal and Hepatobiliary Program at Saint John’s Cancer Institute in Santa Monica, California.

From the United States National Veterans Affairs database, the researchers identified 956 men between the ages of 35 and 49 who had been diagnosed with non-hereditary colorectal cancer between 2008 and 2015. Of these, 600 met their criteria for inclusion in the study.

They then matched these with 1,200 controls who had undergone colonoscopy but did not have colorectal cancer, and 1,200 controls who had not undergone colonoscopy.

The researchers looked at sociodemographic and lifestyle factors, family and personal medical history, physical measures, vital signs, medications, and laboratory results for both cases and controls. For variables that could change with the onset of colorectal cancer, data identified from the 6–18 months before diagnosis was used for those with a colorectal cancer diagnosis.

To identify risk factors, they looked at age, cohabitation, employment, body mass index (BMI), cancers in first- or second-degree relative, comorbidities, alcohol use, hyperlipidemia, and use of statins, non-steroidal anti-inflammatory drugs (NSAIDs), or multivitamins.

From this, they identified 15 factors that were independently associated with an increased risk of early-onset colorectal cancer. Of these, they highlighted seven that provided comparable precision, data for which are readily collectable:

  • older age (within the 35- to 49-year-old age range)
  • no regular use of NSAIDs (such as aspirin or ibuprofen)
  • no regular use of statins
  • current alcohol use
  • first- or second-degree relative with colorectal cancer
  • a higher disease burden
  • service-connection/copay variable – a marker for socio-economic status

Some factors increased risk more than others, as corresponding author Dr. Thomas F. Imperiale, research scientist at Regenstrief Institute, told Medical News Today:

“Having a first-degree or second-degree relative with colorectal cancer carried more weight. Two other factors with a greater effect were not taking a statin and not being on a non-steroidal anti-inflammatory drug.”

According to the Centers for Disease Control and Prevention (CDC), several lifestyle factors may increase the risk of colorectal cancer. These include:

Dr. Bilchik, who was not involved in the study, highlighted the role of lifestyle factors:

“This study does suggest that lifestyle plays an important role in the development of colorectal cancer. For example, statin use is associated with high cholesterol, and diet and alcohol has been linked to several other malignancies as well.”

“Interestingly, weight loss, not obesity, was a risk factor, contrary to numerous studies. This is an important finding since unexpected weight loss may be a consequence of colorectal cancer rather than a cause, and therefore warrants further evaluation,” he added.

Simple changes to diet and lifestyle can significantly reduce the risk of colorectal cancer, said Dr. Bilchik.

“A healthy lifestyle including a balanced diet, exercise and the avoidance of processed food and too much red meat and alcohol can reduce the chance of developing colorectal cancer by as much as 80%.”
— Dr. Anton Bilchik

The researchers noted that their study was done only on men, but that the risk of colorectal cancer is twice as high in men as it is in women of any age. However, they are now undertaking similar research into risk factors in women.

They highlighted that not all younger men need screening for colorectal cancer but that those at higher risk might benefit.

“For men 35–44, only those at high risk should be screened. For those men 45–49 years old, guidelines now call for colorectal cancer screening, but do not specify how (i.e., which test).”
— Dr. Thomas F. Imperiale

“The risk factors may be helpful in deciding whether noninvasive testing (with the fecal immunochemical test or with the multi-target stool DNA test) or colonoscopy is more appropriate,” Dr. Imperiale told MNT.

In addition, he hoped that identifying these risk factors might encourage men ages 45–49, who are currently eligible for screening, to come forward for testing.

“The findings are more relevant to male veterans younger than 35–44 now that colorectal cancer screening is recommended beginning at age 45. Nonetheless, the findings also may be useful for convincing 45–49-year-old male veterans that they should be screened,” Dr. Imperiale added.