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News: Obesity Among Reasons Why Colorectal Cancer is on the Rise for Gen Xers and Millennials

News: Obesity Among Reasons Why Colorectal Cancer is on the Rise for Gen Xers and Millennials

Diet, weight and activity can influence your risk of developing the disease before age 50.

You might think of colorectal cancer as a condition that only affects older people. While it’s true that the risk shoots up the older you get, an increasing number of younger people are developing the disease.

“People can get colon cancer under 50,” says Rya Kaplan, MD, a gastroenterologist with Trident Medical Center in Charleston, South Carolina. “It’s not the norm, but it can happen.” That's part of the reason the American Cancer Society (ACS) updated its screening guidelines in May 2018. It now recommends beginning at age 45, rather than age 50.

Colorectal cancer is the third most common cancer among US men and women, and of cancers that affect both men and women, this type is the second leading cause of death. However, about 90 percent of people live five or more years if their colorectal cancer is found early.

Evidence for younger screening
According to a February 2017 study in the Journal of the National Cancer Institute, while colorectal cancer has declined in people over the age of 55 since the 1970s and 80s, it has jumped for people younger than 55. “We are certainly seeing younger patients [with colorectal cancer] more frequently,” says Keith Roach, MD, Sharecare’s chief medical officer.

For people aged 20 to 39 years, colon cancer rates increased by 1 to 2.4 percent every year since the mid-80s. In 40- to 54-year-olds, colon cancer rates increased from 0.5 to 1.3 percent since the mid-90s.

Rectal cancer rates have also increased:

  • 3.2 percent annually for people aged 20 to 29 between 1974 and 2013
  • 3.2 percent for 30- to 39-year-olds since the 80s
  • 2.3 percent for the 40 to 54 age groups since the 90s

Another study, published in the journal Cancer in March 2016, found that of more than 258,000 people with colorectal cancer, about one in seven developed colorectal cancer before age 50.

Too much red meat and too little fiber might increase a person's risk of colorectal cancer, as can insufficient exercise and excess body weight. In fact, an October 2018 study published in JAMA Oncology suggests obesity and weight gain in young adulthood can increase the risk of early onset colorectal cancer in women under 50.

Researchers tracked more than 85,000 women between 25 and 42 years old for a period of 22 years, during which time 114 women under 50 developed the disease. Compared to women of a "normal" weight—a body mass index (BMI) between 18.5 and 22.9, according to the study—those in the obesity range (a BMI above 30) had a 93 percent higher risk for colorectal cancer. Weight gain beginning at age 18 was also associated with a higher disease risk; a gain of 44 to 88 pounds was linked to a 65 percent greater disease likelihood than those who gained fewer than 10 pounds.

The study doesn't prove that gaining weight in early adulthood causes colorectal cancer—only that the two appear to be linked. More research is also needed to see if men are at the same risk. However, this is another step in figuring out why colorectal rates are rising among younger patents.

Current screening guidelines
Without screening, most people under the age of 50 won’t know they have colorectal cancer until symptoms show up, and by then it has probably already spread, says Dr. Kaplan. At later stages, younger people who undergo colorectal cancer surgery are more likely to get potentially debilitating chemotherapy after the operation, but are no more likely to survive, according to a January 2017 study published in JAMA Surgery.

While the ACS did lower their recommended screening age for people at average risk, the US Preventive Services Task Force guidelines still recommend starting screenings at age 50. Those at a higher risk may require earlier screening. “People with a family history of colon cancer or people with polyps will probably be screened earlier than age 50 anyway,” says Kaplan.

They're not the only ones. “Higher rates are seen in people of lower socioeconomic status, possibly due to lower physical activity, unhealthy diet, smoking, obesity, and lower screening rates,” says Julia Saylors, MD, a medical oncologist with Trident Medical Center. And, African Americans have the highest rates of colorectal cancer of any ethnic group in the US. That could be partially due to genetic factors, but also because they’re less likely to be screened, says Saylors.

The ACS says the most important thing is to get screened, no matter which test you choose, and there are several options.

  • Colonoscopies should be done every 10 years.
  • Fecal tests need to be repeated every one to three years, depending on the specific test used.
  • CT colon scans and flexible sigmoidoscopies are done every five.

What you can do
If you have an increased risk of colorectal cancer or other types of cancer, talk to your doctor about when you should start screening. Also, be aware of colorectal cancer symptoms and see your doctor if you have:

  • Blood in your stool
  • Narrow stool
  • Change in bowel habits
  • Unexplained weight loss
  • Fatigue or weakness
  • Cramps or bloating 

No matter your age, healthy habits can reduce your risk of colorectal cancer. Physical fitness is a good start. One study found that the most physically fit participants were 44 percent less likely to get colorectal cancer than the least physically fit participants. Other ways to reduce your risk of colorectal cancer include:

  • Eating a high-fiber, low-fat diet and limiting red and processed meat
  • Drinking alcohol sparingly
  • Maintaining a healthy weight
  • Not smoking 

Take the first steps to growing younger and healthier with the RealAge Test.

This article was updated on October 17, 2018.