Colorectal Cancer: Understanding Risks, New Screening Guidelines and Lifestyle Recommendations

Colorectal Cancer

Any cancer that starts in the colon or rectum is considered colorectal cancer. According to the American Cancer Society, or ACS, in 2019 there will be an estimated 145,600 new colorectal cancer cases in the United States (78,500 men and 67,100 women) and 51,020 deaths from the disease (27,640 men and 23,380 women). Improved survival rates over the last 30 years may be attributed in part to increased screening, changes in risk factors and better treatment options.

Colorectal cancer is somewhat more common in men than women, with incidence rates of 45.2 percent and 34.3 percent, respectively, from 2011 to 2015. The median age at diagnosis is 63 to 68 in men and 63 to 72 in women. However, proportionally more and more cases are being seen in younger people.

Racial and ethnic disparities in colorectal cancer are complex but attributable in part to socioeconomic status. Less income and education are predictors of higher colorectal cancer risk and are associated with differences in screening as well as modifiable risk factors. From 2009 to 2013, colorectal cancer rates were 20 percent higher and death rates were 40 percent higher in blacks than whites.

Updated guidelines and screening
In May 2018, the ACS changed its guidelines for colorectal cancer screening based on research showing an increase among younger adults, despite an overall decline nationally. In 2013, 11 percent of diagnoses were in people younger than 50, compared with 5 percent in 1990. Compared to adults born in 1950, those born in and around 1990 have twice the risk of colon cancer and four times the risk of rectal cancer. ACS now recommends screening begin at age 45 for people at average risk, meaning those who have no personal or family history of colorectal cancer or certain polyps; no personal history of inflammatory bowel disease; no confirmed or suspected hereditary syndromes that increase risk for colorectal cancer; and no personal history of radiation treatment to the abdomen or pelvis for prior cancer.

The ACS recommends individuals “in good health” and with a life expectancy of more than 10 years receive continued screening through age 75. For adults ages 76 to 85, screening should be assessed on an individual basis, considering personal preference, medical history and life expectancy. For those older than 85, screening is not recommended.

The U.S. Multi-Society Task Force on Colorectal Cancer, or USMSTF, also updated its guidelines in May 2018 to recommend beginning screening at age 45. The United States Preventive Services Task Force recommends screening starting at 45 for those who are at average risk for colorectal cancer and continuing until 75. These guidelines were updated in May 2021.

All people at high risk of colorectal cancer should discuss screening with their physicians.

Screening involves one or more tests or procedures, depending on a person’s medical history and preferences. There are three main types of visual exam: colonoscopy, which typically is performed every 10 years; CT colonography, or virtual colonoscopy, which is performed every five years; and flexible sigmoidoscopy, which is performed every five years. In addition, three stool-based tests may be used: high-sensitivity fecal immunochemical test and high-sensitivity guaiac-based fecal occult blood test, which are performed yearly; and the multi-targeted stool DNA test, which is performed every three years.

Identifying symptoms
Early stage colorectal cancer often is asymptomatic. Colorectal cancer symptoms may include gas, bloating, constipation, diarrhea, changes in bowel habits, blood in stool or dark stools, iron deficiency anemia, weakness, fatigue and unexplained weight loss. Each of these symptoms may be attributed to many causes besides cancer, such as irritable bowel syndrome and stress. Any of these symptoms warrants a visit to the doctor.

According to the USMSTF, rectal bleeding and unexplained iron deficiency anemia in particular have “substantial predictive value” and should be thoroughly evaluated. Unfortunately, many people, especially younger adults, don’t seek medical attention right away, and when they do, misdiagnosis is common. Based on a recent international survey including nearly 1,200 youngonset colorectal cancer patients, 41 percent waited at least six months before seeing a doctor regarding their symptoms and 67 percent saw at least two physicians before receiving the correct diagnosis.

According to a 2017 study of nearly 500,000 adults in the U.S., adults younger than 55 are 58 percent more likely to be diagnosed with late-stage colorectal cancer than older people. The study authors say this is “largely due to delayed follow-up on symptoms, sometimes for years, because cancer is typically not on the radar of young adults or their providers.”

Healthy lifestyle habits and risk reduction
While no cancer is 100-percent preventable, attention to diet and other lifestyle factors can help reduce risk. Specific to colorectal cancer, research suggests:

Limit red meat and avoid processed meat. Eating more than 18 ounces per week of red meat (including beef, pork and lamb) has been associated with a higher risk for colorectal cancer. The American Institute for Cancer Research recommends avoiding processed meats (those that have been preserved by smoking, salting, curing or adding other preservatives, including sliced turkey and bologna deli meats, bacon, ham and hot dogs). RDNs can encourage eating tofu, tempeh, beans, nuts, seeds and other plant-based protein sources to replace any or all meats.

Eat fiber-rich foods. Several studies suggest eating fiber-rich foods, including vegetables, fruits and whole grains, is associated with a lower risk for colorectal cancer.

Limit alcoholic drinks. Evidence shows an increased risk for colorectal cancer with moderate to heavy alcohol consumption. One metaanalysis showed a 20-percent higher risk for colon cancer among people who had two to three drinks per day and a 50-percent higher risk with four or more drinks per day, compared with occasional or no alcohol use. One drink is about 5 ounces of wine, 12 ounces of beer or 1.5 ounces of distilled liquor. RDNs can counsel clients on minimizing alcohol appropriately.

Don’t smoke cigarettes or use other tobacco products. In a large prospective study, incidence of colorectal cancer was about 30 percent higher in current and former smokers compared with lifelong nonsmokers. Colorectal cancer risk decreases over time after smoking cessation.

Achieve and maintain a healthy body weight. Excess body fat is associated with a higher risk for colorectal and other cancers. While overweight and obesity are multifactorial and not the result of diet alone, RDNs can counsel people on balanced, sustainable, calorieappropriate nutrition as one way to promote a healthy weight and overall wellness.

Be physically active. Higher levels of physical activity, including structured exercise and recreational activity, are associated with a lower risk for colon cancer, though this association has not been seen with rectal cancer. Additionally, people with a previous colorectal cancer diagnosis who engage in regular physical activity have a lower risk of dying from colorectal cancer. Given the well-known physical and mental health benefits of regular physical activity, RDNs can routinely promote this lifestyle practice.

Nutrition during and after treatment
Treatment for colorectal cancer may include surgery, chemotherapy or targeted therapy, and radiation therapy. “Patients receiving care for colorectal cancer vary significantly in their symptoms and side effects,” says Meghan Garrity, MS, RD, CSO, CDN, a dietitian at Memorial Sloan Kettering Cancer Center in New York City. “There’s no one-size-fits-all nutrition intervention during active treatment or after treatment is complete.”

Depending on the tumor site, surgery can involve the removal of any part of the colon and rectum. Nutrition-related complications may include short bowel syndrome, malabsorption, dehydration, adhesions and intestinal obstruction. Depending on symptoms and oral tolerance, it may be helpful for patients to eat small frequent meals; drink fluid between meals rather than with meals; minimize gas-producing foods and high-fiber foods; and limit the amount of high-fat foods and added sugars they eat. RDNs can help patients get adequate calories and protein to minimize the loss of lean body tissue and enough fluids to avoid dehydration.

Chemotherapy may be given before or after surgery and often involves a combination of medications. Nutrition-related side effects may include decreased appetite, nausea, vomiting, diarrhea, constipation, abdominal pain, mouth sores or mucositis, changes in taste, difficulty swallowing, a suppressed immune system and fatigue. Diet modifications can be used in addition to medications for symptom management; for example, a tailored diet for diarrhea along with antidiarrheal drugs. Some side effects of radiation treatment to the abdominal area may be similar to those that arise during chemotherapy.

If a patient is experiencing nausea, RDNs can encourage small amounts of food and drinks at a time, drinking hot or iced ginger tea and avoiding greasy, fatty and fried foods as well as strong food odors. Some people feel best eating cool, moist foods such as yogurt, watermelon, applesauce or smoothies; others may find relief with dry, bland foods such as soda crackers or plain toast.

To manage diarrhea, patients should minimize very high-fiber foods such as wheat bran, as well as spicy foods, caffeine, fruit juices and foods with added sugars or sugar alcohols. In some cases, electrolyte-enhanced drinks may be useful for hydration and repletion. Patients can eat plain toast or pasta, bananas, white rice and unseasoned cooked fish, eggs or chicken. Small portions of cooked vegetables and fruits may be better tolerated than raw.

Some patients have a general loss of appetite. RDNs can discuss having small amounts of food and drink at a time, homemade or commercially prepared smoothies and shakes, “breakfast for dinner” foods and easy-to-eat foods such as individual yogurt cups, granola bars or packets of nuts.

For patients experiencing fatigue, RDNs can similarly encourage easy-to-eat or prepared foods, shakes or smoothies, and small frequent meals and snacks. Additionally, patients may feel better eating more food earlier in the day and less in the evening, and should limit or avoid alcohol, excess caffeine and foods or beverages high in added sugars.

If a patient has mouth sores, dry mouth or difficulty swallowing, RDNs can encourage moist foods, soups, smoothies or shakes, blended or pureed foods, cool or room temperature foods, drinking through a straw to avoid irritating sores, avoiding alcoholic drinks and avoiding dry, crusty, spicy or highly acidic foods.

Maintaining good oral hygiene is important both during and after treatment. Certain therapies increase the likelihood of tooth decay, cause dry mouth and weaken oral health, with effects that persist even after active treatment is completed. RDNs should encourage patients and clients to brush their teeth, rinse their mouths, stay hydrated, avoid alcohol-based dental products, minimize added sugars and sweets, avoid chewing gum with sugar and receive regular professional dental care.

This article was updated on May 19, 2021, to reflect updated screening recommendations from the USPSTF.


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Cara Anselmo
Cara Anselmo, MS, RDN, is a nutritionist and certified yoga instructor in New York City. Follow Cara on Twitter.