Colorectal cancer is one of the most common cancers in the United States. About one in 23 women (one in 21 men) will develop cancer of the colon or rectum in their lifetimes. It also is the second leading cause of cancer deaths when men and women are considered together and is the third leading cause of cancer death among women.
There are regional differences in colorectal cancer’s incidence and mortality throughout the country, with the lowest rates occurring among those living in Western states, and survival rates lowest among African Americans.
The good news is that the disease is not only highly beatable and treatable, but also highly preventable. Regular screening and removal of polyps can reduce colorectal cancer risk by up to 90 percent. But unfortunately, fear, denial and embarrassment keep many people from being screened.
When colon cancer is caught and treated in stage I, there is a 92 percent chance of survival at five years. Once the cancer is larger and has spread to the lymph nodes, however, the five-year survival rate drops to between 53 and 89 percent, depending on the number of nodes involved. If the cancer has already spread to distant parts of the body such as the liver or lungs, the five-year survival rate goes down to 11 percent.
The large intestine is the last section of the digestive tract and consists of the colon and rectum. The colon is four to six feet long, and the last seven to nine inches of it is called the rectum. After food is digested in the stomach and nutrients are absorbed in the small intestine, waste from this process moves into the colon, where it solidifies and remains for one or two days until it passes out of the body.
Sometimes the body produces too much tissue, ultimately forming a tumor. These tumors can be benign (not cancerous) or malignant (cancerous). In the large intestine, these tumors are called polyps. Polyps are found in about 30 percent to 50 percent of adults. People with polyps in their colon tend to continue producing new polyps even after existing polyps are removed.
The exact cause of colon cancer is unknown, but it appears to be influenced both by hereditary and environmental factors. People at an increased risk of colon cancer include those with either a personal or family history of colorectal cancer or polyps, individuals with a long-standing history of inflammatory bowel disease and people with familial colorectal cancer syndromes. Some of those at high risk may have a 100 percent chance of developing colorectal cancer.
Specific risk factors include:
- Personal History: A personal history of colorectal cancer, benign colorectal polyps which are adenomas or sessile serrated polyps, or chronic inflammatory bowel disease (e.g., ulcerative colitis and Crohn’s disease) puts you at increased risk for colorectal cancer. In fact, people who have had colorectal cancer are more likely to develop new cancers in other areas of the colon and rectum, despite previous removal of cancer.
- Heredity: If one of your parents, siblings or children has had colorectal cancer or a benign adenoma, you have a higher risk of developing colorectal cancer. If two or more close relatives have had the disease, you also have an increased risk; approximately 5 to 10 percent of all people with colorectal cancer fall into this category.
The most common genetic conditions that increase risk for colon cancer are familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC).
- Familial adenomatous polyposis (FAP). People who have inherited the FAP syndrome may develop hundreds to thousands of polyps in their colon and rectum at a young age, usually in their teens or early adulthood. These polyps are all adenomas. By age 40, almost all patients with FAP will develop colon cancer if they don’t have preventive surgery. Most people who have this syndrome begin annual colon examinations while in elementary school, and many choose to have their colon and rectum removed before cancer develops. FAP is rare, accounting for about 1 percent of all cases of colorectal cancer.
- Hereditary non-polyposis colon cancer (HNPCC). Also known as Lynch Syndrome, HNPCC is a more common form of inherited colon cancer, accounting for about 2 percent to 4 percent of all colorectal cancer cases. While it is not associated with thousands of polyps, polyps are present and grow more quickly into cancer than in patients without HNPCC. Colon cancer in people with HNPCC also develops at a younger age than sporadic colon cancer, although not as young as in those with FAP.
Cancers in patients with HNPCC tend to be fast growing and respond less to chemotherapy. The lifetime risk of colon cancer in people with HNPCC may be as high as 80 percent. People with HNPCC are also at an increased risk for other types of cancer, including cancer of the ovary, endometrium, stomach, pancreas, bile duct, brain, kidney, ureters, and bladder.
- MUTYH-associated polyposis (MAP): People with this syndrome, which is caused by mutations in the gene MUTYH, develop colon polyps that are destined to become cancerous if they are not removed. Their colonoscopy findings may be similar to FAP with hundreds to thousands of polyps or not. People with MUTYH are also at increased risk of cancers of the small intestine, skin, ovary and bladder.
If you have a history of adenomas or colon cancer or suspect you have a family history of the disease, you should discuss this with your health care professional because you may need to begin screening for the disease at a relatively young age. In some cases, you may wish to undergo genetic testing.
- Age: The risk of colorectal cancer increases with age. Ninety percent of new cases of colorectal cancer in the United States are in people over 50. Clinical studies indicate that when screened for the disease, African Americans tend to be diagnosed with colorectal cancer at a younger age than Caucasians.
- Race: African Americans are more likely to get colorectal cancer than any other ethnic group. Compared to Caucasians, African Americans are about 10 percent more likely to develop colorectal cancer. Unfortunately, they also are more likely to be diagnosed in advanced stages. As a result, African Americans are more likely to die from colon cancer than Caucasians. In 2013, the rate of death from colon cancer among African Americans was about 32 percent greater than that among whites.
- Diet: Eating a diet high in processed meats (hot dogs and some lunch meats) and red meats (lamb, beef or liver) may increase your risk of developing the disease. Avoiding red meat and eating a low-fat diet rich in vegetables, fruit and fiber (e.g., broccoli, whole grains and beans) may reduce your risk of developing colorectal cancer. Some studies suggest that boosting calcium intake helps prevent colon cancer. Until further studies are done, men should keep their intake below 1,500 milligrams because of the increased risk of prostate cancer associated with high levels of calcium. Some research has also shown that vitamin D, which you can get from foods, sun exposure or a pill, can help lower colon cancer risk, but because of the increased risk of skin cancer with sun exposure, most health care professionals don’t advocate getting more sun to reduce colorectal cancer at this time. Other studies suggest that taking a multivitamin that contains folic acid may lower colon cancer risk, but other studies have suggested folic acid may help existing tumors grow, so more study is needed in this area. There is some research suggesting that a diet high in magnesium may decrease colon cancer risk, especially in women. More research is necessary to find out if this link exists.
- Lifestyle: Regular exercise is a key weapon in the fight against colorectal cancer. Another significant risk factor in colorectal cancer is smoking. Get help quitting if you can’t do it on your own. And keep your alcohol intake to one drink a day or less (two drinks a day or less for men).
- Obesity: Obesity is an epidemic in the United States and has been associated with many types of cancers, including colorectal cancer. There is a strong link between higher BMI (body mass index) and waist circumference and colon cancer risk in men and a weaker association seen in women. High levels of insulin and insulin-like growth factor may play a role in development of colon cancer in obese people. Weight loss has been shown to reduce the risk of colon cancer.
Symptoms of colorectal cancer include:
- Change in bowel habits (diarrhea, constipation or narrow stools for more than a few days)
- Urgency for a bowel movement or feeling like you need to move your bowels even if you just did
- Blood in the stool
- Stomach pain
- Weakness and/or fatigue
Contact your health care professional if you experience one or more of these symptoms.
Colorectal Cancer Stages
As with all cancers, there are various stages of colon cancer:
- Stage 0: Abnormal (dysplastic) cells have been found in the innermost lining (mucosa) of the colon. This stage is also known as carcinoma in situ or intramucosal carcinoma, and there is a very small chance these cells have spread, so this stage is not considered to be invasive cancer.
- Stage I: Cancer has spread to the inside lining of the colon but hasn’t spread beyond the colon wall or rectum.
- Stage II: Cancer has spread through the colon or rectum and may invade surrounding tissue, but no lymph nodes are involved.
- Stage III: Cancer has spread to the lymph nodes, but not to distant sites.
- Stage IV: Cancer has spread to other distant parts of the body, such as the liver or the lung.
Surgery is often required to treat colorectal cancer. The surgical procedure used depends on where the cancer is located. Most patients who undergo surgery for colon cancer have an open abdominal operation, where the surgeon makes an incision in the abdomen and removes the tumor and any affected lymph nodes. In some cases, however, a procedure called laparoscopic colon cancer resection may be used. Like open abdominal surgery, laparoscopic surgery is performed under general anesthesia, but multiple, much smaller incisions are made, which leads to a shorter recovery time. Studies have shown similar results when open abdominal and laparoscopic techniques are used to remove colon cancer. A surgeon experienced at laparoscopic surgery should perform these surgeries.
Occasionally, early cancerous changes may be limited to a portion of an otherwise noncancerous polyp. In these cases, it is sometimes possible to remove some very early colon cancers during a colonoscopy.
If part of the colon needs to be removed due to a larger cancerous tumor, the surgeon will remove the affected portion and leave as much of the healthy colon behind as possible. In rectal cancer, the rectum is removed.
In many cases, the surgeon will be able to reconnect the healthy portions of the colon and rectum, which allows waste to flow through the colon to the rectum. If this is not possible, you may need to have a colostomy. A colostomy (stoma) involves creating a hole in the wall of abdomen to which an end of your colon is attached so you can eliminate waste into a special bag. Depending on the situation, a colostomy may be temporary or permanent.
You may be referred to an enterostomal therapist (a health care professional, often a nurse, trained to help people with their colostomies) as part of your initial workup. The enterostomal therapist can address concerns about how a colostomy might affect your daily activities.
Even after colon cancer has been completely removed with surgery, cancer cells can remain in the body and cause relapse. To kill these cells and decrease the chances of a relapse, health care professionals use chemotherapy. Not all people need chemotherapy after surgery. Those most likely to receive chemotherapy are people at risk for recurrence, namely, those with stage III colon cancer or high risk stage II.
For some rectal cancers, chemotherapy is given along with radiation therapy in an attempt to shrink the tumor before surgery. This is called neoadjuvant chemotherapy.
Several chemotherapy drugs are used to treat colon cancer. In many cases, two or more of these drugs are combined for more effective treatment:
- 5-Fluorouracil (5-FU): 5-FU is often given together with another chemotherapy drug called leucovorin (folinic acid).
- Capecitabine (Xeloda): A chemotherapy drug in pill form, Xeloda changes to 5-FU once it reaches the tumor.
- Irinotecan (Camptosar)
- Oxaliplatin (Eloxatin)
- Trifluridine and tipiracil (Lonsurf): a combination drug in pill form.
Individuals with advanced colon cancer may receive targeted drugs that help stop cancerous tumors from growing. These drugs include bevacizumab (Avastin), cetuximab (Erbitux) and panitumumab (Vectibix). They may be given alone or together with chemotherapy.
Not all people benefit from targeted medications. Researchers are currently examining who are most likely to respond. Until then, health care professionals will continue to weigh the risks and benefits of targeted drugs before they prescribe them for people with advanced disease.
Radiation therapy may benefit some people with rectal cancer, but it is not usually used in the treatment of early stage colon cancer. Like chemotherapy, radiation may be helpful for patients who are at high risk of cancer recurrence, for instance if the cancer has spread to nearby organs. In general, the goal of radiation is to reduce chances of colon cancer recurrence rather than to improve survival.
For those whose colorectal cancer has metastasized to a few areas in the liver, lungs or elsewhere in the abdomen, surgically removing or destroying these metastases can increase survival.
If the cancer comes back in only one part of the body, you may need surgery again. If it has spread to several parts of the body, you may receive chemotherapy and/or radiation therapy.
The most important line of defense against colorectal cancer is screening for colorectal cancer. You should follow the established guidelines for screening procedures so that any precancerous polyps can be removed before they turn into cancer and, if cancer exists, it can be detected at the earliest possible stage. If you are at average risk of colorectal cancer, the American Cancer Society recommends that all women and men over the age of 50 undergo one of the following:
- annual fecal occult blood test
- flexible sigmoidoscopy every five years
- double contrast barium enema every five years
- colonoscopy every 10 years unless you are African American, in which case your screening can begin at age 45
- virtual colonoscopy (CT colonography) every five years
- stool DNA test every one to three years
Any positive screening test should be followed by an appropriate and complete diagnostic evaluation of the colon including a colonoscopy with biopsies, if necessary.
If you are at an increased risk of colorectal cancer or adenomas because of a family history of cancer or polyps, you should follow the above recommendations and also:
- Begin colorectal screening at age 40, or 10 years before the youngest case of colon cancer in the immediate family.
- Discuss genetic counseling and/or testing with your health care professional.
If you are at an increased risk for colorectal cancer for a reason other than family history, such as a personal history of inflammatory bowel disease, you may also need to begin screening before age 50. Screening recommendations vary based on your particular risk factors; discuss your individual screening schedule with your health care professional.
Modifying your diet and exercise may help decrease your risk of forming colon polyps and/or colon cancer. A diet rich in vegetables, fruit and fiber and low in fat may reduce the risk of developing colon cancer. Some suggest that increasing intakes of calcium and vitamin D can help prevent colon cancer. (Men should keep their intake below 1,500 milligrams because of the increased risk of prostate cancer associated with high levels of calcium.) Calcium can be found in dairy products, calcium-fortified products such as orange juice, soy and dark green vegetables. Other research has shown that taking a multivitamin containing folic acid (a B complex vitamin) decreases the risk of colon cancer, but other studies show folic acid may help existing tumors to grow, so more study is needed. There is some research suggesting that a diet high in magnesium may decrease colon cancer risk, especially in women. More research is necessary to find out if this link exists.
Regular exercise is important in preventing colon cancer. Experts say that vigorous exercise is not necessary. Instead, just incorporate more activity into your daily routine, such as taking the steps instead of the elevator or parking your car farther from the building you are entering. Overall, the American Cancer Society recommends 150 minutes of moderate physical activity or 75 minutes of vigorous physical activity per week.
It is also advisable to drink alcohol only in moderation (no more than one alcoholic beverage per day for women, for a total of less than seven drinks per week, and no more than two alcoholic beverages for men, for a total of less than 14 drinks per week) and abstain from tobacco use.
Results from multiple studies show that people who regularly take aspirin and other non-steroidal anti-inflammatory medications (NSAIDS) have a lower risk of colorectal cancer and adenomatous polyps. However, the risk of stomach ulcers and other side effects associated with aspirin and NSAIDS may outweigh the benefits. Therefore, experts do not recommend people at average risk of colorectal cancer take NSAIDS as a prevention strategy. There may be some value of NSAIDS in people at increased risk of colorectal cancer, which is being studied. The drug celecoxib (Celebrex) has been approved by the United States Food and Drug Administration (FDA) for reducing polyps in people with FAP. Celebrex may cause less bleeding in the stomach than other NSAIDs, but it may increase risk for heart attack and stroke.
Discuss the potential risks and benefits of taking NSAIDS with your health care professional.
Facts to Know
- The American Cancer Society estimates that about 95,270 new cases of colon cancer and 39,220 new cases of rectal cancer will be diagnosed in 2016. Combined, these cancers are predicted to cause about 49,190 deaths during 2016.
- While colorectal cancer is the second leading cause of cancer deaths when men and women are considered together and is the third leading cause of cancer death among women, incidence in the United States has been decreasing, perhaps due to improved screening methods.
- The risk of developing colorectal cancer is highest among those with a family history of colorectal cancer or adenomatous polyps and those who have inflammatory bowel disease.
- Except for those with hereditary conditions that may predispose them to developing colorectal cancer relatively early in life, 90 percent of all cases occur after the age of 50.
- Tumors that grow in the large intestine are called polyps. A biopsy determines if the polyp is benign (not cancerous) or malignant. Benign polyps can be precancerous (adenomatous and sessile serrated) or not precancerous (hyperplastic). Thirty percent to 50 percent of the population has polyps. Over the course of about 10 years, adenomatous polyps can become cancerous if they are not removed.
- Undergoing appropriate screening for colorectal cancer can decrease death rates from this cancer by up to 90 percent. Colorectal cancer screening is designed to detect and remove precancerous polyps (adenomas and sessile serrated polyps) before they turn into cancer and to diagnose cancer at the earliest stages.
- If you or a close relative were diagnosed with colon cancer at age 45, then other members of your family should begin screening around age 35. If you have a close relative with colorectal cancer, you should begin screening at the age of 40 or 10 years before the age at which the youngest relative was diagnosed with cancer.
- Cancer specialists are using more aggressive strategies to make sure cancer does not return after surgery. You may receive both chemotherapy and radiation therapy to increase your chances of a complete cure. These treatments destroy microscopic accumulations of cancer cells that cannot be seen or removed during surgery.
- When colon cancer is caught and treated in stage I, there is a 92 percent chance of survival at five years. Once the cancer is larger and has spread to lymph nodes, the five-year survival rate drops to 53 to 89 percent depending on the number of nodes involved If the cancer has already spread to distant parts of the body such as the liver or lungs, the five-year survival rate goes down to 11 percent.
- You may be able to reduce your risk for colorectal cancer by eating a diet high in fiber and low in fat, getting plenty of exercise, limiting your alcohol intake to one drink or less a day, losing weight if you are obese, taking calcium and having regular colorectal cancer screenings.