Colon cancer, or colorectal cancer, occurs when a group of cells in the large intestine begin to divide and grow uncontrollably. Uncontrolled cell division is dangerous because growing cells can form clumps and spread to other parts of the body. Cancerous cell masses can cause blockages in the digestive system, lungs, or blood vessels and can also upset chemical balances throughout the body.

What is the colon?

As noted above, the colon is also known as the large intestine. Before leaving the body, stool passes through the colon as the last step in the digestion process. In case you are unfamiliar with the anatomy of the digestive system, here is a helpful description.

Colon cancer is the third most responsible cause of cancer-related deaths worldwide. About one in 23 men and one in 25 women develop colon cancer in their lifetimes. Fortunately, colon cancer survival rates are currently on the rise.

• From a 2018 study (“Colorectal Cancer—Statistics”, 2019), the overall five-year colon cancer survival rate is 64% (i.e., 64% of people lived at least five years after their diagnosis)


• If colon cancer is diagnosed at an early stage, the five-year survival rate is 90%

If colon cancer is diagnosed at a more advanced stage, the five-year survival rate is 71%

State-of-the-art treatments such as those offered at South Texas Oncology and Hematology for Cancer Care are helping to detect and beat colon cancer. For more details on cutting-edge treatments or visit South Texas Oncology and Hematology services page.

Additional Resources

Statistical report of colon cancer survival rates
Description of the anatomy of the digestive system (Cleveland Cliniclivescience.com)

Colon cancer generally begins with the formation of non-cancerous polyps in the colon. A polyp is a small lump of cells, usually less than half an inch wide. Untreated polyps can eventually become cancerous. The cancer can then expand into the colon wall and spread throughout the body through the circulatory system (i.e., the blood) or the lymphatic system (i.e., the lymph, a fluid that cleans out unwanted cells in the body). About 10% of patients with colon cancer have a hereditary course of the disease.

Additional Resources

Further explanation of the lymphatic system (LiveScience)

Symptoms are seldom apparent in the earliest stages of colon cancer. To help catch colon cancer early on, doctors recommend colon screenings starting at age 50. Ask your doctor when to begin colon screenings depending upon your personal situation. Risk factors like race, personal medical history, and family medical history can increase your chances of getting colon cancer earlier and may necessitate colonoscopy screening before age 50 for cancer detection and prevention.

More advanced stages of colon cancer might present the following symptoms (Simon, 2019):

• Diarrhea or constipation that lasts longer than a few days
• Not feeling bladder relief after urinating or defecating
• Dark stools
• Blood in the stool
• Cramping, gas, or other abdominal (belly) pain
• Weakness/fatigue
• Unintentional weight loss

Keep in mind that issues other than colon cancer could cause the above symptoms. If you are experiencing any of them, consult a doctor for diagnosis and treatment.

Here are some of the leading treatments for colon cancer, all of which are available at South Texas Oncology and Hematology for Cancer Care:

• Surgery - Surgery is the primary treatment method for colon cancer. START surgeons have mastered any form of colon cancer surgery you might need. Standard colon cancer surgeries include:
  
  
  • Polypectomy - In earlier stages of colon cancer, a polypectomy removes polyps in the colon.
  
  
  • Local Excision - Also in the early stages of colon cancer, local excisions remove just the cancerous areas of the colon.
  
  
  • Colectomy - For more advanced cases of colon cancer, this procedure removes portions of the colon (partial colectomy) or the entire colon (total colectomy) containing cancerous cells.


• Anti-Cancer-Drugs - Most colon cancer treatments involve taking medication. South Texas Oncology and Hematology for Cancer Care provides comprehensive on-site pharmacy services including medication pick-up, counseling, financial aid, prior authorization processing for insurance claims, and home delivery.
  
  
  • Patients with colon cancer can be treated with several different medications. When the surgeon has removed all visible cancer from the patient, mediation is sometimes given to prevent cancer from coming back. This is called adjuvant chemotherapy. When the colon cancer cannot be completely removed, chemotherapy can be used to slow the progress of the disease and prolong a person’s life.
  
  
  • Capecitabine is a medication used to treat patients with colon cancer in both settings and physicians at START played a role in its development (reference 13). Another drug that is often used for colon cancer treatment is irinotecan and doctors at START played a prominent role in the development (reference 14 and 15). A new drug used for the treatment of some forms of colon cancer that can be identified with genetic tests is Pembrolizumab. The first person in the world to receive this drug was treated at START (reference 16).

Generally, each colon cancer patient takes a combination of different medications. These pharmaceutical treatments include:

• Chemotherapy - Chemotherapy drugs target quickly dividing cells (like cancer cells) and destroy them. Chemo is particularly useful when treating cancer in later stages because it can eliminate cancer cells throughout the whole body. More than half of cancer treatments involve some degree of chemotherapy, either to completely remove the cancer or to slow symptoms.


• Targeted Therapy - Targeted drug therapy is a type of chemotherapy designed to specifically attack the cancer cell itself or other molecules that enable cancer cells to grow. In some cases, targeted therapies cause fewer side effects than other treatments because they are better at addressing cancer cells and leaving healthy cells alone.


• START Center Oncologists are leaders in international cancer research and conduct the world’s largest oncology program in Phase I clinical trials for anti-cancer medications. (Phase I trials consist of the first round of research trials for new medications with a select group of participants.) The researchers at START have access to the very latest promising new anti-cancer medications. Interested in participating in cancer treatment research and getting access to cutting-edge medications? Complete this online form to learn more about whether early phase drug trials would be valuable to you.


• Genetic Testing - What is genetic testing? Each cell in the body, including a cancerous cell, contains a copy of your DNA. By sequencing the DNA found in cancerous cells, the cancer specialists at START employ a series of tests and genetic markers to identify which anti-cancer drugs are most likely to be effective, thereby saving weeks to months of treatment and avoiding unnecessary side effects. Hereditary disease testing is also available. Use our online form to request an appointment.


• Radiation - Hitting cancer cells with high-energy particles can damage a cancer cell’s DNA, which prevents the cancer from replicating and growing. For colon cancer cases, radiation is generally only an option when a patient is too sick for surgery. It is also typically used to relieve symptoms, but not to cure the cancer.

The stages of colon cancer determine the type of treatment a doctor prescribes. Below are general treatment patterns for the different stages of colon cancer (reference 12):

• Stage 0 - At this stage, the cancer is still contained within the inner lining of the colon. Surgery is usually the only treatment. A doctor might recommend a polypectomy, a local incision, or a partial colectomy if the cancerous area is too big to be removed by local incision.


• Stage 1 - By Stage 1, the cancer has penetrated the wall of the colon but has not yet spread outside it. A polypectomy is sometimes appropriate if the cancer can be easily removed; for more complicated cases, a partial colectomy is generally conducted.


• Stage 2 - At this point, the cancer has progressed through the colon wall and into the surrounding tissues, but it has not yet reached the lymph nodes. A partial colectomy is generally called for at this stage. An oncologist may also prescribe chemotherapy if there are circumstances that complicate the colectomy.


• Stage 3 - In this state, the cancer has spread to nearby lymph nodes, but not yet to other parts of the body. Usually, this stage requires a partial colectomy and removal of the cancerous lymph nodes, followed by chemotherapy. If a patient is insufficiently healthy enough for surgery, radiation is also an option.


• Stage 4 - At the final stage of colon cancer, cancer has spread to organs throughout the body. Surgery is generally not an effective option since the cancer is so dispersed. Chemotherapy is the main treatment, sometimes combined with surgery before or after. Radiation and targeted therapies might also relieve symptoms.

Additional Resources

General treatment patterns at various stages of colon cancer
Chemotherapy
Targeted Therapy

Before colon cancer reaches an advanced stage (and has spread throughout the body), it usually shows no symptoms. This is why it is so important to begin regular colon screenings at age 50. As previously mentioned, some risk factors increase the likelihood of developing colon cancer earlier, so you should ask your doctor when you should begin regular colon screening. Use this online form to request an appointment

The risk factors for colon cancer include a mix of both genetic and lifestyle factors.

Genetic Risk Factors

• Syndrome-causing genes - about 5% of colon cancers are due to two inheritable diseases: hereditary nonpolyposis colorectal cancer (HNPCC or Lynch Syndrome) and familial adenomatous polyposis (FAP). Individuals with a gene for HNPCC are 80% more likely to develop cancer, while those with FAP are 100% likely to develop cancer if they do not undergo a total colectomy before age 40. Sometimes FAP is inherited, but in about one-third of cases, it is simply the result of a newly arisen mutation in the individual (reference 4). Physicians at START can help you find a genetic counselor to determine if you have one of these problems.


• African-American Ancestry - African-American males are 12.9% more likely to develop colon or rectal cancer than white males, and African-American females are 7.9% more likely to develop colon or rectal cancer than white females (reference 3).


• Jewish Ancestry - People of Jewish ancestry are more likely to develop diseases like HNPCC, FAP, Crohn’s disease, and others.


• Family History of Colon Cancer (reference 10)

Lifestyle/Environmental risk factors:

• Obesity - Some studies suggest that being overweight might raise the likelihood of developing polyps by 10%. In other studies, 50% of patients with cancer had an abnormally high body mass index (BMI) (reference 11).


• High-fat, low-fiber die - Studies show that increasing the fiber in your diet could lead to a 14%-21% decrease in the likelihood of developing colon cancer (reference 5). High fat is also strongly correlated with a higher colon cancer risk (reference 1).


• Not enough exercise - Strong evidence suggests that a sedentary lifestyle dramatically increases the chance of developing colon cancer (reference 6).


• Diabetes/insulin resistance - Studies differ, but some studies show that people with Type II diabetes are more likely to develop colorectal cancer.


• Inflammatory bowel disease - IBD can refer to either Crohn’s disease or ulcerative colitis, two diseases in which the digestive system has a strong inflammatory response to certain foods.


• Smoking - Not only does smoking increase the likelihood of developing cancer, one study showed that current smokers had a 21% higher rate of cancer death compared to those who had never smoked.


• Alcohol - Heavy drinking has been shown to have a significant correlation with colon cancer (reference 8; reference 7).

Additional Resources

Inherited diseases that increase the risk of colon cancer
Further explanation of the lymphatic system

While not all cases of colon cancer are preventable, several lifestyle changes may decrease the likelihood of getting colon cancer:

• Regular colonoscopies - You can detect polyp growth before it becomes cancerous. Ask your doctor about when you should schedule a colonoscopy on an ongoing basis.
  
• Increase your fiber - Vegetables, fruits, and whole grains are great options.


• Eat less red meat and processed meat - These meats tend to be particularly high in fat.


• Maintain a healthy weight - Weight can often be stabilized through a healthy diet and with regular exercise.


• Exercise - Most experts recommend at least 30 minutes of physical activity every day through recreational activities or even just walking more.


• Limit alcohol intake


• Avoid smoking

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