Do you know in the recent decade more young people have developed colon and rectal cancer? According to studies, millennials have double the risk of colon and four times more risk of rectal cancer when compared to people born in 1950s. This trend has raised several questions about the lifestyle, environmental factors, and screening techniques of colorectal cancer (CRC). Till now, it is not clear why people, especially younger than 50 years get CRC. Keeping these facts in mind, the biggest focus is on preventing, detecting and treating CRC as early as possible.
Colon and Rectal Cancer
Colon and rectal cancer are abnormal growths in the colon and the rectum (parts of the lower region of the digestive system). These cancers have many common features, so they are usually grouped together as colorectal cancer.
Colorectal cancer is the third most common cancer in men and the second most common in women, globally. (1)In India, colon cancer is the eighth most common in men and ninth most common in women, whereas rectal cancer is on the ninth position in men and it doesn’t figure in top 10 cancer in women.(2)
According to World Health Organisation, about 36,687 men and 20,064 women were newly diagnosed with colorectal cancer in 2018. Also, 20,056 people died of rectal cancer and 19,548 died of colon cancer.
Causes and Risk Factors
Colorectal cancer occurs when the cells lining the colon or the rectum begin to grow and divide abnormally, resulting in the formation of a mass of tissue, known as a polyp. Not all polyps are cancerous, only some that continue to grow may become cancerous. The cancerous cells in the polyps may invade the other tissues and lymph nodes and metastasize to distant parts of the body.
The exact cause of colorectal cancer is not yet unknown. However, the following factors may increase the risk of colorectal cancer:
Non-modifiable Risk factors:
- Family history
- Personal medical history
- Inherited syndromes
Modifiable Risk factors:
- Diet rich in refined and processed foods
- Physical inactivity
- Alcohol consumption
Signs and symptoms of colorectal cancer:
CRC usually doesn’t cause any signs or symptoms immediately. But, if it does, then it might cause the following:
- Incomplete bowel emptying
- Narrower stools than usual
- Loose stools or constipation
- Blood in stools or rectal bleeding
- Abdominal pain/ cramps
- Frequent flatulence
Visit a doctor immediately, if these symptoms persist for more than two weeks.
Screening for CRC:
Regular screening is the only way to detect and beat CRC during the early stages. According to recent American Cancer Society guidelines, a person with an average risk of CRC must begin screening at 45 years and proceed until 75 years. After the first screening, the person is advised to have a screening every ten years.
People with a high risk of CRC must start screening before the age of 45 and should get screened more often.
Diagnosing CRC during the early stages improves the survival rate to about 90%. Initially, the patient’s history, including the information about the incidence of symptoms, family history of CRC or polyps, and personal medical history are collected. Later, a physical examination and a digital rectal examination are done.
Physical examination: It is performed to examine the abdomen and other parts of the body in order to detect any enlarged organs or abnormal masses.
Digital rectal examination: It is performed by inserting a lubricated, gloved finger in the rectum to detect the presence of any abnormal masses.
If the doctor suspects colorectal cancer then the following diagnostic tests are recommended:
Colonoscopy: It is performed both as a screening and confirmatory test for CRC. This test involves insertion of a colonoscope (a thin, long, tube-like instrument with a light, outlet for air, and camera) into the colon and the rectum to view any abnormalities.
CT Colonography: A colonoscope is inserted into the patient’s colon and air is passed to inflate the colon. The patient is now passed through the CT scanner, which takes multiple and detailed images of the colon and the rectum.
Stool tests: Stool samples are collected and examined to determine any abnormal signs of colorectal cancer. Faecal immunochemical test (FIT) or Immunochemical faecal occult blood test (iFOBT), Guaiac-based fecal occult blood test (gFOBT), and stool DNA test are some stool tests employed for diagnosing CRC.
Flexible Sigmoidoscopy: In this test, a sigmoidoscope (a thin, flexible, lighted tube fitted with a video camera) is inserted into the rectum and passed to the lower part of the colon to detect polyps or cancer.
Biopsy: If abnormalities are found in any of the diagnostic tests, a biopsy is advised. In this test, special surgical tools are passed inside the colon or rectum to collect a tissue sample. This tissue is further examined in the laboratory.
Blood test: People with CRC may experience bleeding that may result in anaemia. Additionally, it helps in determining the health of the kidney and the liver. Blood test might also be done to detect the presence of a chemical known as carcinoembryonic antigen, which might indicate CRC.
Staging of CRC:
Staging of cancer helps to know about the severity, size, extent and spread of cancer. The stage of CRC are as follows:
- Stage I: Cancer has grown through the inner lining and entered into the muscular layer of the colon or rectum.
- Stage IIA: Cancer has grown into colorectal wall.
- Stage IIB: Cancer has grown through the muscular layer of the colon and the rectum and extended to the lining of the abdomen.
- Stage IIC: The tumour has spread through colon or rectal walls and has invaded nearby structures.
- Stage IIIA: The cancer has grown through the walls of colon or rectum. It has spread to 1 to 3 lymph nodes or forms a tumour nodule in tissues around the colon or rectum.
- Stage IIIB: The cancer has grown through the wall of the colon/ rectum or to surrounding organs. It has spread to 1 to 3 lymph nodes or forms a nodule of tumour in tissues around the colon or rectum that do not appear to be lymph nodes.
- Stage IIIC: The cancer has grown through the wall of the colon/ rectum. It has spread to 4 or more lymph nodes.
- Stage IV: The cancer has spread to distant parts of the body.
The treatment of colorectal cancer depends on the location and stage of the cancer. Also, patient’s age, medical history, and overall health condition are also considered.
Treatment modalities for CRC include:
Surgery is the common treatment option for all stages of CRC. Surgery is done to remove the tumours and surrounding tissues where the cancer might have spread. Depending on the location and stage of the cancer the doctor might recommend any of the following surgeries:
Colon cancer surgeries:
- Open colectomy
- Laparoscopic colectomy
- Colon obstruction surgery
Rectal cancer surgeries:
- Local resection
- Total mesenteric excision
- Pelvic exenteration
Chemotherapy is the use of drugs to kill cancer cells. It is either given orally or in the form of intravenous injection. Chemotherapy is usually given after the surgery to prevent the recurrence of the cancer or before the surgery to shrink the tumour.
It involves usage of high-energy beams to shrink and destroy the cancer cells. Radiation therapy is usually combined with surgery/chemotherapy. For colorectal cancer, radiotherapy is usually used to target the rectal cancers than the colon cancers.
It involves administration of certain medicines to block the growth and spread of the cancer cells. Targeted therapy acts by inhibiting the action of specific molecules, enzymes, or proteins that are responsible for the growth and progression of cancer.
Immunotherapy boosts body’s natural defense system against cancer. It involves the use of substances derived or made from living organisms. Immunotherapy acts by recognizing and attacking cancer cells or by boosting the function of immune cells.
Prevention of Colorectal Cancer
Cancer prevention has always been a top objective, but the promise of cancer prevention remains unfulfilled. However, there are a few approaches that help in lowering the risk of colorectal cancer. These include:
- Getting screened regularly
- Maintaining a healthy body weight
- Exercising regularly
- Eating a healthy diet
- Avoiding alcohol consumption
- Smoking cessation
Recent evidences, has changed our understanding of cancer, its biology, and complex interaction of risk factors. The desired actions are always clear and simple to state, but execution always remain a formidable challenge. One can overcome this, by moving beyond the challenges and take necessary actions to reduce the global burden of cancer.
- Colorectal cancer statistics. https://www.wcrf.org/dietandcancer/cancer-trends/colorectal-cancer-statistics . Accessed on 25th August 2020.
- Haleshappa RA, Rao SA, Garg S, Kuntegowdanahalli CL, Kanakasetty GB, Dasappa L. Is Colorectal Cancer in Young (<40 Years) Different from those in the Elderly (>40 Years): Experience from a Regional Care Center. Indian J Med Paediatr Oncol. 2017;38(4):466-470. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5759066/
- Haggar FA, Boushey RP. Colorectal cancer epidemiology: incidence, mortality, survival, and risk factors. Clin Colon Rectal Surg. 2009;22(4):191-197.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2796096/
- What is colorectal cancer. https://www.cancer.org/cancer/colon-rectal-cancer/about/what-is-colorectal-cancer.html. Accessed on 25th August 2020.
- Colorectal cancer. https://medlineplus.gov/colorectalcancer.html. Accessed on 25th August 2020.
- Colorectal cancer. https://www.radiologyinfo.org/en/info.cfm?pg=colocarcinoma. Accessed on 25th August 2020.
- American cancer society guideline for colorectal cancer screening. https://www.cancer.org/cancer/colon-rectal-cancer/detection-diagnosis-staging/acs-recommendations.html#:~:text=The%20ACS%20recommends%20that%20people,rectum%20(a%20visual%20exam). Accessed on 25th August 2020.