Colon Cancer:
Colon cancer remains a very common cancer in both men and women, and is the 3rd leading cause of cancer deaths.
The Risk Factors include:
-Age: starts increasing after age 40, mainly presents in the
-Family History: increases by 8-17 % when the number of 1st degree relatives with colon cancer goes from 1 to 2.
-Other inherited genetic disorders: hereditary non-polyposis Colon cancer (HNPCC), and Familial Adenomatous Polyposis (FAP), which presents with extensive polyps throughout the colon, and carries a 100% risk of colon cancer. This requires a preventive total colectomy.
-Personal history of Ulcerative Colitis or Crohn’s disease. Risk increases with each decade.
-Geography: Incidence is higher in industrialized countries. This is likely related to
-Diet: increased fat content has been linked to increased risk; increased fiber/ vegetable intake is linked to decreased risk.
Screening and Early Detection: Saves lives
If the cancer is detected at an early Stage 1, the 5-year survival is more than 90%.
If it has penetrated through the bowel wall (Stage 2) or to the regional lymph nodes (Stage 3), the 5-year survival drops to 60%. If there is distant spread (Stage 4), it drops to less than 10%. Cancer develops in the internal lining, and often causes intermittent bleeding. This doesn’t look like blood when it comes out because it is chemically altered. There are special cards, which can detect this hidden, or “occult” blood.
Screening: should begin at age 50; earlier if there are risk factors. This should include
-Stool testing for hidden blood: samples are collected either by a finger examination, or by giving the cards to patients to collect at home.
-Visualization of the inside of the colon by insertion of a tube with a light and camera. This requires a bowel cleansing, so the lining can be properly visualized. The benefit of this examination is that any polyp can be removed. Polyps can be pre-cancerous, hence the survival benefit that is accrued by colonoscopy screenings.
-Barium enemas, which can also examine the inside of the colon, but then requires a follow up colonoscopy to biopsy and remove polyps.
Staging and Treatment:
Once the cancer is detected, a series of examinations are started to determine the most appropriate course of action. Initial staging will require a CT scan of the abdomen/ Pelvis and Chest, to make sure that the disease has not spread to the liver and lungs, and a CEA level. This CEA level is a measure of the amount a cancer protein is shedding, and is called a tumor marker. Not all colon cancers will over produce CEA, but if it does, it is a measure of treatment response and recurrence detection.
Curative Treatment: consists of initial surgical resections of the involved piece of colon. This also allows a good look around the abdominal cavity to ensure that there is no hidden disease that was not detected by the CT scan. Pathological examination of the removed tissue tells us the extent of the cancer, involvement of the lymph nodes and the completeness of the resection, i.e. “clean margins”. This determines whether there is need for post operative, or “adjuvant” chemotherapy. In locally advanced disease, or with lymph node involvement, the risk of relapse increases. This can be reduced by chemotherapy.
The prescribed chemotherapy cocktails have changed over the years, and will continue to change with the discovery of newer, and more effective drugs. The backbone of the treatment still remains an infusion of 5 Fluorouracil over 48 hours, with Oxaliplatin, and Leukovorin (FOLFOX). This is repeated every 14 days, for 12 treatments.
Non-curative treatment is undertaken when the disease has spread outside the colon and immediate vicinity. This may involve surgery, if the primary tumor is causing bleeding, or obstruction. If not, the mainstay of treatment is combination chemotherapy. The duration is open ended. The combination of first choice depends on whether this is re-treatment, or freshly diagnosed disease, and can be a choice between various combinations including FOLFOX, FOLFIRI (substituting Irinotecan for Oxaliplatin), Capecitabine (an oral formulation of 5 FU), and additional drugs which interfere with new blood vessel formation (anti-angiogenic) drugs e.g. Avastin, or drugs which work on mutations of growth receptors (cetuximab) e.g. Erbitux. As new trials are continued on newly developed drugs, these recommendations will change. Treatment is continued till as long as there is a response, and the combinations are used in a serial fashion, till current choices are exhausted, or the patient’s condition deteriorates, and cannot undergo further therapy. This interval can last from anywhere between a few months to a few years, depending on how the situation evolves.
Role of Radiation therapy is limited to areas of concern e.g. spread to the brain, painful bony disease, or, in the adjuvant setting, when the surgical resection required dissection off from the abdominal wall.
Other Palliative measures will include Pain Management and Nutritional support.