Colon Cancer

Overview

The colon is responsible for converting waste into feces to be expelled from the body. Food will travel to the colon in process that takes approximately 3-8 hours after consumption. During this time nutrients will be assimilated into the body, what is left is waste.

Colon cancer is the 3rd most common cancer found in both men and women. In the west approximately 105,000 cases are diagnosed every year, specifically in the United States. The chances of colon cancer increases in individuals aged over 50. Most cases of colon cancer begin as small, noncancerous (benign) clumps of cells called adenomatous polyps. Over time some of these polyps become colon cancers. In Thailand, this cancer is becoming more prevalent in both men and women.

Groups with high risk factors are individuals with a family history of colon cancer, polyps in the colon area, congenital conditions, inflammatory bowel disease, and Crohn’s disease. People with these factors should seek medical diagnosis to detect cancer early on.

Individuals with a family history of this condition such as father, mother, and siblings are at 2/3 higher risk than the average person. However, it is found that 80% of patients diagnosed with colorectal cancer did not show signs of risk factors.

Research indicates that lifestyle habits can be a major contributor to colon cancer. These may include a high diet of fatty and red meats with little to no fruit and vegetables. Other factors include high energy foods, lack of exercise, and obesity. Smoking and alcohol consumption can also contribute to colon cancer.

Stages

Stage 0 (pre-cancer) – Cancer is found on outer wall of colon
Stage I – Cancer is found in the 2nd and 3rd layer of the colon wall. However, it is not found in the outer wall. This stage is also referred to as Duke’s A.
Stage II- Cancer has spread to the colon wall but not to the lymph nodes. This staged is also referred to as Duke’s B
Stage III – Cancer has spread to colon wall and lymph nodes but has not spread to other organs. This stage is also called Duke’s C.
Stage IV – Cancer has spread to other organs such as liver and lungs. This stage is also called Duke’s D.

Symptoms

May include bleeding through the rectum, blood in feces, changes in feces (shape and size), and stomach pain. However, these symptoms may not be obvious at early stages.

Symptoms of colon cancer include: feces accompanied by blood, constipation without cause, chances in feces size and shape, pain when flexing to poo, persistent abdominal discomfort, weakness or fatigue, and unexplained weight loss.

Diagnosis

Patients will receive diagnosis to determine stage and spread of cancer. This can be done with lower endoscopy, double contrast barium enema, blood tests to determine level of carcinoembryonic antigen (CEA), chest x-ray, CT scan of abdomen. To determine spread of cancer CT scans, MRI, and EUS may be used.

Surgery

Surgical treatment will be in accordance to location of cancer

Rt. Extended Hemicolectomy
Transverse colon, Transverse colectomy
Lt. Hemicolectomy
Sigmoidectomy
Sigmoidectomy with Hartman’s pouch

In cases where the cancer is located in an area with large bone, it may provide difficulties for the surgeon to gain access; in this case an AP resection may be required.

For patients with a tumor that is too large to be surgically removed, radiotherapy and chemotherapy will be used initially in a process referred to as ‘down staging’ to reduce the tumor size before surgical treatment can begin.

Patients in stage 0 and 1 will only require surgery
Patients in stages 2 and 3 are at risk of recurrence as such radiotherapy and chemotherapy will be utilized before and after the surgery

Although most patients will be able to successfully remove the entire tumor the recurrence rate is at 50-60%.

Chemotherapy to Reduce Chance of Recurrence

Patients in the second stage who experience intestinal obstruction or radically abnormal cancer cells (from biopsy) are at risk of recurrence and will be treated with fluorouracil (5-FU) and leucovorin (LV). Both of which are medication that is administered over a period of 6 months. Patients in the second stage will be closely monitored and may not necessarily require chemotherapy. Patients in the 3rd stage will receive fluorouracil and leucovorin for 6 months. This method provides a higher survival rate compared to if surgery was the only method used.

Patients in the 4th stage will be treated by surgical removal of tumor, as well as radiotherapy and/or chemotherapy.

During surgery, some patients may require management to prevent the cancer spreading to nearby organs such as the liver or ovaries. To prevent spread of cancer the following medication is effective: fluorouracil, leucovorin, irinotecan (CPT-11 or Camptosar), or oxaliplatin (Eloxitin). Adding irinotecan and oxaliplatin to fluorouracil and leucovorin can help to improve effectiveness of treatment.

Author

Dr. Wutthi Sumetchotimaytha
Surgical Oncologist