Colorectal Cancer is common, and there is a lifetime risk of developing colorectal cancer of approximately 1 in 22 people.
This is a cancer that starts in the colon (large intestine) or rectum (the last part of the colon before the anus). Colon cancer is generally not symptomatic until more advanced stages, or when causing an obstruction. This is why screening tests for colorectal cancer are so important. Screening involves a physical exam, including a rectal exam, and tests ranging from testing stools for occult blood or cancer cells, to imaging studies like a barium enema or CT colonography. But the “gold standard” colorectal cancer screening test is a colonoscopy. If a tumor is found, or suspected from other screening tests, a colonoscopy is still required.
At colonoscopy the entire colon and rectum mucosa can be viewed and biopsied. Pre-cancerous polyps can be removed if they are not too large. The location of the cancer is identified by surrounding landmarks if it is near the junction with the small intestine or near the anus. And it is usually marked with permanent ink so that it can be found at surgery, since the inside of the colon is not visible at the time of surgical resection.
When a colon mass is found at colonoscopy, and cannot be resected like a polyp, at colonoscopy, then the patient is referred for surgical resection. This means that the section of the colon that contains the mass is removed. The same resection is done whether the mass is cancer (by biopsy) or just adenomatous (pre-cancer). This is because when a pre-cancerous polyp (or mass) is too large to be removed at colonoscopy, then there is risk that a part of the polyp not biopsied contains cancer. The amount of colon that needs to be resected depends on the location of the mass, as the resection required is determined by the location of the mass relative to the different blood supplies to the colon. It usually ends up being around 12 inches.
I perform the vast majority of colon resections laparoscopically. This means that the surgery is done through multiple small holes in the abdomen using a camera and long instruments to do all the work on the inside. Depending on the part of the colon being removed, one of the small incisions is enlarged to the degree necessary to remove the specimen. This is usually less than 2 inches. Patients generally come to the hospital the morning of surgery, and stay, on average, 3 days after surgery. Patients are not sent home before they feel ready to go home, and have demonstrated some bowel function with the passage of either flatus or stool. The diet is advanced during that stay, and when patients go home, they can eat normal foods. When patients are discharged, they are offered a prescription for pain medication, but many do not feel they need it. There is some discomfort, and strenuous activity and lifting should be limited for 6 weeks. The incisions themselves are closed with absorbable sutures under the skin, and a glue-like dressing on them. It is ok to shower the day after surgery, but not to submerge for 10 days. Patients return to the office for follow-up at 2 weeks after surgery.
Rectal cancer is managed in a similar way, but it can be a more difficult, and/or more involved surgery if the tumor is low in the rectum. That is why it is very important to know the exact distance (in centimeters) from the anus for any tumors found to be in the distal sigmoid or rectum on colonoscopy. If this information is not documented at the time of the colonoscopy, I may perform another sigmoidoscopy to determine that information. Many times for rectal tumors you may need to have an endo-rectal ultrasound or MRI to obtain more staging information before surgery, as in many cases, rectal cancers are best treated by having chemotherapy and radiation therapy before surgery.
Whether a patient will require chemotherapy for colon cancer, depends on the staging. The staging of colon cancer is based on three factors, similar to the staging of other cancers. T.N.M. The T (Tumor) is for the depth of invasion through the wall of the colon. This can generally only be determined after the specimen is surgically removed. The N (Nodes) is for the number of lymph nodes in involved with cancer. This is also determined by the pathologist by reviewing the surgical specimen. The M (Metastasis) is for whether there is any distant spread of the cancer, usually to the liver, but can also go to the lungs and brain. This is generally evaluated either before of after surgery with CT scans. In general (but not always), if there are lymph nodes involved, or distant disease, then chemotherapy will be recommended. It generally takes at least 3 business days for the pathology results to come back.
Probably the most common concern patients have before colon surgery is whether they will have to have a colostomy (an opening on the abdomen where stool flows into a bag). This is not common. A colostomy is generally required only for low rectal cancers, obstructing colon cancers and when there are complications after colon surgery. Thankfully this is a rare occurrence.
More information about staging and treatment options can be found at the American Cancer Society website: http://www.cancer.org/cancer/colonandrectumcancer/index