The three main modalities, or types, of treatments used for colorectal cancer treatment are surgery, radiation therapy and chemotherapy. Many patients will receive two or even three of these treatments together. Several types of operations are used for treating people with colon cancer: polypectomy, or simple removal of a polyp usually through a colonoscope; local excision, which removes a superficial cancer through the inner layers of the nearby non-cancerous colon tissue; a segmental resection, which removes about half to a third of the colon and nearby lymph nodes; and a diverting colostomy, which does not remove the cancer but bypasses blockage of the bowel by diverting feces to a colostomy. Diverting colostomy is often used for very, very advanced cancers, or for people who for other medical reasons are unable to tolerate removal of the cancer.

The operations used for treating people with rectal cancer include polypectomy (removing the polyp) and transanal local excision and transanal local full thickness resection, two procedures that are done, as the name implies, using instruments operated through the anus. Other operations are a low interior resection and abdominoperineal resection, which removes a greater amount of tissue. It's important to remember that a colostomy is needed after the abdominoperineal resection or after a pelvic exenteration. The pelvic exenteration is the most extensive operation that is used for treating rectal cancer. It removes not only a section of the rectum but may also remove other organs and tissues to which the rectal cancer has spread, such as perhaps the bladder or the genital organs in women, like the uterus.

Again, a diverting colostomy is used for people with very, very advanced cancer that's blocking the flow of feces. This operation will restore fecal flow out to a colostomy but not remove the cancer.

Other surgical procedures that are done for rectal or colon cancer include removal or ablation of metastases. Ablation means destruction without removal. There are several techniques for ablation of metastases that include using microwaves or cryotherapy (meaning, using very cold temperatures) to kill the cancer cells. These are particularly effective in people with a small number of liver metastases. In some cases, removing or destroying some of these liver metastases can help the patients live much longer. And it can even be helpful in some cases for a person with a completely receptible, or removable, colorectal cancer. And only a couple of liver metastases that can be completely removed can be cured.

Radiation therapy is also used for treating people with colorectal cancer. The type of radiation most commonly used is external beam radiation therapy. This is very much like getting a diagnostic x-ray while radiation is beamed from the source outside the body at the cancer.

Brachytherapy is a technique in which radioactive pellets of material are inserted within the cancer. But this is very rarely used with colon cancer. It is sometimes used if the surgeon is unable to remove all of the cancer and cancer remains behind after surgery.

Something that's under study is a technique called intraoperative high dose rate brachytherapy, where brachytherapy is used during surgery. A radioactive source is placed right next to the cancer while the patient's colon is exposed during surgery, and then the source is removed so that it's not there after surgery. For rectal cancer, external beam radiation therapy is also used.

There's another type of radiation that is particularly designed for rectal cancer called endocavitary radiation therapy. In this case, the radiation is aimed through the anus at the rectum cancer. Brachytherapy is only used occasionally in rectal cancer, as in colon cancer.

The side effects of radiation therapy include mild skin irritation, nausea, diarrhea, rectal irritation, bladder irritation and fatigue.

Patients with colon cancer and rectal cancer often receive chemotherapy. This chemotherapy can be used in two ways: as adjuvant, or additional, therapy before or after surgery; or as palliative chemotherapy to relieve or delay symptoms for people with advanced or a current colorectal cancer.

Fluorouracil (5-FU) is a drug most commonly used for people with colorectal cancer. And it's often combined with one of two other drugs, leucovorin or levamisol. They can usually be given by intravenous injection over a short period of time, such as five minutes. They're also sometimes given by continuous IV infusion very slowly by a battery-operated pump. Or it can be given directly into the hepatic artery, which is the artery that leads directly into the liver. This is sometimes used for people with liver metastases from a colorectal cancer. This approach allows a more concentrated dose of the drug to be given directly into the liver.

Another drug called irinotecan (CPT-11) is used for people whose cancer is not responding to 5-FU. Sometimes this drug may be given as first-line therapy before 5-FU is tried.

The temporary side effects of chemotherapy include nausea, vomiting, loss of appetite, temporary loss of hair, hand and foot rashes, mouth sores, decreased resistance to infections, fatigue and increased tendency to bleeding or bruising.

In considering colorectal cancer treatment options, it's best to consider them by stage, because people with different stages of colon and rectal cancer will benefit from different treatments.

For people with stage zero colon cancer, the earlier stage, the usual treatment is polypectomy (local excision). Or, if the tumor is large but still very superficial, segmental resection may be opted for. For stage one, the standard treatment is segmental resection. For stage two, segmental resection is standard as well. The patients and doctors may also consider chemotherapy, perhaps with radiation therapy, as part of a clinical trial. For stage three, again, segmental resection and chemotherapy and considering radiation therapy in addition to surgery and chemotherapy. For stage four colon cancer, segmental resection or diverting colostomy. Also, the patient may consider removal or ablation of metastases, chemotherapy and/or radiation therapy, clinical trials of immunotherapy, new chemotherapy drugs, or other new treatments. And for recurrences, remove local and distant recurrences when possible. Consider ablation of distant recurrences and consider clinical trials of new treatments.