Colon Cancer Treatment

Colorectal cancer has a wide range of treatments that can be used alone or in combination to give the best outcome for your specific cancer. That’s why careful diagnosis and staging is so important.

As part of a research medical center, physicians at the Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine in St. Louis have access to a wide range of clinical trials to test new therapies as they emerge. Many of our physicians are principal investigators in these trials, which cover medical, surgical and radiation therapies. Discuss with your physician how your cancer might benefit from clinical trials.

Because many of our patients come from over 100 miles away, when you meet with a surgeon, you often see the radiation and medical oncologists at the same visit and get imaging for staging.

Medical Treatments for Colon Cancer


Chemotherapy involves the administration of drugs, either orally or intravenously, to kill cancer cells. Recently, several new drugs have increased the options for physicians treating patients with colon and rectal cancers. Therapy that falls under medical treatment has a wide range of approaches, including timing of treatment.

Neoadjuvant chemotherapy: Sometimes a rectal tumor is too large to avoid damaging the sphincter muscle with surgery. If the tumor size was marginal for excising without harming delicate structures, chemotherapy and/or radiation before surgery may make it shrink to protect those structures. In those cases, neoadjuvant, or preliminary, chemotherapy and/or radiation given before surgery can shrink the tumor and make it easier to remove. Using chemotherapy and radiation before surgery also helps prevent recurrence in the pelvis.

Adjuvant chemotherapy: Most chemotherapy is given after surgery. Data going back almost 15 years show that chemotherapy after surgery improves the survival rate of patients with colon and rectal cancer by about 30 percent. For patients with cancer that has spread (metastatic), chemotherapy can improve survival and quality of life. Chemotherapy and radiation may both be given after surgery. When patients receive standard therapy for their tumor, they may also be advised to add a clinical trial drug to be given at the same time to improve survival rates.

Intravenous forms of treatment may require the placement of a Port-a-Cath. The catheter and port are inserted under the skin into the internal jugular vein right around the collar bone in a patient who will be getting multiple chemotherapy treatments. This allows treatments to be given without damaging the veins or increasing the risk of the medicine leaking out of the vein. It can also be used to draw blood samples to monitor therapy. The port into the catheter lies just under the skin and isn’t noticeable from the outside. When the nurse wants to give chemotherapy, the skin is cleaned and the needle is inserted through the skin into the port to deliver the medicine. It stays in place for the duration of treatment.


Biological therapy, sometimes called immunotherapy, is a treatment that uses materials made by the patient’s own body or in a laboratory to stimulate the immune system to fight disease. Siteman researchers are now participating in clinical trials to test this form of therapy.


The lower gastrointestinal physician team treats more than 650 patients yearly with colon, rectal and anal cancers. To treat the conditions effectively, specific diagnosis and staging are of the utmost importance. Depending on the biology and genetics of the tumor, patients will often be recommended to have neoadjuvant radiation and/or chemotherapy before surgery. Determining the need for neoadjuvant treatment involves careful treatment planning and incorporating location, stage, depth of the cancer in the colon wall and whether lymph nodes are involved. Pelvic MRI gives surgeons the most information, revealing most clearly the circumferential margins of the tumor and how close it comes to outer edges of surgery without long-term consequences. Learn more about surgery at the Siteman Cancer Center.

Colon surgery

More than 60 percent of colorectal surgeons’ patients have laparoscopic surgery, which has been found to be as safe and effective as standard incisional open surgery for cancer confined to the colon.

Preventive colon surgery: Patients with familial adenomatous polyposis (FAP) can have hundreds or thousands of colon polyps before age 18-22, so the best way to prevent the cancer is to remove the colon.

Rectal/anal surgery

Ten to 15 years ago, tumors in the lower third of the rectum usually required taking out the anal sphincter muscle and giving the patient a colostomy, a drainage site routed to the abdomen where a bag collected solid waste. Now surgeons understand that any cancer not directly involving the sphincter muscle or pelvic floor, and with enough distance between it and normal tissue to achieve a clear margin, makes it possible to preserve normal bowel function.

Careful treatment planning and analysis of the tumor gives the surgeon important information about whether a short course of radiation for five days, followed by immediate surgery, would be the treatment of choice. The current standard of care is a long course of radiation and chemotherapy for five weeks with an eight week recovery period, followed by surgery. For the appropriate candidates, both approaches show a decrease in local recurrence and no difference in long-term survival.

Another option is to start with chemotherapy alone. Not all tumors respond to radiation or the combination of radiation and chemotherapy. There are many different treatment regimens for patients with rectal cancer to individualize their care. The majority of rectal cancer patients are eligible for clinical trials.

Transanal endoscopic microsurgical (TEM) excision is a surgery only offered at Siteman that allows for the removal of benign polyps and early cancers from the anal area. The approach is minimally invasive and allows better visualization and access to nearby lesions than traditional methods. It is also being used in appropriate patients to remove more advanced cancers in conjunction with radiation therapy.

Treating rectal cancer is a delicate balance between getting rid of the cancer and optimizing bowel function. That requires doctors who collaborate as ours do. However, despite all the latest clinical trials, imaging and treatment modalities, a small percentage of patients will still need colostomies and will have the support of experienced enterostomal therapists to help them learn to manage them.

Radiation Therapy

Each patient’s case is presented at a multidisciplinary conference to personalize his or her treatment, including surgery, radiation oncology, chemotherapy and pathology to take into account specific tumor characteristics. Radiation oncology has active trials for minimizing the duration and amount of radiation a patient receives to reduce long-term side effects. No one should be over- or under-treated. Siteman is a leader in using shorter radiation durations than the national average with the same outcomes.

Radiation’s role in the treatment of colorectal cancer is primarily to:

  1. Treat rectal cancer that has a high chance of recurring with surgery alone.
  2. Treat a cancer that has spread from the rectum or colon to other organs, like the liver.

External beam radiation: Ninety-five percent of radiation treatment at Siteman is external beam from outside the body. Siteman fine-tunes the radiation planning with intensity modulated therapy, using a large-bore CT simulator for 3D or full positioning to precisely target therapy. Our team was the first in the world to have the ability to do external radiation with MRI guidance, and the first to treat patients with that technology.

MR-guided adaptive radiation therapy:  Siteman is the only center in the world performing MR-guided adaptive radiation therapy.  By using an MRI to guide the radiation therapy and assessing the position of critical structures such as the small bowel and bladder, Siteman radiation oncologists can adjust, or adapt, the radiation to the patient every day.  This technique has been especially useful in difficult cases of colorectal cancer, where the disease has spread near adjoining tissues and/or to lymph nodes in the abdomen.