Radiation Prior to Surgery for Rectal Cancer

Richard Whittington, MD
Last Modified: November 1, 2001

Dear OncoLink "Ask the Experts,"
I have recently been diagnosed with rectal cancer. I was told that chemotherapy and radiation was required before surgery. The mass is approximately 10cm. Frankly I would rather have surgery first. I would appreciate your thoughts on this matter.

Richard Whittington, MD, Associate Professor of Radiation Oncology at the University of Pennsylvania School of Medicine, responds:

Radiation given before the surgery is better tolerated because the tissues that are going to be removed with surgery are still in place and they push the normal tissues out of the way. This way there is less radiation to normal tissue, which is good. If radiation is given after the surgery, the small intestine will fall into the area where the tumor was located and it may get unnecessary radiation. An additional problem is that some people may have scarring of the bowels and there is an increased risk of intestinal blockage when radiation is delivered after the surgery.

Another benefit of pre-operative treatment is that radiation may be able to change the surgical approach in those patients that would normally require a permanent colostomy. If the tumor can be shrunk with radiation and chemotherapy, it may be possible to avoid a permanent colostomy. Some patients may still need a temporary colostomy after pre-operative chemo-radiation because it slows the healing and is usually closed 4 to 6 months after surgery.

The down side to treating all patients with pre-operative radiation is that some will get treated with radiation unnecessarily. Because the tests used to evaluate the extent of the tumor (CT, ultrasound, MRI, etc.) are not perfect, some patients may get radiation who probably could have been treated with surgery only. This is the major reason post-op treatment may be favored , unless it is clear from the physical examination and radiology tests that the patient will require radiation therapy even after surgery.

There are a large number of institutions that do it each way, and it would be best to talk to a doctor that does post-op treatment routinely and ask him/her what their opinion is and why.

As a general rule, patients with a tumor not through the bowel wall and no involvement of lymph nodes do not need any treatment other than surgery. If the preoperative testing suggests it has broken through the bowel wall, is stuck to other tissues, or there are enlarged lymph nodes, then that patient may need radiation and chemotherapy. The latter group is routinely treat pre-operatively with chemotherapy and radiation before surgery followed by additional chemotherapy after surgery. The former group may be recommend to have surgery and if the physicians are unpleasantly surprised by the extent of the tumor then they may get chemotherapy and radiation after surgery.