RECTAL CANCER AND OTHER GASTROINTESTINAL CANCERS
Rectal Cancer
The treatment for rectal cancer depends on the location and extent of the tumor. The goals of treatment are to cure the malignancy and to do so without a permanent colostomy. Early-stage rectal cancers may be treated either with endocavitary irradiation alone or transanal excision. Tumors that may be somewhat less favorable are often treated with a transanal excision combined with either preoperative or postoperative radiation therapy. More advanced rectal cancers require removal of part or all of the rectum. If at all possible, only part of the rectum is removed and a permanent colostomy is avoided. Often, advanced tumors require adjuvant radiation therapy combined with fluorouracil (5-FU) chemotherapy to reduce the risk of recurrent cancer in the pelvis and improve the chance of survival.
Before any treatment is started, the recommended treatment, the reasons it is recommended, the procedures to be carried out, the expected or possible side effects or complications, and the expected benefits are all explained to the patient and family. The patient must give permission for treatment, based on this knowledge ("informed consent"), before treatment is given.
Radiation therapy is more effective and better tolerated if given before the operation. Treatments usually are given once a day, 5 days a week, over approximately 5 to 6 weeks. The treatments tend to be well tolerated, with side effects such as minimal diarrhea and/or burning with urination. The surgery in these situations generally takes place approximately a month after completion of external-beam radiation therapy. If at the time of the operation it appears that there may be areas at high risk for tumor remaining, it is possible to perform intraoperative brachytherapy where catheters are placed into the tumor bed and then afterloaded with radioactive isotopes. This provides a boost dose of radiation to the tumor bed without exceeding the radiation tolerance of the small intestine, thus reducing the risk of a complication such as a bowel obstruction.
The chance of cure is approximately 90% for early-stage rectal cancers, 60-70% for moderately advanced rectal cancers, and approximately 20% for advanced, unresectable rectal cancers that are fixed to structures that are not removable, such as the side walls of the pelvis or the upper part of the sacrum.
