Although colon cancer and rectal cancer share many features, there are important differences between these two diseases including, especially, the tendency for rectal cancer — but not colon cancer — to recur locally. Local recurrence of rectal cancer is common after standard surgery and is often catastrophic. It is difficult to cure, and the associated symptoms are debilitating. Accordingly, preventing local recurrence is one of the main treatment goals with rectal cancer.
The prognosis (outlook) with rectal cancer is clearly related to the degree of penetration of the tumor through the bowel wall and the presence or absence of lymph node involvement. These two characteristics form the basis for all staging systems developed for this disease.
The standard surgical procedure is called total mesorectal excision (TME) . Preoperative chemoradiotherapy has been found to reduce the risk of local recurrence and to cause fewer long-term toxic effects than if the chemoradiotherapy is given postoperatively. Broadly, at five years, the overall survival among patients with locally advanced rectal cancer, irrespective of whether they have had preoperative or postoperative chemoradiotherapy, is about 75%.
The treatment options for rectal cancer depend on several factors and the decision for each case is often an individualized decision for that particular patient. Certain guidelines are quite clear and if the patient falls within those criteria, the treatment is standard.
For Example Stomach Cancer
In case of early rectal cancer where the tumor is confined to the wall of the rectum and does not extend to the surrounding fat or mesorectum with no lymph node involvement, the treatment is surgery. Often this surgery will be performed laparoscopically or occassionally even through the anal canal (Transanal endoscopic surgery).
In cases where the carcinoma is very close to the anal sphincter (the muscle controlling defecation) and/or is large in size with lymph node spread or spread into the mesorectum (the fat surrounding the rectum), the best treatment option is to go for neo-adjuvant long-course chemo-radiotherapy (which is a combination of radiotherapy for 5 weeks along with oral chemotherapy) followed by a surgery after 6 weeks of completion of radiotherapy. The advantages of performing radiation prior to surgery are:
- Increased rate of sphincter saving surgeries: This form of radiotherapy significantly reduces the bulk of the tumor and its extent of spread making a sphincter-saving surgery possible in several cases where otherwise an abdominoperineal resection with a permanent colostomy would be required.
- Decreased local recurrence rate:Giving chemoradiation prior to surgery decreases the local recurrence rate of the cancer compared to the older approach of surgery followed by radiotherapy
- Lesser long-term side-effects:Since the part being irradiated is removed later during surgery, the patient suffers very few long-term side-effects, especially with the more recent methods of delivery of radiotherapy.
The decrease in the tumor size also means that majority of these tumors can still be operated by laparoscopic techniques.
In certain circumstances a neo-adjuvant short-course radiotherapy may give an equivalent effect as a long-course radiotherapy. However, these cases have to carefully selected and individualized so as to maintain the efficacy of the treatment.
In cases where the cancer has already spread (for example to distant nodes or the liver or the lungs) but both the primary tumor and the metastatic site are operable, the surgery can still be performed with excellent outcomes. However, the surgery, chemotherapy and the radiotherapy have to be accurately timed to get the optimum outcome. In most such cases, the radiotherapy used may be short-course radiotherapy to decrease the time that the patient is off chemotherapy. Dr. Sanket Mehta regularly performs rectal cancer surgery laparoscopically. He specializes in the treatment of loco-regionally advanced and operable metastatic rectal cancer. He has performed several major synchronous resections of the rectum with liver metastases or peritoneal metastases, along with CRS and HIPEC in case of pertitoneal disease