Rectal cancer : aspects on preoperative radiation, surgery and local recurrence

Abstract

Rectal cancer is one of the most common malignant diseases in Sweden and is diagnosed in about 1.900 patients annually. Potentially curative surgery can be performed in 60-70% of these patients. Local recurrence is a major problem after surgery for rectal cancer. In Sweden, the local recurrence rate after potentially curative surgery has been 25-40% in different reports. Adjuvant radiation has been tried to improve local control.

The Stockholm Rectal Cancer Study Group have performed two randomised trials on high dose, short term, preoperative radiotherapy in operable rectal adenocarcinoma. In the first trial a twofield radiation technique to a relatively large target volume was used. The second trial used a four-field technique to the pelvis only. The trials included 1.406 patients during 1980-1993. Preoperative radiation significantly reduced the local recurrence rate in both trials. In the second trial the overall survival was improved in curatively operated patients. There was an increased postoperative mortality in irradiated patients. This increased mortality was statistically significant in the first but not in the second trial.

This thesis was based on the patients included in the Stockholm Trials and had the following aims: To assess if patient outcome is related to the operative method, hospital or surgeon. To review the causes of postoperative death and to analyse factors putatively associated with an increased risk for postoperative mortality. To assess possible late radiation complications. To analyse if preoperative radiotherapy alters the clinical course in patients with local recurrence.

It is concluded that the operative method, i.e. abdominoperineal resection or anterior resection, has no significant influence on patient outcome. The effects of preoperative radiotherapy are similar with both types of operations. Patient outcome after surgery is related to the individual surgeon. The proportional reduction in local recurrence rate after preoperative radiotherapy may be similar for most institutions and surgeons, but the absolute reduction is probably small when the local failure rate after surgery alone is low. Symptomatic cardiovascular disease, old age and distant metastases are independent risk factors for postoperative death. In patients with such risk factors, the addition of radiation may further increase that risk. There are also late adverse effects, such as venous thromboembolism, fractures and fistulas after high dose, short term, preoperative radiation in rectal cancer. The clinical course in patients with local recurrence is similar irrespective of whether the patient has received radiotherapy before the primary operation.

In summary, the risk of local recurrence and the risk of early and late adverse effects of the radiation should be considered in all rectal cancer patients on an individual basis, before a decision is taken to recommend preoperative radiotherapy.