Postoperative local radiotherapy in rectal cancer: treatment results with limited radiation fields

Postoperative low pelvic radiotherapy and chemotherapy for stage II and III rectal cancer

OBJECTIVES

To evaluate whether postoperative low pelvic radiotherapy (RT) combined with chemotherapy is an appropriate treatment for stage II and III rectal cancer.

METHODS

Between November 1997 and May 2006, 104 patients with stage II and III rectal cancer underwent surgery as the primary treatment followed by postoperative RT combined with chemotherapy in our institute and were reviewed retrospectively. Sixty-nine patients received low pelvic RT only (upper margin at 1 cm above the low end of the sacroiliac joint; median dose 54 Gy) (low pelvic RT group) and the other 35 patients received whole pelvic RT (upper margin at the mid L5; median dose 43.2 Gy) and subsequently received a boost to the low pelvis (total median dose 54 Gy) (whole pelvic RT group).

RESULTS

The 5-year overall survival rate, local control rate, and distant metastasis-free rate were 72% versus 63%, 86% versus 84%, and 66% versus 62% for low pelvic versus whole pelvic RT group. There were no statistical differences in these 2 groups. Two patients (2.9%) of the low pelvic RT group and 2 patients (5.7%) of the whole pelvic RT group developed upper pelvis relapse, which was out of the low pelvic field. The incidence of Grade 3 to 5 small bowel late complications of the low pelvic RT group was significantly less than that of the whole pelvic RT group (4.3% vs. 20%) (P=0.029).

CONCLUSIONS

Low pelvic RT significantly reduces small bowel late complications and does not compromise the overall survival rate, local control rate, and distant metastasis-free rate.

The prognostic significance of p53 expression for survival and local control in rectal carcinoma treated with surgery and postoperative radiotherapy

PURPOSE

To investigate whether p53 immunoreactivity is a prognostic factor for survival and pelvic control in rectal carcinoma treated with surgery and postoperative radiotherapy.

METHODS AND MATERIALS

From 1981 through 1989, 146 patients with rectal carcinoma received postoperative radiotherapy and were followed for at least 5 years or until death. The specimens of 123 of these 146 patients could be retrieved and examined immunohistochemically for p53 expression. The prognostic value for survival and pelvic control of p53 expression and other patient and treatment factors was examined by univariate and multivariate analyses.

RESULTS

p53 expression has no prognostic significance for overall survival in this group of 123 patients. The only prognostic factor for survival in this material is tumor stage (p < 0.01). The actuarial pelvic recurrence rates of p53- and p53+ cases are different in favor of the p53- ones. In the univariate analysis this difference is significant (p = 0.05). However, in the multivariate analysis the influence of p53 expression, additional to stage, becomes nonsignificant (p = 0.10). This indicates that p53 expression is not a strong independent prognostic factor for pelvic recurrence. In the multivariate analysis stage turns out to be the only predictor of pelvic recurrence (p = 0.03). When only recurrences inside the radiation field are considered, there is no difference between p53+ and p53-cases.

CONCLUSION

Based on this material, we have found no convincing evidence that p53 expression is an important predictor of survival or local control in rectal cancer treated with surgery and postoperative radiotherapy. We have found no evidence that possible differences in radiosensitivity between p53+ and p53- tumors have clinical significance for this group of patients.

Adjuvant postoperative radiotherapy in rectal cancer: 148 cases treated at Florence University with 8 years median follow-up

BACKGROUND AND PURPOSE

To analyse the outcome, the treatment related side effects, the prognostic significance of clinical parameters in a group of patients with rectal cancer receiving postoperative radiotherapy after radical resection.

MATERIALS AND METHODS

From 1980 to 1990 148 consecutive patients with rectal carcinoma stage B2-B3 or C1-C2-C3 were treated with postoperative radiotherapy after radical surgery. All patients received 50 Gy in 25 sessions in 5 weeks. In 42 a "flash' dose of 5 Gy was also given within 24 h before surgery. Median follow up was 8.1 years.

RESULTS

At 5 years the overall survival was 54%, the determined (cancer specific) survival 61%, the local recurrence-free survival 88%. The influence of stage, histotype, distance from anal margin, type of surgery, number of involved nodes and flash dose were analysed. Overall and determined survival and distant metastasis rate were significantly influenced (P < 0.005) by the pathological stage. Patients with more than 3 involved nodes presented a significantly lower determined survival (P < 0.001) and a higher distant relapse rate (P < 0.005) than those with 3 or less involved nodes. A higher determined survival (P < 0.01) was also found in patients receiving the preoperative "flash'; this group was however unbalanced in respect to the relative number of cases with 3 or less involved nodes. The incidence of major side effects requiring surgery or hospitalization for medical treatment was 35% before 1985 and 12% thereafter. The systematic use of small bowel visualization during simulation and the discontinuation of the flash dose were the main modifications introduced in the second period. As a consequence of the small bowel visualization the size of lateral fields was slightly reduced and some patients were excluded from the treatment.

CONCLUSIONS

Value of postoperative radiotherapy to decrease the incidence of local recurrence was confirmed in this retrospective study; the incidence of side effects was however considerable and did not support the addition of chemotherapy as advised by the NIH consensus meeting. Our policy was therefore moved to preoperative irradiation whose combination with chemotherapy was recently reported to be better tolerated and highly effective.