A month of postoperative radiotherapy preceded by radiosensitizing boluses of fluorouracil(Drug information on fluorouracil) (5-FU) slashed the recurrence rate and markedly improved survival in patients with Dukes B and C rectal cancer in a study from the Norwegian Adjuvant Rectal Cancer Project Group, presented at the European Cancer Conference (ECCO-8).
"The effect is comparable to more prolonged, resource-demanding, and toxic regimens, such as the 6-month and 18-month regimens used in the United States today," said Dr. K. M. Tveit of the Norwegian Radium Hospital, Oslo.
He called the regimen "a good alternative that can be recommended in patients with a high probability of local recurrence and in institutions where the local recurrence rate with surgery alone is relatively high--more than 10%."
Subjects randomized to the experimental arm of this 144-patient trial received 23 fractions of 2 Gy with a three-field technique, starting 4 to 6 weeks after surgery. Patients were treated in the prone position with a full bladder to minimize toxicity to the bowel.
In an attempt to achieve an optimal interaction between fluorouracil and radiation, fluorouracil doses of 500 or 750 mg were administered 30 minutes before radiotherapy fractions 1, 2, 11, 12, 21, and 22.
Five-year relapse-free survival reached 64% in patients who underwent adjuvant therapy, compared with 46% in the surgery-alone patients, Dr. Tveit reported. Five-year overall survival was 64% in the adjuvant therapy group and 49% in the control group.
The incidence of local recurrences, most of which were associated with distant metastases, was only 12% in the adjuvant therapy arm vs 30% in the control group, he said.
Except for three cases of grade 3 dermatitis, adjuvant therapy was well tolerated, Dr. Tveit said, emphasizing that there was no excess incidence of small bowel obstruction in the adjuvant therapy group.