PHOENIX—Five-year results of a pilot study at the Ochsner Clinic, New Orleans, suggests that a 4-day course of brachytherapy may be just as effective as a 6-week course of external beam radiation therapy in breast cancer patients who have undergone breast-conserving surgery.
Women who live a good distance from a radiation facility or who have no means of transportation often wish to avoid lengthy external beam radiation therapy that can involve as many as 30 trips to the facility.
In this feasibility study of 50 women with 51 breast cancers (median age, 67), 63% lived more than 30 minutes from the radiation oncology facility, Robert R. Kuske, MD, said at the 40th annual meeting of the American Society for Therapeutic Radiology and Oncology (ASTRO). “Half of the patients on this trial depended upon a friend or family member for transportation,” he said, “and two patients had no transportation.”
All the study patients had a wide local excision, axillary dissection for invasive cancers, and either low-dose rate or high-dose rate brachytherapy, in alternating blocks of 10 patients. Low-dose rate patients received 45 Gy in approximately 4 inpatient days, and high-dose rate patients received 32 Gy in eight fractions separated by at least 6 hours over 4 outpatient days.
Tumors had to be less than 4 cm in size with negative margins and 0 to 3 positive nodes. Two-thirds of patients were T1N0; five had pure DCIS; nine were node positive. Only four had T2 disease.
“All of the study patients completed the prescribed therapy, and systemic therapy was unaffected by the brachytherapy,” Dr. Kuske said. “In fact,” he added, “systemic therapy started earlier than it would have with 6 weeks of external beam radiation therapy given first.”
Toxicity was the main endpoint of this phase II trial, with 46% of patients having any complication, 26% grade 2-3 toxicity, and only two patients grade 3 toxicity. There was no difference in complication rates between those treated with high-dose rate or low-dose rate brachytherapy.
Fat Necrosis Linked to Smoking
The most common complications were fat necrosis, infection, and mild telan-giectasia, Dr. Kuske said. Multivariant analysis showed an independent association between these complications and smoking, volume of the excision specimen, and volume of the prescription isodose curves. “Patients who were smokers had a 47% incidence of fat necrosis with a significant P value,” he said.
Cosmesis was judged to be 70% good to excellent and 30% fair to poor. Dr. Kuske noted that there was no difference in cosmesis in a blinded matched-pair analysis between brachytherapy and external beam patients treated at Ochsner.
With a median follow-up of 5½ years, “there has been not one breast recurrence in this trial,” Dr. Kuske said. There have been three regional lymphatic recur-
rences: one in the infraclavicular area “that would have been outside of a standard tangential field,” he said; one Rotter’s node recurrence; and one internal mammary node recurrence. Four patients have developed distant metastases.
Although local tumor control has been “excellent” so far, Dr. Kuske noted that remote recurrences, although rare, tend to occur between 5 and 10 years post-treatment, so “we have to watch these patients for remote relapses as well as local relapses over the next 5 years.”
Dr. Kuske said that an ongoing phase II study, RTOG 95-17, is addressing the “reproducibility of this implant program outside the Ochsner Clinic.” He pointed out that the ongoing trial is using more stringent selection criteria than the pilot study, so as to select favorable prognosis patients.
