By Kathleen Doheny
MONDAY, Sept. 22 (HealthDay News) -- A more intense but briefer course of radiation therapy is equally effective as the traditional longer course for certain breast cancer patients, Canadian researchers report.
The new findings reflect a longer term follow-up than those presented five years ago, noted Dr. Timothy Whelan, lead author and a radiation oncologist at the Juravinski Cancer Centre, McMaster University, in Hamilton, Ontario.
His team was expected to present the findings Monday at the American Society for Therapeutic Radiology and Oncology (ASTRO) meeting in Boston.
"We first presented our results five years ago, but many oncologists were reluctant to adopt this," said Whelan, referring to the briefer but more intense radiation treatments. "They were concerned about long-term effects."
In the new study, Whelan's group followed the women for 12 years, comparing the results in 1,234 women with early-stage breast cancer who had a lumpectomy and then were randomly assigned to receive standard whole breast radiation for five weeks, to women who received "accelerated" whole breast radiation for three weeks.
At the 10-year mark, cancer returned locally in 6.2 percent of those who got the briefer therapy, compared with 6.7 percent of those who got traditional therapy. Cosmetic results were similar in both groups. The researchers noted no differences between the two groups in terms of radiation-linked side effects.
In a second study, also expected to be presented Monday at the ASTRO conference, Dr. Peter Beitsch, a surgical oncologist at Medical City Dallas Hospital, Dallas, said that radiation "seed" implants work well as an alternative to standard whole breast radiation. He used a type of accelerated partial breast irradiation (APBI) that involves a radiation seed implant, called balloon brachytherapy.
After the tumor is surgically removed, the doctor inserts a small balloon into the cavity, attaches a catheter to the balloon, and delivers a high radiation dose by way of tiny radioactive seeds.
Beitsch used the Mammosite Radiation Therapy System, approved by the FDA in 2002. The manufacturer, which funded the study, wanted to conduct a post-approval study, he said.
Beitsch reported on 400 women (of more than 1,400 total) now followed up for almost four years. He found that the rate of early complications, such as pockets of accumulated fluid, were similar to those of patients receiving standard therapy. Cosmetic results were similar, too.
The researchers reported 28 breast tumor recurrences (about 2 percent). "The range of recurrences for whole breast radiation is nearly zero to 5 percent," Beitsch said, so these results are comparable.
The best candidates for the seed therapy, he said, are women age 45 years or older, with tumors of three centimeters or less and a diagnosis of ductal cancer or ductal cancer in situ (DCIS). About 40 percent of women diagnosed with breast cancer would probably be candidates, Beitsch estimated.
In a third study presented at the meeting, a form of external beam radiation therapy called proton therapy reduced the risk of cancer patients developing a secondary malignancy by twofold, compared to traditional radiation therapy using photons.
Proton therapy is a more targeted radiation that delivers less radiation to surrounding areas than does photon radiation. However, during the delivery of proton therapy, neutrons are produced and scattered, and some experts fear this scatter radiation may boost the chances of a secondary cancer.
Researchers compared 503 patients with a variety of cancers -- including brain tumors, sarcomas and prostate cancer -- who had proton therapy against 1,600 who had photon therapy. After a one year or more of follow-up, 6.4 percent of those who had proton therapy got a second cancer, compared to 12.8 percent of those who got traditional photon therapy. The median followup (half were longer, half shorter) was 7.7 years for the proton group and 6.1 years for the photon patients.