Source: DGNews  |  Posted 4 years ago

By John Gever

SAN ANTONIO, TX -- December 14, 2007 -- Initially promising results seen with accelerated hypofractionated whole-breast irradiation (AHWBI) following lumpectomy were confirmed by results from 12 years of follow-up in a randomized study.

Results were presented in an oral session here on December 13 at the 30th Annual San Antonio Breast Cancer Symposium (SABCS) by Tim Whelan, BM, MSc, Juravinski Cancer Centre, McMaster University, Hamilton, Ontario, Canada.

Dr. Whelan said AHWBI was as effective as standard whole-breast irradiation in every clinical parameter examined: local recurrence; overall survival; cosmetic outcome; radiation-related morbidity; and causes of eventual death.

"At 12-year median follow-up, [AHWBI] demonstrated excellent local control similar to standard whole-breast irradiation," he said. "It was not associated with any increase in long-term morbidity with respect to skin and soft tissue toxicity, breast cosmesis, or noncancer deaths."

These results should prompt broader use of AHWBI, which has been largely neglected in the United States, although it has gained considerable popularity in other countries, Dr. Whelan said. He also recommended additional clinical trials to compare this therapy and/or its combination with boost irradiation.

AHWBI delivers radiation in fewer, larger doses than in conventional whole-breast irradiation. The rationale is to overcome physicians' reluctance to undergo radiation after breast-conserving surgery based on inconvenience and cost of the longer traditional schedule. Approximately 20% to 30% of women do not receive postsurgical radiation therapy for these reasons, Dr. Whelan said.

In this study, 1,234 patients were randomized to receive AHWBI 50 Gy of radiation given in 16 doses over 22 days or a standard regimen of 42.5 Gy in 25 doses over 35 days. Only patients with node-negative disease with negative excision margins and breast width no greater than 25 cm were enrolled.

Five-year results showed a 3% rate of local recurrence in each arm and similar cosmetic outcomes, Dr. Whelan said, but concerns remained about potential differences in long-term morbidity. These were dispelled in the new analysis, with a median of 12 years of follow-up.

Recurrence rates at the 10-year mark were 6.2% for AHWBI and 6.7% for standard irradiation (not significant) and both rose to about 7.5% at 12 years. Overall survival rates were virtually identical at about 80%.

Confirming the noninferiority finding for AHWBI at 10 years was that the lower limit of the 95% confidence limit was a 2.5% advantage for standard irradiation, whereas the protocol established a 5% difference as the minimum for a finding of inferiority.

Immediately after irradiation was completed, 83% of patients receiving AHWBI and 82% of those in the standard treatment arm rated the cosmetic outcome as good or excellent. These rates declined as time went on, but at similar rates in the two arms. At the 10-year evaluation, 71% of patients given standard treatment and 70% of those in the AHWBI arm said the outcome remained good or excellent.

Total deaths, those related to cancer, and those unrelated to cancer were all similar in the two groups, Dr. Whelan said.

[Presentation title: Long-Term Results of a Randomized Trial of Accelerated Hypofractionated Whole Breast Irradiation Following Breast Conserving Surgery in Women With Node Negative Breast Cancer. Abstract 21]