American Society of Clinical Oncology 2009: Partial-Breast Irradiation Remains Investigational, But Does Not Diminish Survival
ORLANDO, June 9, 2009 — In a meta-analysis comparing partial-breast irradiation (PBI) with whole-breast radiation therapy (WBRT) among women with early stage breast cancer, there were no significant differences in overall survival or the development of metastases between the 2 groups, according to a meta-analysis presented at the American Society of Clinical Oncology (ASCO) 45th Annual Meeting.
"Partial-breast irradiation may be safe and feasible for women with early stage breast cancer because it does not jeopardize patient survival or the risk of metastasis," said coauthor Davide Mauri, MD, from the General Hospital of Lamia in Greece.
However, women who received PBI were twice as likely to have cancer recur in the same breast as the primary tumor, and 3 times more likely to have disease recur in the axillary lymph nodes, Dr Mauri noted during an ASCO press conference.
Notably, Dr Mauri also said that PBI should be considered investigational until the results of ongoing clinical trials can be analyzed.
This opinion was echoed by another breast cancer expert at the meeting.
"Caution is the word here," Julie Gralow, MD, told Medscape Oncology. Dr Gralow is a member of the Fred Hutchison Cancer Research Center in Seattle, Washington, and of the ASCO Communications Committee.
"This meta-analysis is not going to change practice," she continued. "The patients who had partial breast irradiation in the analysis were very low risk in the first place."
Dr Gralow also noted that there was limited randomized evidence (3 trials and a total of 1140 patients) and that the studies used a variety of irradiation techniques.
Dr Gralow also suggested that, in the case of PBI, clinicians should not confuse marketing with robust medical evidence. The new technique is being marketed aggressively by cancer clinics in some areas, she noted. "When I visit New York City, I see roadside billboards on the way in from the airport that say, 'Come to us and get radiation in 5 days'," she said.
Still, Dr Gralow acknowledged the appeal of PBI, which can be given during a 5- to 10-day period after surgery. "Whole-breast radiation takes 6 weeks, Monday to Friday, and typically we add a boost that extends it to 7 weeks," she said.
As an oncologist practicing in Seattle, in which patients travel from as far as Alaska, Montana, and Idaho, Dr Gralow said that the convenience of PBI could be a great help, logistically and financially, for the appropriate patients.
In addition, PBI "looks good cosmetically," she said, explaining that the approach might produce less tissue fibrosis and scarring.
The ongoing trials, which will further inform clinicians about the value of PBI include the joint National Surgical Adjuvant Breast and Bowel Project B39/Radiation Therapy Oncology Group 0413, said Dr Gralow.
This phase 3 randomized trial will compare the effectiveness of PBI and WBRT after lumpectomy for early stage breast cancer, she explained. The outcomes being examined include overall survival, recurrence-free survival, and distant disease-free survival.
PBI in the study will involve 3 different technologies: high-dose-rate multicatheter brachytherapy; high-dose-rate single catheter balloon brachytherapy (MammoSite; Hologic, Inc, Bedford, MA); and 3-dimensional conformal external beam radiation therapy. "Three-D conformal is most likely to be used in the study because it does not require special equipment and uses the same machine as whole-breast irradiation," said Dr Gralow.
In the meta-analysis of 3 trials that was presented at the meeting, the Greek investigators found no statistically significant difference between the PBI and WBRT groups with regard to death (odds ratio [OR], 0.912; 95% confidence interval [CI], 0.674–1.234; P = .55). "For each patient who will die from the whole-breast radiation treatment, 1 will die from the partial-breast radiation technique," said Dr Mauri.
There was also no statistically significant difference between the 2 treatment approaches with distant metastasis (OR, 0.74; 95% CI, 0.506–1.082; P = .12) or supraclavicular recurrences (pooled OR, 1.415; 95% CI, .278–7.202; P = .56).
However, PBI was statistically significantly associated with an increased risk for both local (pooled OR, 2.15; 95% CI, 1.396–3.312; P = .001) and regional disease recurrences (pooled OR, 3.43; 95% CI, 2.058–5.715; P <.0001), compared with WBRT. These increased risks did not influence overall survival, reminded Dr Mauri.
Dr Mauri also said the locoregional recurrence rate "should not alarm." He explained that 2 of the 3 studies in the analysis used a standardized field of radiation, irrespective of the tumor size, which could have led to areas of disease being missed, increasing recurrence. "This explanation makes the finding of increased local recurrence less concerning," he said, adding that the issue needs to be further addressed.
Source: Medscape Medical News
