BOSTON – A review of data on nearly 30,000 women suggests older age by itself should not be a barrier to radiotherapy after lumpectomy for early-stage breast cancer.
Older patients treated with both modalities had higher rates of overall and breast cancer–specific survival at 5 and 10 years compared with women who underwent lumpectomy alone, investigators reported at the annual meeting of the American Society for Radiation Oncology.
Courtesy American Society for Radiation Oncology
Dr. Randi J. Cohen
"The improvement in cause-specific survival with the addition or radiation suggests that in healthy, elderly women, adjuvant radiation should be strongly considered as part of their breast cancer treatment," said Dr. Randi J. Cohen, a radiation oncologist at the University of Maryland in Baltimore.
The review examined Surveillance, Epidemiology, and End Results (SEER) database records on 29,949 women, who were aged 70-84 years at diagnosis with clinical stage I, estrogen receptor–positive breast cancer and survived at least 1 year. About three-fourths underwent radiation after lumpectomy.
Women treated with lumpectomy and radiation had an overall survival rate of 88.6% at 5 years vs. 73.1% among those with no radiation (P less than .0001), Dr. Cohen reported. Overall survival rates at 10 years were 65.0% and 41.7%, respectively.
Cause-specific survival rates at 5 years were 98.3% for patients in the radiation plus surgery group and 97.4% for those with no radiation. At 10 years, the respective rates were 95.5% and 93.3% (P less than .0001 for both comparisons).
The median length of survival also was greater with the addition of radiotherapy – 13.1 years vs. 11.1 years with lumpectomy alone.
Radiation Was Independent Predictor
In multivariate analysis that controlled for age, tumor size, race, ductal histology, lymph nodes and marital status, hazard ratios also showed significantly worse outcomes without radiation – 1.56 in the overall survival analysis and 1.41 in the cause-specific survival analysis.
The results are similar to those in a meta-analysis from the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG), said Dr. Cohen. That study showed an absolute benefit for adding radiation of 3% at 10 years, compared with 2.2% at 10 years in the current study.
Dr. Cohen said the review was prompted by questions raised in a 2004 study from the Cancer and Leukemia Group B (CALGB). In that trial, investigators looked at whether adding radiation to lumpectomy plus tamoxifen would have an effect on overall or breast cancer–specific survival in 630 women 70 years and older with early-stage disease. They found that at a median follow-up of 10.5 years, there was an absolute reduction of 6% in same-breast tumor recurrence with radiation, but no difference overall of disease-free survival.
In the much larger EBTCG study and the current study, however, the disease-specific survival advantages with the addition of radiation were likely related to greater locoregional control. Dr. Cohen said that the overall survival advantage in her study was probably due to selection of healthier patients with longer predicted life expectancy for radiotherapy.
She noted, however, that the study was limited by a lack of data on recurrence rates or hormonal therapy.
Strength of Benefit Questioned
"It’s highly unlikely that the magnitude of the benefits of cause-specific survival can be attributed to just radiation alone," said Dr. Meema Moran, the invited discussant. She noted that in EBCTCG study, there was only about a 3% benefit at 15 years in a seemingly low-risk population with shorter follow-up. The favorable survival in the meta-analysis may therefore be partly attributable to treatment selections bias, said Dr. Moran, a radiation oncologist at Yale University in New Haven, Conn.
She also noted that because local recurrence data are not collected in SEER, mastectomy-free survival is used as a surrogate for relapse, but mastectomy rates may vary due to differences in management of ipsilateral recurrence, such as mastectomy or repeat breast-conserving surgery.
The funding source for Dr. Cohen’s study was not disclosed. She reported no conflicts of interest. Dr. Moran reported serving on the Genomic Health Advisory Board.