Radiation Improves Survival in Elderly Breast Cancers, But…

Nick Mulcahy

November 07, 2012

BOSTON, Massachusetts — Women 70 years and older gain a survival benefit from radiotherapy after lumpectomy for early-stage breast cancer, according to a large retrospective analysis presented here at the American Society for Radiation Oncology 54th Annual Meeting.

The finding is important because it is at odds with the results of a major clinical trial, said lead study author Randi Cohen, MD, from the University of Maryland School of Medicine in Baltimore, during a meeting press conference. That trial, known as the Cancer and Leukemia Group B (CALGB) 9343 trial, found that there was no significant difference in survival between older women with early breast cancer treated with radiation and lumpectomy and those treated with lumpectomy alone.

In discussing the difference between the conclusions of the 2 studies, Dr. Cohen admitted that there could have been selection bias in the population she and her colleagues studied. The radiotherapy patients might have been "healthier" than those who received only surgery; a portion of the surgery-only patients might not have been robust enough for the additional treatment with radiation, she explained.

The researchers used the Surveillance, Epidemiology, and End Results (SEER) database to identify nearly 30,000 women in the United States with the same favorable breast cancer features as those in the CALBG trial.

The women were 70 to 84 years of age when they were diagnosed with clinical stage I estrogen-receptor-positive breast cancer and had survived at least 1 year. About three quarters (76%) underwent radiation after lumpectomy.

In women treated with radiation and a lumpectomy, the overall survival rate was 88.6% at 5 years, 65.0% at 10 years, and 39.6% at 15 years. In women treated with lumpectomy only, the overall survival rate was 73.1% at 5 years, 41.7% at 10 years, and 20.0% at 15 years.

The breast-cancer-specific survival rates were also superior at each time point for the women who were treated with radiation and a lumpectomy.

Median survival was 13.1 years for patients treated with radiation and a lumpectomy, and 11.1 years for patients treated with surgery alone. It was not known how many women received hormonal therapy.

In a multivariate analysis that controlled for age, tumor size, race, ductal histology, lymph nodes, and marital status, there were also significantly worse outcomes with surgery alone. Women treated only with surgery were 1.5 times as likely to die (hazard ratio [HR], 1.56) as women treated with radiation and a lumpectomy, and also had a higher disease-specific risk for death (HR, 1.41).

Use Radiation Selectively in Older Women

The omission of radiotherapy is "reasonable" in women older than 70 years who have "frailties," said Bruce Haffty, MD, from the Cancer Institute of New Jersey and the Robert Wood Johnson Medical School in New Brunswick. He moderated the press conference at which Dr. Cohen spoke. However, "there is a clear benefit in local control" with radiation that makes the treatment worth pursuing in someone with a long life expectancy, he said, referring to recurrence data, including those from the CALBG trial.

"Elderly patients should not be denied radiation simply because of their age," Dr. Haffty said.

A similar, but slightly different, conclusion was reached by investigators from the University of Texas M.D. Anderson Cancer Center in Houston, who also analyzed SEER data (Cancer. 2012;118:4642-4651).

That study, published in August and reported at that time by Medscape Medical News, showed that at 10 years, radiation therapy was associated with a lower absolute risk for mastectomy in the same breast, compared with no radiation therapy (3.2% vs 6.3%).

However, the Texas investigators also looked for and found subgroups of elderly women who were more likely than others to benefit from radiotherapy. They include patients with high-grade early breast cancers (who had a 6.7% absolute reduction in the 10-year risk for mastectomy), patients who undergo the less-sophisticated clinical lymph node assessment (4.9% absolute reduction), and any patient 70 to 74 years of age (3.8% absolute reduction).

Conversely, in subset analyses, that team found that radiation therapy provided no benefit (in terms of mastectomy) for patients 75 to 79 years of age without high-grade tumors who had a pathologic lymph node assessment.

The authors have disclosed no relevant financial relationships.

American Society for Radiation Oncology (ASTRO) 54th Annual Meeting: Abstract 82. Presented October 29, 2012.