Adjuvant RT Extends Survival in Elderly TNBC Patients

Adjuvant radiation therapy after lumpectomy improves survival for elderly women with early-stage, triple-negative breast cancer (TNBC), according to a new study to be presented at the 2015 American Society of Clinical Oncology (ASCO) Breast Cancer Symposium in San Francisco (abstract 39).

Adjuvant radiation therapy may be omitted for elderly women with early-stage breast cancer who have favorable estrogen-receptor status. Some studies show that elderly women with TNBC have increased recurrence rates.

“Although the existing literature shows benefit from radiation, in the subgroup of elderly women with triple-negative breast cancer it does not provide a quantitative estimate on prolonged survival. Our study breaks ground by beginning to determine that exact amount,” lead author Sean Szeja, MD, radiation oncologist at the University of Texas Medical Branch at Galveston, Galveston, Texas, told Cancer Network.

The researchers conducted a retrospective analysis of the effect of adjuvant radiation therapy on the survival of elderly women with early-stage TNBC who underwent lumpectomy. Using the Surveillance, Epidemiology, and End Result (SEER) database, they evaluated how the addition of adjuvant radiation affected the survival of women ages 70 and above with T1-2, N0, M0 TNBC.

From 2010-2011, SEER data showed 12,620 triple-negative cases. Of these, 6,980 (55%) had stage T1-2, N0, M0. Lumpectomy was used in 4,002 of these cases, including 974 lumpectomy cases of women aged 70 and above. Adjuvant radiation therapy was given in 662 (68%) cases.

After 23 months, lumpectomy plus radiation therapy led to a statistically significant improvement in overall survival (98.2%) as compared with lumpectomy alone (85.6%). Similarly, disease-specific survival improved significantly for the combination (99%) over lumpectomy only (94%). Cox regression showed radiation demonstrated improved overall survival and disease-specific survival.

Breast cancer–related deaths were more common in the lumpectomy-only group (6%) compared with the lumpectomy and radiation group (1%). “The applicability of this is broad, considering that the life expectancy of the average 70-year-old female is 16 years. Therefore, our results will enable future treatment decisions to be made with more information,” said Dr. Szeja.

When other factors were considered, such as age, tumor size, and other treatment descriptions, the use of adjuvant radiation was associated with an overall sixfold decrease in any death, as well as death from breast cancer.

The researchers note that the difference in survival observed between those who did and did not receive adjuvant radiation could be explained by other factors, such as use of adjuvant chemotherapy.

Also, with a potential for selection bias in the study, the researchers suggest that future prospective studies are needed to better define the management of early-stage TNBC in elderly patients.

Dr. Szeja said “the oncologist should consider the patients’ life expectancy outside of the setting of their cancer, as well as comorbidities, often associated with age, that may impact their benefits as well as toxicity from any treatment. The elderly are also at risk for social factors, such as limited family support, that may impede their ability to comply with treatment as well as recover from its toxicities.”

He recommended oncologists perform a comprehensive geriatric assessment to evaluate functional, cognitive, and nutritional status as well as polypharmacy risks.