Omitting Post-lumpectomy RT Lowers Survival in Elderly

SAN ANTONIO—Elderly women are less likely to receive radiotherapy (RT) after breast-conserving surgery, an omission that has a negative impact on survival in this group, Pauline T. Truong, MD, said at the 25th Annual San Antonio Breast Cancer Symposium (abstract 29). The researchers, from the Breast Cancer Outcomes Unit, British Columbia Cancer Agency, Vancouver Island, BC, examined the impact of omitting radiation therapy among 5,557 women, age 50 to 89, with T1-2, M0 invasive breast cancer who were treated with breast-conserving surgery between 1989 and 1998. The women were stratified by age (50 to 64, 65 to 74, and 75 to 89) and by type of treatment (postsurgery radiation or no radiation). Multivariate analysis took into account patient age, tumor factors, and treatment factors. The median follow-up was 6.4 years.

The rate of omission of radiotherapy was similar in the two younger age groups—13% for the women age 50 to 64, and 14% for those age 65 to 74. But the radiotherapy omission rate was more than doubled in the oldest women, 32% of whom did not receive radiotherapy after breast-conserving surgery.

"In the comparison of tumor characteristics according to radiotherapy use, both the treated and untreated groups had similar proportions of T2 disease, presence of lymphovascular invasion, and estrogen-receptor positivity," Dr. Truong reported. "The group that did not undergo radiotherapy had lower proportions of high-grade disease. But they had higher rates of tumor involvement of the surgical margins, indicating less complete surgery in the unirradiated group."

Among patients age 75 and older, 19.2% of those who did not receive radiotherapy had positive margins, compared with 10.3% of those who did undergo postsurgery radiotherapy. In this oldest age group, 62% of the women who did not undergo radiotherapy received adjuvant tamoxifen (Nolvadex), compared with 44% of the women who did have radiotherapy.

RT Omission and Outcome

Omission of radiotherapy had a negative impact on overall 5-year survival in all age groups but was most pronounced among the oldest patients. In the entire cohort, 5-year overall survival was 89% for the radiation group vs 75% for the no-radiation group (P < .0001). For women age 50 to 64, the respective percentages were 92% vs 86% (P < .0003); for those age 65 to 74, the percentages were 89% vs 80% (P < .0001); and for those age 75 and older, the percentages were 82% vs 58% (P < .0001).

Five-year breast-cancer-specific survival in the entire cohort was 94% for patients who received radiotherapy vs 90% (P < .0001) for those who did not. Breast-cancer-specific survival differences were not significant in the two youngest groups. Among women age 75 and older, however, the survival statistics were 93% for those receiving radiotherapy vs 85% for those who did not (P < .0001). The adjusted hazard ratio for radiotherapy omission among women age 75 and older was 2.2 (range, 1.2 to 3.9).

In terms of 5-year relapse-free survival, the survival statistics among the oldest women mirrored those of the entire cohort: 98% of the radiation group was relapse-free at 5 years, compared with 93% of those who did not receive radiotherapy (P < .0001). The other age groups had similar rates.

Dr. Truong concluded that the use of radiotherapy after breast-conserving surgery declines significantly with advanced age and that omission of radiotherapy is associated with lower overall survival in all the age groups analyzed. Moreover, despite similar tumor characteristics and a higher rate of tamoxifen use, women age 75 and older who did not receive radiotherapy had a lower breast-cancer-specific survival.