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Omitting Post-lumpectomy RT Lowers Survival in Elderly

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).

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