WINSTON-SALEM, N.C. -- Radiation therapy for most women 65 and older with stage I or II breast cancer helps prevent recurrences or second primaries, determined a multicenter team of investigators.
WINSTON-SALEM, N.C., Jan. 22 -- Radiation therapy for most women 65 and older with stage I or II breast cancer helps prevent recurrences or second primaries, found a multicenter team of investigators.
Among such women who underwent a mastectomy or lumpectomy in the early to mid 1990s, those who did not get radiation therapy had a 60% higher risk of recurrence or secondary primaries, reported Ann M. Geiger, M.P.H., Ph.D., of Wake Forest here, and colleagues.
In a records-based analysis of outcomes of than 1,800 patients, the investigators also found that breast-conserving surgery without radiation was associated with a 3.5-fold risk for local or regional recurrence of primary breast cancer, they reported in an early online release from the March 1 issue of Cancer.
Women had a benefit from adjuvant radiation regardless of their age, co-morbidities, or the use of tamoxifen (among those with hormone-sensitive tumors), the authors noted.
"Older women also are less likely to receive standard breast cancer treatments than younger women," wrote Dr. Geiger and colleagues. "Although treatment in older women may be complicated by comorbidities, impaired functional status, physiological differences, and other factors, the under representation of older women in clinical trials and in prognostic marker studies makes it difficult to determine which treatments are most appropriate for approximately 50% of women who are diagnosed with breast cancer."
To get a better idea of the effectiveness of breast cancer treatment in older women, the authors conducted a medical record-based cohort study with 10 years of follow-up among women who were 65 or older when they were diagnosed with stage I or II breast cancer, and who had a mastectomy or breast-conserving surgery while they were members of one of six community-based, integrated healthcare delivery systems.
The women were followed for 10 years or until breast cancer recurrence, dropout, or death. Abstractors reviewed their medical records to obtain data on recurrence, tumor, treatment, and demographics.
The investigators created proportional hazards models to identify potential predictors of primary tumor recurrence and second primary breast cancers, with adjustment for demographic and tumor factors.
The first set of models looked at surgery and radiotherapy, dividing the cohort into women who underwent breast conversing surgery only, breast-conserving surgery with radiation, and mastectomy. Because radiation therapy after mastectomy was uncommon in the cohort and appeared to offer little additional protection against recurrence, the authors did not consider the combination as an independent treatment.
The second set of models they created looked at hormone therapy, which in this cohort was tamoxifen only, since the women were treated before the introduction of aromatase inhibitors.
The authors identified 1,837 eligible women, 34% of them ranging in age from 65 to 69, 46% of them 70 to 79, and 20% of them 80 and older.
They found that in multivariable models using mastectomy as the reference group, women who had breast-conserving surgery without radiation therapy had a hazard ratio for any recurrent and second primary breast cancer of 1.6 (95% confidence interval, 1.1-2.3). In the subgroup of women with local or regional recurrence, the hazard ratio was 3.5 (95% CI, 2.0-6.0).
When they looked only at the 886 women with hormone-sensitive tumors who received tamoxifen but not chemotherapy, they found that there was a borderline association between any recurrence or second primary breast cancers in women who took tamoxifen for less than one year, compared with women who received it for the full five years. The hazard ratio for the short course of tamoxifen was 1.9 (95% CI, 0.9-4.2).
"We recommend that mastectomy or breast-conserving surgery with radiation therapy, along with adequate duration of adjuvant hormone therapy for patients with hormone-responsive tumors, be considered standard therapy in women of all ages and with all co-morbidity burdens, except for women with very limited life expectancies," the investigators wrote.
They acknowledged that drug therapy and surgical practice have changed considerably since the women in the cohort were diagnosed, suggesting that the findings might not be relevant to current clinical practice. But they pointed out that the women were followed for 10 years rather than the customary five, meaning that the cohort members would have more time to develop recurrent or second primary cancers.
"Assuming that treatment has advanced, our results may represent the worst-case scenario, and current treatments may be even more advantageous for older women," they wrote.