Radiation Therapy Extends Survival in Elderly Women with Early Breast Cancer 


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Chronologic age alone should not preclude use of radiation in elderly women with early breast cancer, suggest two studies presented at the 54th Annual Meeting of the American Society for Radiation Oncology (ASTRO). Both studies showed a survival improvement in elderly women with early breast cancer treated with adjuvant radiation.

SEER Database Analysis

The first study showed that the addition of radiation therapy to lumpectomy improved overall survival as well as breast cancer–specific survival in women aged 70 or older.1

“These findings suggest that radiation should be considered as part of the treatment plan for appropriately selected elderly women. Age alone should not impact whether or not radiation treatment is presented as a viable treatment option,” stated Randi Cohen, MD, University of Maryland School of Medicine, Baltimore.

The study population was drawn from a Survival, Epidemiology, and End Results (SEER) database of 29,949 women diagnosed with stage I, estrogen receptor–positive breast cancer who underwent lumpectomy with or without adjuvant radiation and survived at least 1 year after initial diagnosis. A total of 22,781 patients (76%) received adjuvant radiation therapy.

Major Results

Median survival was 13.1 years for women treated with surgery plus radiation and 11.1 years for those treated with surgery alone. Five-year cancer-specific survival was 98.3% for the adjuvant radiation group vs 97.6% for the surgery-alone group, a statistically significant difference (P < .0001). Ten-year cancer-specific survival was 95.4% vs 93.3%, respectively (P < .0001), and 15-year cancer-specific survival was 91.4% vs 89.5%.

At all time points, the use of adjuvant radiation improved overall survival. At 5 years, overall survival was 88.6% for those who received radiation vs 73.1% for the surgery-alone arm (P < .0001); at 10 years, overall survival was 65% vs 41.7% (P < .0001); at 15 years, overall survival was 39.6% vs 20%.

The use of radiation decreased with advancing age. Between the ages of 70 and 74 years, 80% of women were treated with radiation; between the ages of 75 and 79 years, 74% received radiation; and between the ages of 80 and 84 years, 61% were treated with radiation.

Dr. Cohen said the greater differences in overall survival between groups compared to between-group differences in cancer-specific survival probably can be explained by selection bias, resulting in the administration of adjuvant radiation to healthier women with a longer life expectancy. She also said that the improvement in cancer-specific survival is likely to be related to improved locoregional control achieved by radiation.

Limitations of the study include its retrospective design and the lack of data on recurrence rates and use of hormonal therapy.

Similar Findings

A related study, also based on SEER data, found that older women with early-stage, low-risk breast cancer treated with radiation after breast-conserving surgery had superior breast cancer–specific and overall survival rates compared to women who did not undergo radiation after breast-conserving surgery.2 The study, which also explored patterns of care, found a 6% decline in use of radiation after 2004, when results of the Cancer and Leukemia Group B (CALGB) 9394 trial suggested that radiation treatment could be omitted in elderly patients without compromising cancer-specific or overall survival.3

The National Comprehensive Cancer Network (NCCN) revised its treatment guidelines in 2005 to state that omission of radiation therapy is reasonable for women over age 70 who have small estrogen receptor–positive tumors treated with adjuvant tamoxifen. Results of the present study suggest that the guidelines should be revisited.

“Our research shows that older patients with breast cancer who undergo radiation therapy after breast-conserving surgery have a higher breast cancer–specific survival than those who do not. The large number of patients and breast cancer–specific events in this study highlight clinically meaningful survival advantages among patients who received radiation in conjunction with breast-conserving surgery compared with those treated with surgery alone, which may not have been detected in earlier studies. In advancing the care of our patients, treatment recommendations should be guided by the best available evidence to date,” stated Mariam P. Korah, MD, lead author and a radiation oncologist at the University of Southern California Keck School of Medicine in Los Angeles.

Key Data

The study population included 32,885 patients with stage T1 or T2 node-negative, estrogen receptor–positive breast cancer who received breast-conserving surgery with a minimum follow-up of 3 months. The majority of included women had tumors measuring 2 cm (85%). Overall, 69% received radiation therapy after breast-conserving surgery; from 2000 to 2004, 72.1% received radiation, but from 2005 to 2009, only 66.6% received radiation. Factors associated with a greater likelihood of receiving radiation were diagnosis at age younger than 80 years, being diagnosed before 2005, and need for reexcision of the biopsy for residual disease.

Among those treated with radiation, 93% received external-beam radiation therapy. Use of brachytherapy increased over time, from less than 1% in 2000 to more than 10% by 2007, Dr. Korah said.

Breast cancer–specific survival favored radiotherapy. At 5 years, cancer-specific survival was 97% with radiotherapy vs 95% without it—an absolute difference of 2%. By 8 years, the absolute difference was doubled to 4%, favoring radiation: 95% vs 91%, respectively.

Overall survival also favored the addition of radiotherapy to surgery. Five-year overall survival was 87% vs 68% respectively, with an absolute difference of 19% favoring radiation, and 8-year overall survival was 73% vs 50%, for an absolute difference of 23% favoring radiation.

In a multivariate analysis for survival, radiation therapy remained an independent and significant predictor for both overall and breast cancer–specific survival, she said.

Benefits in Context

Putting the absolute benefits of adjuvant radiation in context, Dr. Korah said that chemotherapy is given to patients with early breast cancer for survival improvements of 2% to 3% at 5 to 10 years of follow-up.

The study’s limitations include lack of data on comorbidities, surgical margin status, hormonal therapy, and locoregional recurrence. Adjuvant hormonal therapy was already being recommended for patients with estrogen-receptor tumors during this study period. Dr. Korah estimated that about 70% to 80% of women in this study were prescribed hormonal therapy and that about 60% were compliant.

“Estimations of life expectancy, competing risk analysis, cost-effectiveness, convenience, and quality-of-life considerations become a factor in determining optimal cancer treatments for older women. Treating elderly patients is complex. We need to have a frank discussion about the benefits and side effects of our treatments, and we need to consider cost-effectiveness and quality of life. This is a moving target. We need to incorporate all the evidence to make treatment decisions,” she told listeners. ■

Disclosure: Drs. Cohen and Korah reported no potential conflicts of interest.

References

1. Cohen RJ, Li L, Citron W, et al: Improved survival with adjuvant radiation in elderly women with early stage breast cancer. 54th ASTRO Annual Meeting. Abstract 82. Presented October 29, 2012.

2. Korah MP, Sener SF, Tripathy D: Implications of omitting radiation after breast conserving surgery in elderly women with low risk invasive breast cancer. 54th ASTRO Annual Meeting. Abstract 84. Presented October 29, 2012.

3. Hughes KS, Schnaper LA, Berry D, et al: Lumpectomy plus tamoxifen with or without irradiation in women 70 years of age or older with early breast cancer. N Engl J Med 351:971-977, 2004.


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