Breast Conservation Treatment With Radiation: An Ongoing Success Story

For women with early-stage invasive breast carcinoma, breast conservation treatment with radiation achieves equivalent breast cancer mortality and overall survival compared with mastectomy. Prospective randomized clinical trials have demonstrated no difference in survival for these two local treatment approaches, with 20-year outcomes reported in some studies. Nonetheless, the rate of mastectomy among breast cancer patients is increasing. Breast conservation treatment with radiation has been rigorously studied and validated in randomized clinical trials. The Early Breast Cancer Trialists’ Collaborative Group meta-analysis and overview of randomized trials of locoregional treatment included 10 reported clinical trials with more than 7,000 women, in which patients were randomly assigned after breast-conserving surgery (lumpectomy with or without axillary lymph node staging) to receive radiation treatment versus not, and eight reported clinical trials with more than 4,000 women, in which patients were randomly assigned to mastectomy versus breast-conserving surgery plus radiation treatment. There was no difference in breast cancer mortality or overall survival for patients randomly assigned to mastectomy compared with breast-conserving surgery plus radiation treatment. The addition of radiation treatment after breast-conserving surgery was associated with a 21.7% reduction in 10-year local recurrence (32.0% without radiation v 10.3% with radiation), a 5.4% reduction in 15-year breast cancer mortality (35.9% v 30.5%, respectively; P .0002), and a 5.3% reduction in 15-year overall mortality (40.5% v 35.2%, respectively; P .005). Thus, on the basis of randomized clinical trials with longterm outcomes, the standard for breast conservation treatment in contemporary practice includes breast-conserving surgery plus definitive radiation treatment (including radiation to the whole breast). Despite rigorous scientific validation and level I evidence supporting breast conservation treatment with radiation, recent data indicate that the rate of mastectomy is increasing. Although the reasons for this increase in the rate of mastectomy are unclear, possible reasons include a greater awareness of patients at high risk (for example, a known or suspected mutation in BRCA1 or BRCA2), the growing utilization of breast magnetic resonance imaging (MRI), and the lack of adequate patient counseling and education about the increasingly complex menu of local treatment options. The use of breast MRI has been associated with an increase in ipsilateral mastectomy rates. For patients with breast cancer, the use of contralateral prophylactic mastectomy, including bilateral mastectomy, is also increasing and has been associated with the use of breast MRI. In this context, a model to predict the rate of local recurrence after breast conservation treatment with radiation for the individual patient could prove valuable as a source of information in the clinical setting. In the current issue of Journal of Clinical Oncology, such a model, IBTR! (ipsilateral breast tumor recurrence), is evaluated by Sanghani et al. The IBTR! model uses clinical and pathologic factors to predict the 10-year rate of local recurrence after breast conservation treatment with radiation. The good news for patients is that the rate of local recurrence after breast conservation treatment with radiation has been declining and is relatively low in contemporary practice. For recently treated patients, most studies estimate that the rate of local recurrence is approximately 5% at 10 years (approximately 0.5% per year after treatment). For such recently treated patients, low rates of local recurrence have been documented in retrospective institutional studies as well as in randomized cooperative group studies, including studies by the National Surgical Adjuvant Breast and Bowel Project. Although the global rate of local recurrence after breast conservation treatment is low, individual patients may be at greater or lesser risk for local recurrence depending on individual risk factors. IBTR! may be useful in this regard to estimate the 10-year risk of local recurrence for individual patients and to reassure the individual patient about her specific low risk of local recurrence. Decision aids have been shown to improve the ability of physicians to counsel and educate patients and to alleviate anxiety. The use of patient, tumor, and treatment factors for predicting local recurrence has a long history and a large literature. Numerous factors have been suggested but are not consistent from study to study. The IBTR! model uses seven factors to predict the 10-year rate of local failure; these are patient age, tumor size, tumor grade, margin status, lymphovascular invasion, use of chemotherapy, and use of hormonal therapy. These factors are reasonable choices for modeling local recurrence risk. One of the problems in developing a model such as IBTR! is that the literature supporting various individual factors is largely retrospective in nature, and individual variables often cannot be controlled in randomized clinical trials. For example, patient age is one of the strongest factors correlated with local failure, but patient age, of course, cannot be controlled in retrospective or prospective research studies. Although patient age is one of the strongest and most reproducible factors, it is possible that age represents a surrogate for undefined biologic factors. JOURNAL OF CLINICAL ONCOLOGY E D I T O R I A L VOLUME 28 NUMBER 5 FEBRUARY 1