Stage I, II, IIIA, and Operable IIIC Breast Cancer
Patients whose tumors have these characteristics may benefit from a more generous initial excision to avoid the need for a re-excision.[21,22]
Radiation therapy (as part of breast-conserving local therapy) consists of postoperative external-beam radiation therapy (EBRT) to the entire breast with doses of 45 Gy to 50 Gy, in 1.8 Gy to 2.0 Gy daily fractions over a 5-week period. Shorter hypofractionation schemes achieve comparable results.[23,24,25] A further radiation boost is commonly given to the tumor bed. Two randomized trials conducted in Europe have shown that using boosts of 10 Gy to 16 Gy reduces the risk of local recurrence from 4.6% to 3.6% at 3 years (P = .044),[Level of evidence: 1iiDiii] and from 7.3% to 4.3% at 5 years (P < .001), respectively.[Level of evidence: 1iiDiii] If a boost is used, it can be delivered either by EBRT, generally with electrons, or by using an interstitial radioactive implant.
The age of the patient should not be a determining factor in the selection of breast-conserving treatment versus mastectomy. A study has shown that treatment with lumpectomy and radiation therapy in women 65 years and older produces survival and freedom-from-recurrence rates similar to those of women younger than 65 years. Whether young women with germ-line mutations or strong family histories are good candidates for breast-conserving therapy is not certain. Retrospective studies indicate no difference in local failure rates or overall survival (OS) when women with strong family histories are compared with similarly treated women without such histories.[30,31][Level of evidence: 3iiiDii] The group with a positive family history, however, does appear more likely to develop contralateral breast cancer within 5 years. This risk for contralateral tumors may be even greater in women who are positive for BRCA1 and BRCA2 mutations.[Level of evidence: 3iiiDii] Because of the available evidence indicating no difference in outcome, women with strong family histories should be considered candidates for breast-conserving treatment. For women with germ-line mutations in BRCA1 and BRCA2, further study of breast-conserving treatment is needed.
Breast-conserving surgery alone without radiation therapy has been compared with breast-conserving surgery followed by radiation therapy in six prospective randomized trials (including the National Surgical Adjuvant Breast and Bowel Project's trial [NSABP-B-06] and the Cancer and Leukemia Group B's trial [CLB-9343]).[6,33,34,35,36,37] In two of these trials, all patients also received adjuvant tamoxifen.[36,37] Every trial demonstrated a lower in-breast recurrence rate with radiation therapy, and this effect was present in all patient subgroups. In some groups, for example, women with receptor-positive small tumors  and those older than 70 years, the absolute reduction in the rate of recurrence was small (<5%). The limited impact of radiation therapy in this group of women was also reported in a confirmatory observational study looking at in-breast control rates using the Surveillance, Epidemiology, and End Results (SEER)-Medicare database. The impact of radiation therapy on local control was additionally clarified by showing that healthy women aged 70 to 79 years were most likely to benefit from radiation therapy (number needed to treat [NNT] to prevent one event = 21-22 patients) when compared to women aged 80 years or older or to those who have comorbidities (NNT = 61-125 patients). The administration of radiation therapy may be associated with short-term morbidity, inconvenience, and potential long-term complications.