Tangential Radiation Therapy Without Axillary Surgery in Early-Stage Breast Cancer: Results of a Prospective Trial

Abstract

Purpose/Objective: To determine the risk of regional nodal recurrence in patients with early-stage, invasive breast cancer, with clinically-negative axillary nodes, treated with breast-conserving surgery, ‘high tangential’ breast irradiation and hormonal therapy, without axillary surgery or use of a separate nodal radiation field. Materials/Methods: In September 1998, we opened a multi-institutional protocol to prospectively evaluate this approach. IRB approval was obtained and patients signed informed consent. Entry criteria included age > 55, clinical stage I or II breast cancer, clinically negative nodes, pathologic tumor size > 0.5 cm and < 5.0 cm, estrogen receptor (ER) or progesterone receptor (PR) positive, tumor excised with negative margins, no axillary surgery and no prior cancer. The presence or absence of lymphatic vessel invasion (LVI) was noted, but was not an exclusion factor. Patients were required to be candidates for 5 years of hormonal therapy. The superior border of the tangential radiation fields was placed as close to the humeral head as possible based on patient anatomy. Radiation consisted of 44–46 Gy to the whole breast followed by a boost to the tumor bed, for a total of 60–61 Gy. Follow-up consisted of physical examination at least every 6 months for 3 years, then at least yearly; mammograms of the treated breast were obtained 6 months after completion of radiation, then at least annually. The accrual goal was 99 patients, assuming 33 patients would be accrued per year for 3 years. The primary endpoint was regional-nodal recurrence as the first site of failure. In January 2004, the study was closed prematurely secondary to slow accrual. Results: Seventy-four patients were entered; 2 were subsequently found to be ineligible (prior cancers) but are included in this descriptive analysis. The median follow-up time is 39 months (range, 2 – 67). The median age was 74.5 years (range, 59 – 89). Median pathologic tumor size was 1.2 cm. LVI was noted in 5 patients (7%). All tumors were ER-positive. Sixty-two were HER2/neu negative (84%), 7 (9%) were positive, and 5 (7%) were indeterminate or unknown. Sixty-four patients received tamoxifen, 3 received anastrozole, 1 received letrozole and 6 did not receive hormonal therapy; 57 of 68 patients (85%) remained on hormonal therapy at the time of this analysis. No regional nodal failures or ipsilateral breast recurrences have been identified. Three patients have developed opposite breast cancer, 1 has developed distant metastases, and 2 have died of other causes. None of the 6 patients who did not receive hormonal therapy developed recurrent disease. Conclusions: In this select group of mainly older patients with early-stage hormone-responsive breast cancer and clinically-negative axillary nodes, treatment with ‘high tangential’ breast irradiation and hormonal therapy, in the absence of axillary surgery, yields a low regional recurrence rate with early follow up. Patients with these characteristics might be spared specific axillary treatment (axillary surgery or a separate nodal radiation field), including sentinel node biopsy, with its associated time, expense, and morbidity.