Clinical Experience Using Accelerated Partial Breast Irradiation for Ductal Carcinoma In Situ

Abstract

To the Editor:Breast-conserving therapy (BCT) has becomestandard care as an alternative to mastectomy in thetreatment of most women with early stage 0, I, and IIbreast cancer (1). BCT includes tumor excision bymeans of lumpectomy followed by a course of dailyfractions of external beam radiation therapy to thewhole breast (45–50 Gy), which can be, and often is,followed by a boost to the tumor bed with an addi-tional 6–10 fractions, which achieves a total dose of60–64 Gy. These treatments typically span 5–7 weeks.Studies looking at the patterns of failure and localrecurrence for patients with breast cancer found thatthe majority (about 90%) of early breast local recur-rences occurred at the site of the original primarytumor (2). This observation and the desire to shortenthe treatment times led to the idea of using acceleratedpartial breast irradiation (APBI), which concentratesthe dose of radiation at the site of the lumpectomycavity and simultaneously limits the dose to otherstructures. This type of therapy is typically given over5 days, which not only reduces the toxicity of irradia-tion but also reduces the total treatment time.Results from trials studying the efficacy of APBIhave been encouraging, in that multiple techniqueshave been effective in maintaining excellent local con-trol and cosmetic outcomes with minimal toxicity(3–6). Several phase III randomized studies of APBIare under way; in addition, we are awaiting the resultsof the National Surgical Adjuvant Breast and BowelProject B 39/Radiation Therapy Oncology Group0413 protocol (B-39) large phase III trial that com-pares ABPI to whole breast irradiation (WBI) in earlystage breast cancer, which is finishing accrual in thenear future (7–10).Ductal carcinoma in situ (DCIS) comprises approxi-mately 25% of all cases of breast cancer diagnosedeach year (1). The National Comprehensive CancerNetwork (NCCN) guidelines continue to recommendBCT with standard adjuvant WBI as a category 1 rec-ommendation for DCIS (11). This recommendation isbased on the results of multiple randomized controlledtrials (12,13) demonstrating the efficacy of this com-bined modality approach. Specifically, these studiesreport an approximate 50% relative risk reduction inlocal control with the addition of adjuvant RT. Nosubgroup of patients with DCIS has proved not tobenefit from postoperative radiotherapy (14,15). In2002, DCIS was included as acceptable for APBI inthe American Society for Breast Surgeons (ASBS)guidelines. The APBI Consensus Statement Task Forceof the American Society for Radiation Oncology(ASTRO) classifies the subset of patients with pureDCIS as “cautionary,” with a recommended tumorcutoff size of 3 cm (16). Recent publications haveshown excellent 5-year follow-up results in patientswith DCIS treated with APBI (17–20).At our institutions we have noted low recurrencerates and excellent or good cosmesis outcomes in100% of the patients treated with APBI after breastconservation surgery (BCS) for patients with DCIS.This letter is in response to requests from brachythera-py specialists to publicize institution-specific dataregarding the use of APBI to treat breast cancer. Wehave now treated over 40 patients with stage 0 breastcancer treated with BCS and adjuvant APBI. Allpatients had biopsy-proven DCIS, and three patientsalso had an invasive component along with DCIS.With a median follow-up was 27 months (range,0–72 months, the overall and cause-specific survivalrates were 95% and 100%, respectively. The24-month actuarial ipsilateral breast tumor recurrence(IBTR) rate was 2.5%, with one patient having arecurrence. Another patient developed a contralateral