Effect of Immunohistochemically Biological Expression on Clinical Outcome for Patients With Breast Cancer and 1–3 Positive Lymph Nodes After Mastectomy Without Adjuvant Radiation Therapy Under Present Day Systemic Treatment

Abstract

(WBRT) for breast cancer in patients with a minimum reported follow-up of 1 year. Materials/Methods: Seventeen participating centers logged 518 patients on a privacy-encrypted online data registry. Patients had early stage breast cancer and completed HDR Ir192 breast boost using NIBB in combination with WBRT after breast conserving surgery (BCS) from July 2007 to December 2014. Recorded information included patient, tumor and treatment characteristics, as well as toxicity, cosmesis, and recurrence data. This report focuses on patients with one year minimum follow-up (nZ163). Results:Median follow-up was 23.5 months (12-75 months) and median age was 59 (range 19-87). Average tumor size was 1.5 +/1.07cm with histologies of invasive ductal (61%), DCIS (24%), and invasive lobular (9%). Reported treatment technique included average boost dose 10.6 +/3.4 Gy, utilizing clips for tumor bed identification 71% and having skin flash 34%. There were 4 reported recurrences; 2 were ipsilateral breast, but only one was within the boost volume. Entire cohort had freedom from any recurrence of 97%. Excellent or good (E/G) cosmesis at last follow-up was 96.9% with 4 (2.5%) fair and 1 (0.6%) poor. E/G cosmetic results were not statistically different between patients that received boost treatment before (93%), during (95%), or after (97%) WBRT. Analysis by increasing follow-up length showed trend for preserved cosmetic results, E/G cosmesis for patients with > 24 month follow-up (nZ63) was 95%, > 36 months (nZ32) was 100%, and > 48 months (nZ16) was 100%. Although academic centers more commonly had patients with >1 year follow-up (70%) data entered, there was no difference between E/G cosmetic rates 95% reported at academic centers vs. 96% at community centers. Conclusion: NIBB has previously been reported as a feasible alternative method to delivery breast tumor cavity boost that improves set-up reproducibility through elimination of respiratory motion and daily mammographic tumor cavity identification. This report reviewed patient outcomes with minimum of 1 year follow-up to provide valuable updated information demonstrating preserved favorable cosmetic outcome and low rates of recurrence. There was no trend for worse cosmesis or recurrence between academic and community-based practices. Author Disclosure: J.M. Schuster: None. C. Chipko: None. C.A. Quiet: None. R.K. Benda: None. S.J. Sha: None. A.M. Kuruvilla: None. C.S. Anderson: None. K. Leonard: None. D.E. Wazer: Advisory Board; Advanced Radiation Therapy. President; American Brachytherapy Society. J.T. Hepel: None. D.W. Arthur: Consultant; Impedimed. Advisory Board; Advanced Radiation Therapy.