Breast Cancer

SS 23 - Breast 3?- General

158 - Five-Year Results of a Prospective Phase 2 Trial Evaluating Three-Week Hypofractionated Whole Breast Radiation Therapy with Boost

Tuesday, October 23
1:00 PM - 1:10 PM
Location: Room 303

Five-Year Results of a Prospective Phase 2 Trial Evaluating Three-Week Hypofractionated Whole Breast Radiation Therapy with Boost
A. Gupta1, A. J. Khan2, S. J. Wang1, N. Yegya-Raman1, S. Ahlawat1, N. Ohri1, S. Goyal3, D. F. Moore4, F. Eladoumikdachi1, D. Toppmeyer1, and B. G. Haffty Jr1; 1Rutgers Cancer Institute of New Jersey, New Brunswick, NJ, 2Memorial Sloan Kettering Cancer Center, New York, NY, 3George Washington University Hospital, Washington, DC, 4Rutgers School of Public Health, Piscataway, NJ

Purpose/Objective(s): Hypofractionated whole breast radiotherapy (HF-WBRT) is being increasingly used in the treatment of breast cancer. The most widely used hypofractionated regimens are delivered over three to four weeks, with an optional tumor bed boost over one or more weeks. We conducted a Phase 2 trial of HF-WBRT completed in three weeks inclusive of a sequential boost. Previous report on an initial cohort at short-term follow-up showed excellent rates of tumor control, toxicity, and cosmesis. In this planned expansion cohort, we sought to evaluate longer-term cosmesis and outcomes in a larger number of patients.

Materials/Methods: Women with Stage 0-IIIA breast cancer were enrolled on a prospective, Phase 2 trial of HF-WBRT with boost after lumpectomy. Patients with DCIS through T2N2a invasive cancers were eligible. We delivered a whole breast dose of 36.63 Gy in 11 daily fractions of 3.33 Gy (EQD2 = 45 Gy) followed by a tumor bed boost of 13.32 Gy in 4 daily fractions of 3.33 Gy over a total of 15 treatment days (Total EQD2 = 61 Gy). When indicated, regional nodal irradiation (RNI) was delivered in 11 fractions of 3.33 Gy to 36.63 Gy. Primary endpoints were locoregional control and acute and late toxicity. Cosmesis was scored using the Harvard Cosmesis Scale.

Results: Between 2009 and 2017 we enrolled 150 patients, of whom 146 received the protocol treatment and were included in the analysis. Median age was 54 years (range 33-82), with 48 patients (33%) ≤ 50 years old. Median follow-up was 47 months, with 69 patients (47%) having at least five years of follow-up. Receptor status was ER+ (79%), PR+ (75%), HER2+ (10%), and ER-/PR-/HER2- (11%). Sixteen patients (11%) received RNI, 17 patients (12%) received neoadjuvant chemotherapy, and 35 patients (24%) received adjuvant chemotherapy. Cosmesis was good or excellent in 97% of evaluable patients, remaining at 94% in patients with at least two years of follow-up. Acute grade 2 and 3 toxicities were observed in 30% and 1% of patients, respectively. Late grade 2 and 3 toxicities were observed in 9% and 3% of patients, respectively. There were no Grade 4 or 5 toxicities. Five-year freedom from locoregional failure was 97.1% (95% confidence interval [CI]: 91.1%-99.1%). Five-year freedom from distant failure was 97.4% (95% CI: 92.1%-99.2%). Five-year breast cancer-specific and overall survival were 98.9% (95% CI: 92.8%-99.9%) and 97.8% (95% CI: 91.6%-99.5%), respectively.

Conclusion: Our phase 2 trial offers one of the shortest courses of HF-WBRT, delivered in 15 fractions inclusive of a standardized sequential boost. The study cohort is representative of a broad spectrum of conservatively-treated breast cancer patients including a high percentage of young women and women requiring chemotherapy and/or RNI. With extended follow-up there continues to be excellent locoregional control and low toxicity with good to excellent cosmetic outcomes.

Author Disclosure: A. Gupta: None. A.J. Khan: Research Grant; Elekta, Cianna Medical. Consultant; Elekta. S. Wang: None. N. Yegya-Raman: None. S. Ahlawat: None. S. Goyal: Employee; Princeton Medical Group. Independent Contractor; Isoray Medical, Hines Associates. Research Grant; American Lung Association. Consultant; Hines Associates. Travel Expenses; American Lung Association. Senior Editor; Advances in Radiation Oncology. Division Chief; George Washington University. F. Eladoumikdachi: None. D. Toppmeyer: None. B.G. Haffty: Research Grant; Breast Cancer Research Foundation. Board of Directors-Science Liaison; RSNA.

Apar Gupta, MD, MBA

Disclosure:
No relationships to disclose.

Biography:
I completed a combined seven-year BA/MD program at Boston University and received a MBA during medical school. I'm currently a PGY-4 resident at Rutgers Cancer Institute of New Jersey with research interests in breast hypofractionation and value-based medicine. I currently serve on the ASTRO Payer Relations Committee and I'm actively investigating the burden of prior authorization on radiation oncology practices.

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