Breast Cancer

PV QA 4 - Poster Viewing Q&A 4

TU_4_3358 - Utilization and Toxicity of Breast Boost Radiation Therapy Following Hypofractionated Whole Breast Irradiation: Comparative Analysis of a Large, Statewide Multicenter Cohort

Tuesday, October 23
2:45 PM - 4:15 PM
Location: Innovation Hub, Exhibit Hall 3

Utilization and Toxicity of Breast Boost Radiation Therapy Following Hypofractionated Whole Breast Irradiation: Comparative Analysis of a Large, Statewide Multicenter Cohort
T. P. Boike1,2, K. Griffith3, R. Jagsi4, J. M. Moran4, J. Radawski5, J. T. Dilworth6, M. M. Dominello7, J. A. Hayman4, F. A. Vicini8,9, and L. J. Pierce10; 1McLaren Northern Michigan, Petoskey, MI, 2Karmanos Cancer Network, Detroit, MI, 3Department of Biostatistics, University of Michigan, Ann Arbor, MI, 4University of Michigan, Ann Arbor, MI, 5West Michigan Cancer Center, Kalamazoo, MI, 6Beaumont Health System, Troy, MI, 7Karmanos Cancer Institute, Detroit, MI, 8Michigan Healthcare Professionals, Farmington Hills, MI, 921st Century Oncology, Farmington Hills, MI, 10Michigan Medicine, Ann Arbor, MI

Purpose/Objective(s): Little is known about current patterns of breast boost radiotherapy (boost) use or its acute toxicity, especially after hypofractionated whole breast irradiation (H-WBI), now the recommended regimen for most node-negative patients. We evaluated prospectively collected data from a statewide multicenter cohort to understand factors associated with utilization and acute toxicity of boost after H-WBI.

Materials/Methods: We analyzed patients within our database from 2012 to 2017. 6,133 women were evaluable from 23 radiation oncology clinics. We excluded patients with nodal treatment (15.3%), and missing demographic/treatment/toxicity information (8.4%). Of the remaining 4,761 women, 2,409 women received H-WBI and constituted the analytic sample. Sociodemographic, clinical, and treatment characteristics were analyzed for association with the use of boost. Patients and physicians reported toxicity weekly during treatment and at the end of treatment -4/+7 days (EOT). Maximal toxicity from the first three weeks of treatment was compared to toxicity at the EOT for patients receiving boost and not. We additionally created a multiple variable model of the association between boost receipt and toxicity, adjusting for age, race, comorbidities, smoking status, nodal disease, chemotherapy, endocrine therapy, separation distance, breast volume, and use of IMRT for the H-WBI.

Results: Of the 2,409 women, 19% were treated without boost and 81% received boost. The most common H-WBI regimens utilized were 42.56 Gy/16 fractions (80% of cases) and 40 Gy/15 fractions (10% of cases). The most common boost regimens were 10-10.64 Gy/4 fractions (51%), 10 Gy/5 fractions (31%), or 12 Gy/6 fractions (8%). Boost was delivered less often in women with increasing age and comorbidities. The percent of women receiving boost was 79% for age 51-60, 66% for age 61-70, and 48% for age greater than 71. Patients with close margins, positive margins, ER negative disease, Her2 positive disease, African Americans, and women having received chemotherapy were more likely to receive boost. Maximal pain scores were similar between boost and non-boost cases up to 3 weeks (OR = 0.95, 95% CI: 0.68 – 1.34), p=0.786, yet statistically different at EOT (OR=1.52, 95% CI: 1.10 – 2.12), p=0.012 when adjusted for important confounders. At EOT, moderate/severe pain was reported in 11.0% of non-boost cases and 19.5% of boost cases.

Conclusion: In this large, multi-center cohort, treatment with boost was used frequently in conjunction with H-WBI and personalized based on patient characteristics. The observed differences in acute toxicity constitute relevant considerations in decision-making about boost use (especially in the large group for whom current consensus guidelines make no clear recommendation), in conjunction with existing evidence regarding efficacy, long term side effects, and cost.

Author Disclosure: T.P. Boike: Partner; Petoskey Radiation Oncology. Honoraria; ASTRO APEx Reviewer. Member; NCI Prostate Cancer Task Force. K. Griffith: None. R. Jagsi: Research Grant; American Cancer Society, NCCN, Breast Cancer Research Foundation, Abbott and Abbvie Pharmaceuticals. Advisory Board; Eviti. Research Committee Chair; Radiation Oncology Institute. Board of Directors; ASCO. J.M. Moran: Research Grant; Varian Medical Systems, Blue Cross Blue Shield of Michigan, NIH. We have a collaboration regarding the use of gel dosimetry. Modus Medical supplies gels for the research.; Modus Medical Devices. Consultant; Chartrounds, St. Jude Children's Research Hospital, VA National Center for Patient Safety. Travel Expenses; AAPM, St. Jude Children's Research Hospital. Chair; AAPM. J.T. Dilworth: None. M.M. Dominello: None. J.A. Hayman: Research Grant; Blue Cross Blue Shield of Michigan. F.A. Vicini: Member; ATIC. Co-Chair; NRG. PI; NSABP, RTOG. L.J. Pierce: Royalty; UpToDate.

Thomas Boike, MD

Disclosure:
Employment
Karmanos Cancer Institute: Network Medical Director: Employee; Petoskey Radiation Oncology: MD: Partner

Compensation
ASTRO APEx Reviewer: Honoraria

Leadership
NCI Prostate Cancer Task Force: Member

Biography:
Tom Boike MD, MMM is a community radiation oncologist who is also active in network leadership within the Karmanos Cancer Institute. Along with clinical duties, my network job includes chairing our quality committee. I have also been active in ASTRO serving as an APEx quality reviewer and participate in the payor relations committee. Outside of work I have an awesome family with two daugters. We love playing outside in all the great seasons Michigan has to offer.

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