Breast Cancer

PD 17 - Breast 4 -Poster Discussion

1151 - Prone Partial Breast Irradiation (PBI): Prospective Randomized Trial to Compare Five Versus Three Fractions

Wednesday, October 24
2:18 PM - 2:24 PM
Location: Room 217 A/B

Prone Partial Breast Irradiation (PBI): Prospective Randomized Trial to Compare Five Versus Three Fractions
K. Thomas, J. Kang, M. B. Fenton-Kerimian, and S. C. Formenti; Weill Cornell Medical College/New York Presbyterian Hospital, New York, NY

Purpose/Objective(s): To report preliminary results of a phase II trial (NCT02755896) of accelerated partial breast irradiation delivered prone in three versus five fractions, after breast-conserving surgery.

Materials/Methods: Postmenopausal women with Stage T1N0 breast cancer and Stage 0 DCIS (low and intermediate grade, <2cm in size) were eligible and randomized to receive either prone PBI with five 6Gy daily fractions (total dose = 30Gy) or three fractions of 8Gy delivered every other day over a 5-day period (total dose = 24Gy). Planning CT in the prone position was performed on a dedicated prone breast board. The postoperative cavity was contoured as the clinical target volume with a 1.5 cm margin added to determine the planning target volume (PTV). Primary endpoints were a comparison of post-treatment radiation fibrosis (grades 2+3), local control, and cosmetic outcomes on the 8Gy x 3 arm versus the 6Gy x 5 arm. Normal tissue constraints for uninvolved breast included a goal of less than 35% of the whole breast receiving prescription dose (Rx) and less than 60% of the whole breast receiving 50% of Rx. Adverse events were reported in case report form and followed for the duration of the trial.

Results: 70 patients were accrued; 6 patients withdrew and 2 patients failed the screening process. A total of 62 patients were randomized and are currently available for analysis (31 patients in 6Gy x 5 arm and 31 patients in 8Gy x 3 arm). Median age was 66 years (range 53-80 years). The median PTV volume was 99.8cc (range 30.6-383.6cc) and the median breast volume was 795.3cc (range 165.9-2671cc). Normal tissue constraints were met for 100% of patients. Within a median post-treatment follow up time of 6 months, no serious radiation-related adverse event occurred. Maximum adverse event was grade 2 (radiation dermatitis), which occurred in one patient. Grade 1 breast/cutaneous event occurred in 31 additional cases. These events included 13 in the 8Gy x 3 arm and 18 in the 6Gy x 5 arm. At the one week time point, there were 14 acute skin toxicities (7 events in the 6Gy x 5 arm and 7 events in the 8Gy x 3 arm). These events included radiation dermatitis (10) and hyperpigmentation (2), and mild breast pain (2). All these events were Grade 1. At the one-month time point, 18 total radiation-associated breast/cutaneous events occurred (11 events in the 6Gy x 5 arm and 7 events in the 8Gy x 3 arm). These events included radiation dermatitis (8) pigmentation change (3), edema (2) rash (3) and mild breast pain (2). There was one Grade 2 event of radiation dermatitis, which occurred by the 1 month time-point.

Conclusion: This preliminary data suggest comparable tolerability of the 2 accelerated approaches with only mild acute side effects.

Author Disclosure: K. Thomas: None. J. Kang: None. M.B. Fenton-Kerimian: None. S. Formenti: Research Grant; Janssen Pharmaceutials (J&J). Honoraria; Regeneron Pharmaceuticals. Consultant; Regeneron Pharmaceuticals, Eli Lilly. Speaker's Bureau; Regeneron Pharmaceuticals, Varian. Advisory Board; BMS, Smith Kline, Astra Zeneca, EISAI. Travel Expenses; Regeneron Pharmaceuticals.

Kimberly Thomas

Disclosure:
No relationships to disclose.

Presentation(s):

Send Email for Kimberly Thomas


Assets

1151 - Prone Partial Breast Irradiation (PBI): Prospective Randomized Trial to Compare Five Versus Three Fractions



Attendees who have favorited this

Please enter your access key

The asset you are trying to access is locked. Please enter your access key to unlock.

Send Email for Prone Partial Breast Irradiation (PBI): Prospective Randomized Trial to Compare Five Versus Three Fractions