2943 - Objective Analysis of Fibrosis via Shear Wave Elastography after Post Mastectomy Radiation
Presenter(s)
C. Hardy Abeloos1, R. A. Adler2, T. Hochman3, J. Goldberg4, O. G. Maisonet5, O. Cahlon5, C. A. Perez6, A. Solan2, and N. K. Gerber5; 1NYU Grossman School of Medicine, New York, NY, 2NYU Grossman School of Medicine, New York City, NY, 3NYU Langone Medical Center, New York, NY, 4NYU School of Medicine, New York, NY, 5New York University Grossman School of Medicine, Department of Radiation Oncology, New York, NY, 6St. Jude Children's Research Hospital, Memphis, TN
Purpose/Objective(s): Radiation induced fibrosis (RIF) can cause significant reconstruction complications in women with implant-based breast reconstruction and there is currently no objective way to measure it or track its progression. Shear wave elastography (SWE) uses acoustic impulses to measure Young’s elastic modulus (measured in kPa) and has been shown to correlate with muscle atrophy and the LENT-SOMA fibrosis score when assessing RIF in head and neck patients 1.5 years after radiation (RT). Pharmacologic blockade of the adenosine receptor has been shown to reduce skin fibrosis associated with radiation injury in murine models. As part of an ongoing phase II clinical trial randomizing patient receiving post mastectomy RT with tissues expanders to topical caffeine, which is adenosine antagonist vs placebo, patients underwent SWE to evaluate its correlation with RIF and better quantify the effect of the caffeine cream on RIF.
Materials/Methods: Women = 18 years old with breast carcinoma stage 0-III status post mastectomy with tissue expander-based reconstruction who require RT to the chest wall +/- the regional nodes were enrolled. They underwent SWE at baseline pre-RT, 6 months post RT prior to implant exchange and 2 years after RT. The Young’s elastic modulus was measured at each quadrant of the irradiated breast and averaged.
Results: 15 patients were enrolled on the SWE sub study with no differences in baseline characteristics. Two patients were excluded due to not having both baseline and post RT SWE, 1 patient was excluded due to early removal and replacement of tissue expander and 1 patient was excluded due to a ruptured expander that rendered the SWE measurements unreliable. Of the 11 remaining patients, the average Young’s elastic modulus increased for all patients except one with a mean decrease of 13.1 kPa. Seven patients received topical caffeine and 4 received placebo cream. There was no difference in time between baseline and post RT SWE between both groups (8.4 vs 8.5 months) and no difference in treatment compliance with the topical treatment between both groups (90.5% topical caffeine vs 90.4% placebo cream, p = 0.93). The average Young’s elastic modulus between baseline and post RT increased more in the patients who received the placebo cream compared to those who received topical caffeine (9.5 kPa vs 22.2 kPa p =0.109).
Conclusion: These initial results show that shear wave Young’s modulus increased from baseline pre-RT to 6 months post RT prior to implant exchange in all patients except one, suggesting that it may be a valuable tool to objectively measure fibrosis over time and may help predict those at risk for RIF complications. Furthermore, there was a trend for a greater increase in patients who received placebo compared to those who received topical caffeine, potentially suggesting that caffeine may prevent fibrosis at a cellular level. We await the 2-year data to further assess SWE accuracy and reliability as a tool to predict and quantify RIF.