Abstract P1-10-15: Pentoxifylline and vitamin E therapy compliance in patients with breast fibrosis following adjuvant radiotherapy
Authors: Famoso JM , Gonzalez VJ , McBride A 
Published: March 2017

Purpose: Radiation therapy is an important treatment modality in the curative management of early stage breast cancer. With increasing cancer survivorship, late effects of cancer treatment have become increasingly relevant. Breast fibrosis is a common late effect following therapeutic irradiation which can potentially result in pain, poor cosmesis, and functional impairment. Randomized trials have suggested that radiation fibrosis may be reversible or preventable using a medication regimen of Pentoxifylline and Vitamin E. These clinical trials have shown excellent patient compliance and tolerability of this regimen, but it is unclear if this tolerability translates to clinical practice. The goal of this study is to investigate the clinical tolerability and compliance with pentoxifylline and Vitamin E therapy in patients with radiation induced breast fibrosis while determining possible correlates to discontinuation.

Methods: We identified ninety patients who were prescribed Pentoxifylline (400mg three time daily) and Vitamin E (400 IU once daily) following definitive breast radiation therapy from January 2013 to December 2015. A retrospective cohort study was conducted utilizing medical record analysis. Data was collected including patient age, comorbid conditions, concurrent medications, duration of pentoxifylline and Vitamin E therapy, any dose adjustments, patient reported side effects, and any reported reason for discontinuation. Multivariate analysis of correlation between medication compliance and these categorical variables was assessed with Chi squared (χ2) analysis of independence.

Results: Raw patient compliance with Pentoxifylline and Vitamin E therapy was found to be poor with 33 of 87 (38%) of patients requiring either dose reduction or discontinuation of therapy due to side effects. The majority of patient complaints leading to dose adjustments were GI related with nausea (n=20) abdominal pain (n=4), and diarrhea (n=1) reported. There was a statistically significant relationship between concurrent antiemetic therapy and successful completion of pentoxifylline regimen. Patients completed therapy at a rate of 76% with concurrent antiemetic vs 48% without (p=0.007). There was a statistically significant relationship between concurrent proton pump inhibitor therapy and discontinuation of pentoxifylline. Patients completed pentoxifylline therapy at a rate of 33% with concurrent proton pump inhibitor vs 81% without (p=&lt;0.001). Treatment compliance was not significantly correlated with age, pre-existing GERD, time since completing radiation therapy, concurrent use of aromatase inhibitor, tamoxifen, vitamin E, or chemotherapy.

Conclusion: Patient compliance with Pentoxifylline and Vitamin E for radiation induced breast fibrosis appears to be worse in clinical practice compared with previously reported randomized trials. Nausea was the most commonly reported side effect resulting in discontinuation of the regimen. Our data suggests concurrent antiemetic therapy is correlated with strong regimen compliance while concurrent proton pump inhibitor therapy is correlated with poor compliance independent of comorbid conditions. These data should be discussed with patients prior to initiation of treatment.

Citation Format: Famoso JM, Gonzalez VJ, McBride A. Pentoxifylline and vitamin E therapy compliance in patients with breast fibrosis following adjuvant radiotherapy [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-10-15.