Abstract 4683: Neuropathic pain in breast cancer patients undergoing radiotherapy

Abstract

Abstract Post-surgery radiotherapy (RT) significantly reduces recurrence of early-stage breast cancer. However, many patients experience side effects from RT, such as neuropathic pain (NP), experienced by one third of patients during RT. Breast cancer survivors report moderate to severe NP symptoms, including hypersensitivity to cold/mechanical stimuli, itching, and numbness, which not only impact patient's functional performance and health-related quality of life, but also may interfere with treatment. Therefore, we evaluated prevalence of pain and neuropathic pain symptom (NPS) in 330 breast cancer patients undergoing RT for changes over time in these pain scales, and to determine the effect of body mass index (BMI) on the RT-induced NP (RINP) at baseline, immediately post-RT, and 1 month after completion of RT. Pain prevalence was assessed using Brief Pain Inventory (0-10) for pain at the worst over the past 4 weeks. NPS index (NPSI, 0-33) was developed using 9 questions from the National Surgical Adjuvant Breast Cancer and Bowel B39 Quality of Life questionnaire specific for breast cancer patients. Changes in these pain scales over time were assessed using a multivariate mixed model. The study consists of 56 Non-Hispanic Whites, 209 Hispanic Whites, and 66 African Americans. There were significant racial/ethnic differences in BMI (p<0.001) and cancer stage at diagnosis (p=0.018). About 85% of cases received the standard RT (50-50.4 Gy in a 200 cGy fraction) and 83% received boost of 10 Gy to the breast scar. Pain prevalence changed over time (p<0.001): 58% at baseline, 78% at the end of RT, and 71% at 1 month after RT. NPSI also changed over time; 4.9 at baseline, 10.0 at the end of RT, and 6.7 at 1 month after RT. There were significant differences in NPSI by race/ethnicity and BMI. Obese patients have worse NPS at RT completion and 1 month after RT compared to women with BMI<30. Obese patients had a higher prevalence and NPSI at both RT completion (21.7% and 6.9) and follow-up (16.0% and 3.6) while normal, over-weight patients showed less increase in prevalence and NPSI at RT completion (11.8% and 5.3) and recovered to the baseline levels after 1 month of RT. In summary, our data suggest that RT-related NP is associated with race/ethnicity and obesity in breast cancer patients. To improve quality of life, including NP, as an important survivorship issue for cancer patients, our ongoing biomarker studies are warranted to elucidate the molecular mechanisms and identify potential targets for intervention. Citation Format: Eunkyung Lee, Cristiane Takita, Jean L. Wright, Wei Zhao, Isildinha Reis, Omar L. Nelson, Jennifer J. Hu. Neuropathic pain in breast cancer patients undergoing radiotherapy. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4683. doi:10.1158/1538-7445.AM2014-4683