Zhi Cheng, Radiation Oncology
Effective Pain Management with Prophylactic Gabapentin in the Irradiated Head and Neck Cancer Patient is Associated with Functional Benefits.
Harry Quon1,2, Zhi Cheng1, Heather Starmer2, Scott Robertson1, Wuyang Yang1, Marian Richardson1, Mysha Allen1, Sarah Afonso1, Marissa Stoltzfus2, Giuseppe Sanguineti1, Anna Ponce Kiess1, Christine Gourin2, Todd McNutt1
Department of Radiation Oncology and Molecular Radiation Sciences, Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University
Background: The efficacy of radiotherapy for head and neck cancers can be limited by mucositis and the secondary pain resulting in treatment interruptions and functional impairments due to dysphagia. Dysphagia can contribute to post-treatment disuse atrophy of the swallow muscles. We hypothesize that prophylactic gabapentin through a novel mechanism of action may improve pain control and have potential secondary benefits.
Methods: Retrospective query and analysis of prospectively acquired structured data elements (SDEs) during routine clinical care held in an integrated dosimetric and clinical database (Oncospace) was undertaken. Eligibility included a diagnosis of head and neck cancer treated with definitive radiotherapy +/- concurrent chemotherapy +/- induction chemotherapy. Patients were grouped based on pain management strategies: routine use of narcotics reactive to pain (group 1), prophylactic gabapentin with narcotics as needed (group 2), and prophylactic gabapentin with prophylactic low-dose narcotics titrated to effect (group3). Descriptive statistics and ANOVA, Tukey and Chi-square tests (SAS v9.3) were used to compare pain scores, treatment duration, weight loss, equivalent oxycodone use during treatment, physiologic swallowing outcomes by Penetration Aspiration Scores (PAS) and diet level by Functional Oral Intake Scale (FOIS) scores following completion of treatment.
Results: 521 patients treated between 10/2007 and 1/2014 were identified. Group 2 and 3 received a higher total dose with more treated with hyperfractionated RT and concurrent chemotherapy compared to group 1 (<.0001). Despite this, prophylactic gabapentin (groups 2 and 3) improved mean and maximum pain scores compared to group 1 (p<0.0001). The gabapentin groups also demonstrated fewer treatment interruptions (p<0.0001) and less weight loss (p<0.0285). Amongst the gabapentin groups, prophylactic narcotics (group 3) resulted in non-significant trends towards lower pain scores, fewer treatment interruptions, less weight loss and less equivalent oxycodone use than patients receiving narcotics as needed (group 2). Prophylatic gabapentin also improved post-treatment PAS (p=0.001) and FOIS scores (p<0.0001) compared to narcotics alone (group 1). Amongst the gabapentin groups, prophylactic narcotics (group 3) provided non-significant trends improving both the mean PAS scores compared to group 2. Conclusions: Systematic capture of SDEs from Oncospace facilitates large data analysis of the impact of systematic changes in practice patterns. Gabapentin for mucositis pain is effective and associated with less weight loss, fewer RT treatment interruptions and a higher probability of maintaining an oral diet and normal swallow function. Post-treatment swallow function appears to be improved. Randomized evaluation of prophylactic gabapentin is indicated.