455: Ninety-Day Continuous Ketamine Infusion for Refractory Cancer Pain: An Interesting Case

Topic: Clinical Science
Subtopic: Pain category (ICD-11), Chronic cancer related pain, Pharmacological treatments, Assessment and Measurement of Pain/Nociception, Treatment/management

Background and Aims: Ketamine is used as an adjuvant for refractory cancer pain, most commonly as short inpatient infusions or intermittent outpatient protocols. Reports describing prolonged continuous ketamine infusion extending for months remain limited. This case describes refractory mixed cancer-related pain managed with continuous ketamine infusion for approximately 90 days, highlighting dose titration, tolerability, and changes in patient-triggered breakthrough analgesic demand during unusually prolonged exposure. The aim of this case report was to describe the feasibility and tolerability of ultra-prolonged ketamine infusion and to explore whether sustained NMDA receptor antagonism

Methods: This case report describes a patient with refractory cancer-related mixed pain treated with continuous ketamine infusion as part of multimodal analgesia was reviewed. Ketamine infusion was initiated at 50 mg/24 hours and adjusted according to clinical response, including escalation to 100 mg/24 hours, later 250 mg/48 hours, followed by reductions and re-escalations ranging from 50–175 mg/24 hours over approximately three months. Clinical course, dose adjustments, patient-controlled analgesia (PCA) fentanyl demand patterns, and adverse-effect observations were reviewed from inpatient medical records. Concomitant opioid therapy and adjuvant analgesics were maintained throughout treatment. Serial PCA demand attempts and delivered boluses were examined as exploratory markers of breakthrough analgesic requirements during prolonged ketamine administration.

Results: Continuous ketamine infusion was maintained for approximately 90 days (June 4 to September 2). Multiple dose adjustments reflected response-guided titration in the setting of complex refractory pain. Prolonged administration was feasible, and no overt severe psychotomimetic, hemodynamic, or major ketamine-related toxicities were identified from available chart documentation. Serial PCA reviews showed a decline in breakthrough-demand attempts from as high as 51 attempts per 12 hours during earlier treatment phases to 14 attempts per 12 hours during later ketamine treatment, suggesting reduced patient-triggered PCA demand and a possible opioid-sparing signal. The infusion appeared sustainable within a multimodal analgesic regimen while balancing analgesia and evolving clinical status. The patient ultimately died from progression of underlying illness. The prolonged exposure duration, tolerability, and possible opioid-sparing signal represent an uncommon and clinically informative scenario.

Conclusions: This case highlights the feasibility of prolonged continuous ketamine infusion in a highly selected patient with refractory cancer-related pain and documents an uncommon duration of exposure seldom described in most literature that are available. It illustrates an unusual clinical course marked by sustained use, repeated titration, and a possible reduction in breakthrough analgesic demand. Its value lies primarily in the rarity of the observation and the clinical questions it raises, although any opioid-sparing signal should be interpreted cautiously in a single case.

References: Bell, R. F., Eccleston, C., & Kalso, E. A. (2017). Ketamine as an adjuvant to opioids for cancer pain. Cochrane Database of Systematic Reviews, 6, CD003351. https://doi.org/10.1002/14651858.CD003351.pub3

Cheung, K. W. A., Chan, P. C., & Lo, S. H. (2020). The use of ketamine in the management of refractory cancer pain in a palliative care unit. Annals of Palliative Medicine, 9(6), 3950–3961. https://doi.org/10.21037/apm.2019.09.09

Hardy, J., Quinn, S., Fazekas, B., Plummer, J., Eckermann, S., Agar, M., ... Currow, D. C. (2012). Randomized, double-blind, placebo-controlled study to assess the efficacy and toxicity of subcutaneous ketamine in the management of cancer pain. Journal of Clinical Oncology, 30(29), 3611–3617.

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Presenting Author: Dr. Tiffany Joy Chavez
Submitting Author: Tiffany Joy Chavez

Senior Author: Dr. Luzviminda S. Kwong

IASP 2026 Global Year theme of Neuropathic Pain: No