[Chronic refractory pain in cancer patients. Value of the spinal injection of lysine acetylsalicylate. 60 cases].

Several animal studies have demonstrated that pain is modulated by spinal mechanisms involving prostaglandins and that acetylsalicylic acid (ASA) administered intrathecally has an analgesic effect. We report our experience of this treatment in 60 patients with proven and advanced cancer. An isobaric solution of lysine acetylsalicylate was administered by lumbar puncture in doses ranging from 120 to 720 mg of ASA. The results were evaluated using the habitual criteria: scoring system, behaviour, consumption of analgesic drugs. In this trial the method proved astonishingly effective (78% of the cases). Analgesia was strong, almost immediate and without influence on motricity. No thermic or neurovegetative changes were noted. The effect of one injection lasted from 3 weeks to 1 month on average; it was reproduced and often more prolonged after a repeat injection. Pain associated with bone metastases seems to constitute the best indication, notably in breast and lung cancer and in myeloma. Visceral (pancreas) or neural pain requires higher doses to respond. Failures (22%) were due to such factors as insufficient dosage at the very beginning of our experience or severe depressive syndrome. The perineal and sphincteral pain of rectal cancer often resists treatment. This simple, inexpensive and very effective method with no other complication than a frequent tendency to fatigue should rank among other analgesic measures in cancer. The lack of respiratory depression is a major advantage over catheter spinal opiate analgesia. We consider that its main indications are pain associated with osteolytic metastases of adenocarcinomas, and myelomas. Owing to the absence of formal toxicological data, its use must be limited to cancer pain and to patients with a life expectancy of less than 2 years.