A brief account is first given of the incidence and characteristics of cancer pain. The management of such pain should involve treatment of the malignant condition, psychological support, pharmacological supplementation and interruption of the pain pathways. The paper proceeds to detail the various methods by which this last objective can be achieved. The most widely applicable method is intrathecal injection of a neurolytic agent-phenol, chlorocresol or alcohol. This will provide 2-4 months relief in about 60 per cent patients. More prolonged and extensive relief can be done by cordotomy; the percutaneous procedure has the advantages of involving no general anaesthesia and only brief hospitalisation. For patients with hormone dependent tumours and those with widespread pain, relief can be obtained by destruction of the pituitary gland with absolute alcohol. The injection is carried out through a needle inserted into the gland via the nose and sphenoid sinus; one or two repeat injections may be necessary. When pain is partly due to involvement of autonomic nerves, it is necessary to carry out appropriate autonomic neurolysis, e.g. coeliac plexus block for visceral pain. Finally, the paper deals with non-invasive pain relief techniques, especially dorsal column and central nerve stimulation.

The spinothalamic tract (STT) is a major ascending nociceptive pathway, interruption of which by cordotomy is used for pain relief, whereas the dorsal column (DC) pathway is usually not considered to be involved in pain transmission. However, recent clinical studies showed good relief of visceral pain in cancer patients after a DC lesion. Electrophysiological recordings in animals suggest that the analgesic effect is due to interruption of axons ascending from postsynaptic dorsal column (PSDC) neurons located in the vicinity of the central canal. In this behavioral study, we used a decrease in exploratory activity in rats after a noxious stimulus as an indicator of perceived pain, independent of withdrawal reflexes. Intradermal capsaicin injection almost abolished exploratory activity in naïve animals or in rats after a DC lesion, but did not change it in rats after ipsilateral dorsal rhizotomy or a lesion of the lateral funiculus on the side opposite to the injection. In contrast, a bilateral DC lesion counteracted the decrease in exploratory activity induced by noxious visceral stimuli for at least 180 days after the surgery. Although neurons projecting in both the STT and the PSDC path can be activated by noxious stimuli of cutaneous or visceral origin, our results suggest that the STT plays a crucial role in the perception of acute cutaneous pain and that the DC pathway is important for transmission of visceral pain.