Analgesic response, incidental pain and pain mechanism were evaluated in order to predict the chances of pain relief in advanced cancer patients. In an observation period of about 2 months, 130 patients were followed at home until death using only a pharmacological approach to control pain according to the WHO ladders. Ninety-eight patients were considered. Pain relief was considered good if less than moderate. Pain was assessed during the course of examinations (2-3 a week) by independent observers. If other techniques were needed the result was considered negative. The patients were tested with an NSAID (Diclofenac) and assigned to group 1 if the pain became slight in 3 days. If the response was negative, a 4-day trial with opioids was started. If the pain was slight the patient was included in group 3, otherwise in group 5. Every patient belonging to these groups but with incidentical pain was included in groups 2, 4 and 6, respectively. For each group a subdivision was made according to the pain characteristics. There was a progressive worsening in pain relief in groups 4, 5 and 6, suggesting a good correlation between response to the drugs and future chances of pain control in a period of 2 months. This study demonstrates that incidental pain reduces the possibility of pain control (50%) with the exclusive administration of analgesics in patients with a mean life expectation of about 2 months. This negative influence is counterbalanced by the possible individual response to analgesics administered sequentially during a 1-week period (85.8% good pain relief with NSAID, 74% with opioids).(ABSTRACT TRUNCATED AT 250 WORDS)
