Opioid responsiveness-primary diagnosis relationship in advanced cancer patients followed at home.

The aim of this study was to evaluate the influence of the primary cancer on pain characteristics and opioid response, in terms of analgesia and adverse effects, in advanced cancer patients followed at home. A prospective study was carried out in a sample of 434 consecutive advanced cancer patients who required opioids during the last four weeks of life. One hundred eighty-one patients received opioids for longer than the four weeks and were considered for this analysis. Demographic data, primary diagnosis, and pain mechanisms were recorded, and mean opioid doses, pain intensity, and symptoms were assessed at weekly intervals during the last four weeks of life. In the group of 181 patients, somatic pain was associated with lung, head and neck, breast, and prostate cancer (p < 0.0005), while visceral pain was associated with colorectal, gastric, liver, pancreatic, and uterine cancer (p < 0.0005). Considering all primary diagnoses, there was a significant increase in the mean opioid dose (p < 0.0005) across the four weekly periods. There was a significant decrease in pain intensity scores (p < 0.0005) in all cases. A significant dose increase was observed only for mesothelioma (p = 0. 027) when compared with other types of cancer. In all 181 cases, a significant worsening in symptom intensity was observed during the last two weeks of life (p < 0.01). This study shows that primary cancer may have an influence on pain characteristics and opioid response. Patients with some kinds of cancer may be at risk of developing severe pain syndromes or more adverse effects.