Advanced cancer pain: the search for genetic factors correlated with interindividual variability in opioid requirement

To assess association between genetic variants and opioid requirement in cancer patients. A prospective observational trial of 243 advanced cancer patients with inadequate analgesia treated by the palliative care team was analyzed for and polymorphisms. For patients carrying 118AG/GG and 472GG (Val158Val) or these genotypes alone, a significant higher median percentage dose increase was observed (95.2% [32.8-345]) compared with 118AA and 472GA/AA (158M allele carriers; 48.5% [0-98.8]; p = 0.0016). No associations were found with morphine equivalent dose after consultation palliative care team or ketamine use. Patients with the combined 118AG/GG and genotype required 50% higher dose increase for sufficient analgesia.