Opioids are the gold standard for the management of moderate to severe cancer pain. The clinical use of opioids is limited because of co-morbidities associated with extended use. The goal of Dr. Roy’s studies is to identify therapeutic targets that can prolong opioid use and minimize its co-morbidities. Their recent studies show an association between chronic opioid use and altered gut microbiome. These findings have strong implications that manipulating the gut microbiome can be a potential therapeutic target to improve the pain relieving efficacy of opioids.