A systematic review of opioid effects on the hypogonadal axis of cancer patients.

Purpose: Opioids are the mainstay of analgesic therapy in patients with cancer-related pain. While many of the side effects of opioids are well documented, the effect on the hypogonadal axis is less well understood. The aim of this systematic review is to examine the relationship between opioid therapy and hypogonadism in patients with cancer.
Methods: An electronic search of the following databases was undertaken: MEDLINE, Embase and CINAHL from 1974 to August 2013. To be eligible for inclusion, studies had to meet the following criteria: adult patients (>18 years) with cancer taking any opioid by any route for any duration, gonadal function measured and the relationship between opioid use and gonadal function examined. All potentially eligible papers were reviewed independently and data extracted using a pro forma.
Results: Four studies met the inclusion criteria. Due to the heterogeneous nature of the studies, it was not possible to amalgamate the results. Three studies suggested a relationship between opioid use and hypogonadism in patients with cancer. These studies also suggested this relationship to be dose dependent. There was evidence to suggest that hypogonadism was symptomatic and associated with reduced survival. One study showed no link between opioids and hypogonadism.
Conclusions: Studies conducted have suggested an association between opioids and hypogonadism in patients with cancer. This warrants further investigation. A longitudinal study examining the impact of opioids on the hypogonadal axis would be of interest.