Opioid therapy and tumor progression

Michael Schäfer; Shaaban A. Mousa

Vol 8, No 2 (2009)

Review articles

Published online: 2009-03-30

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Opioid therapy and tumor progression

Michael Schäfer, Shaaban A. Mousa

Advances in Palliative Medicine 2009;8(2):53-56.

Vol 8, No 2 (2009)

Review articles

Published online: 2009-03-30

Abstract

It is well established that opioids help the organism to cope with environmental stress, tissue injury, pathogen invasion, inflammation, and tumor growth. Opioids elicit immunosupressive effects which may become benefitial in the context of chronic inflammation, however, it may be detremental in the context of tissue repair. These direct immunosuppressive effects of opioids would possibly facilitate tumor growth, however, in the context of pain and distress, which is known to promote tumor progression by a reduction in NK cell cytotoxicity, opioids clearly show a beneficial effect in reducing local tumor growth as well as dissemination of metastases. Recently, growing evidence accumulates that tumor cells express both opioid receptors and their ligands, the opioid peptides, suggesting that opioids may also directly affect tumor progression. Metenkephalin seems to play a most prominent role possibly acting via a different receptor than the classical opioid receptor. However, there is still great need for further studies to corroborate these interesting findings.