REVIEW   Free access

Minerva Anestesiologica 2021 February;87(2):210-22

DOI: 10.23736/S0375-9393.20.14822-3

Copyright © 2020 EDIZIONI MINERVA MEDICA

lingua: Inglese

Chronic cancer and non-cancer pain and opioid-induced hyperalgesia share common mechanisms: neuroinflammation and central sensitization

Angela SANTONI ^{1, 2}, Sebastiano MERCADANTE ³, Edoardo ARCURI ^{4, 5} ✉

¹ Department of Molecular Medicine, Laboratory affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza University, Rome, Italy; ² IRCCS Neuromed, Pozzilli, Isernia, Italy; ³ Main Regional Center of Supportive/Palliative Care, La Maddalena Cancer Center, Palermo, Italy; ⁴ IRCCS Regina Elena Cancer Institute, IFO, Rome, Italy; ⁵ Ars Medica Pain Clinic, Rome, Italy

Neuroinflammation, a peculiar form of inflammation that occurs in response to noxious stimuli in peripheral and central nervous system (CNS), consists in altered vascular permeability followed by leukocyte recruitment and activation in the inflamed tissue, release of inflammatory mediators including cytokines and chemokines, and finally in the activation of microglia and astrocytes in the spinal cord and CNS. This phenomenon mediates and even worsen the inflammatory pain in many painful states and is responsible for central sensitization leading to pain chronicity. We describe the major neuroinflammatory mechanisms shared by cancer and non-cancer pain. Particular attention is given to two different chronic inflammatory painful diseases such as the complex regional pain syndrome and the rheumatoid arthritis as prototypes of neuroinflammatory diseases (gliopathies). In addition, we describe the complexity of tumor microenvironment, their main cellular components (tumor cells, tumor infiltrating leukocytes and sensory neurons) and their reciprocal interactions that characterize different forms and intensity of cancer pain. We also hypothesize that one type of cancer pain, the breakthrough pain, can be attributable to receptor-mediated interaction of opioids with tumor cells and intratumoral leukocytes. Surprisingly, long-term opioid treatment shares the same neuroinflammatory potential responsible for the chronicity of both cancer and non-cancer pain; thus, resulting in paradoxical worsening rather than relieving pain. This paradox has upset the world of pain therapy, with neuroinflammation now being a main target of emerging therapies.

KEY WORDS: Chronic pain; Cancer pain; Hyperalgesia; Opioid epidemic