Chronic pain, including pain caused by chemotherapeutics for cancer, is a devastating global health problem, a major unresolved healthcare issue, with tremendous socio-economic implications, particularly for long-term sufferers. For example, annual US expenditures related to pain (including direct medical costs and lost wages) are higher than those for cancer ($243 bn), heart diseases ($309 bn) and diabetes ($188 bn) combined (see Woodcock et al., 2007; Nightingale, 2012; Pizzo and Clark, 2012).