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Letter to Editor: Transcutaneous electrical nerve stimulation (TENS) for cancer bone pain

Painful bone metastases remain the most common cause of cancer-related pain and are associated with a significantly reduced quality of life.1,2 Cancer bone pain can often be both severe and difficult to treat.3,4 Less than half of all patients with cancer bone pain experience significant relief of their pain with current treatments.5–7 Transcutaneous electrical nerve stimulation (TENS) is used throughout the world to manage painful conditions because it is inexpensive, non-invasive, safe and is simple to use. However, a recent Cochrane systematic review of TENS in cancer pain found insufficient evidence to make decisions on the use of TENS in this setting.8 We report the results of a small pilot study designed to assess the acceptability of TENS as an analgesic intervention in patients with cancer bone pain and assess the suitability of measuring any analgesic benefits using both uni and multidimensional pain scores. The information gathered has been used to design a randomised, controlled clinical trial. Following ethics committee approval, we prospectively recruited seven patients with cancer bone pain from St Gemma’s Hospice, Leeds, UK. Short-form McGill, Numerical Rating Scale (NRS), Verbal Rating Scale (VRS) and Visual Analogue Score (VAS) were completed at rest and during a movement which the patient found painful (either standing, walking, bending or putting on a shirt). After completing baseline pain scores, TENS was applied to the site of bone pain using an Ultima XL-A1 device (TensCare LTD, Epsom UK). A single channel with two self-adhering gel pads was used to achieve paraesthesia over the site of pain. The TENS device was adjusted to deliver a pulse width of 200 μs and a pulse frequency of 80 Hz. Intensity was increased until the sensation from TENS was ‘strong but comfortable’. After 30 min and 1 h, measurements of pain intensity and pain relief were completed at rest and while performing the painful movement. Six patients completed the TENS treatment and pain assessments. They all showed improvement in pain scores at rest and during painful movement at 30 and 60 min of TENS (Table 1). One of the six patients who completed the study reported increased lower back pain 24 h after TENS therapy to this area. Although the pain was attributed to a prolapsed lumbar disc, we cannot discount the possibility that this may have been exacerbated by the TENS application. The analgesic effects of the TENS device allowed patients to increase the range of their normally painful movement (in this case bending over) which could lead