The purpose of work package 5 is to identify: 1) risk factors 2) incidence 3) mechanisms of chronic postsurgical pain using groin hernia repair, breast cancer surgery and thoracotomy as clinical models. The studies have so far shown that persistent pain after these operations is an important clinical problem, that there may be a potential for reduction of these complaints after minimal invasive surgery, that quantitative sensory testing may be helpful to characterise these patients. However, more work is required on the reproducibility of quantitative sensory testing in such patients, especially comparing pre- and postoperative assessments. Validated new assessment scores on the functional consequences of persistent postsurgical pain are under evaluation in breast cancer and thoracic surgery, but not in hernia surgery, since they are already available in the literature. A specific emphasis is been made on the mechanisms of oxaliplatin and docetaxel -induced neuropathies after rectal and breast cancer surgery, respectively. Detailed studies on the neurophysiological mechanisms of short and longterm pain and the possibility for sub-grouping patients and allocation to a mechanism-based treatment. Ongoing prospective studies will focus to identify pathogenic factors including preoperative neurophysiological measures involved in persistent postsurgical pain. A specific focus is paid on the role of surgical treatment with neurectomy and mesh removal in patients with severe pain complaints after previous groin hernia repair and where long-term benefits seem to be achieved.
A series of collaborations with other work packages are either ongoing or underway: 1) WP 5.2/5.3 and WP 3.1 on cold hyperalgesia, 2) WP5.2/5.3 and WP 4.6-8 on QST training, sensory profiling and questionnaires; 3) WP 5.2/5.3/5.7 and WP 3.2 and WP 1 on capsaicin and UVB induced hyperalgesia and genes; 4) WP 5.3 and WP4.1 on placebo effects in hyperalgesia and allodynia.