The relationship between sensory loss and persistent pain 1 year after breast cancer surgery

Moderate-to-severe persistent pain after breast cancer surgery (PPBCS) affects 10-20% of the patients. Sensory dysfunction is often concomitantly present suggesting a neuropathic pain state. The relationship between various postoperative pain states and sensory dysfunction has been examined by quantitative sensory testing (QST), but only 2 smaller studies have examined PPBCS and sensory dysfunction in the surgical area. The purpose of this prospective study was to assess the relative importance of sensory function and PPBCS. QST consisted of sensory mapping, tactile detection threshold (TDT), mechanical pain threshold (MPT) and thermal thresholds. 290 patients were enrolled and results showed that 38 (13 %) had moderate-to-severe pain and 246 (85%) had hypoesthesia in the surgical area 1 year after surgery. Increased hypoesthesia areas were associated with both pain at rest and during movement (p=0.0001). Pain during movement was associated to a side-to-side difference of 140% (p=0.001) for TDT and 40% (p=0.01) for MPT as well as increased thermal thresholds in the axilla (p˃0.001). Logistic regression models controlling for confounders demonstrated larger areas of hypoesthesia as a significant risk factor, OR 1.85 per 100 cm2 for pain at rest and OR 1.36 per 100 cm2 for pain during movement.