Characterization of cancer-induced bone pain: an exploratory study

Cancer-induced bone pain (CIBP) is the commonest cause of pain in patients with cancer. Its association with increased morbidity combined with limitations of currently available therapies makes it a clinical challenge. Clinical characterization of this complex pain syndrome is essential in underpinning clinical management and informing future research. The aim of this exploratory study was to characterise CIBP using self-rating scales.

A cross-sectional survey of patients with CIBP was carried out in a regional oncology centre. Patients described their pain over the preceding 24 h using the McGill Pain Questionnaire, Brief Pain Inventory (BPI), and a breakthrough pain questionnaire. Multiple linear regression analyses were conducted.

Fifty-five patients were recruited. Annoying, gnawing, aching, and nagging were the most commonly used words to describe CIBP. From the BPI, median average pain was 4/10 and worst pain was 7/10 on a 0-10 Numerical Rating Scale. The worst pain score correlated more strongly with BPI interference score (p=0.001). Forty-one patients had breakthrough pain. Patients with breakthrough pain had higher total BPI interference scores than those with no breakthrough pain; median (IQR); 35.0 (2.5-44.7) vs. 18.5 (5.5-26.7), p<0.01. Of the patients, 20/41 (48%) had breakthrough pain of rapid onset (less than 5 min) and short duration (less than 15 min).

In CIBP, worst pain most accurately reflects the characteristics of pain flares and functional impairment. Breakthrough pain is often unpredictable, sudden onset and short duration. Further characterization studies of CIBP in the broader cancer population are needed.