Pain response to palliative radiotherapy in bone metastases vs. non-bone lesions: Prospective study.

BACKGROUND

This study compared the pain response to palliative radiotherapy for bone metastases and non-bone lesions based on the International Consensus on Palliative Radiotherapy Effectiveness (ICPRE) criteria.

METHODS

This two-cohort study used data from a prospective cohort of 867 registered lesions from 500 patients conducted between August 2021 and September 2023. Pain responses were assessed using the ICPRE criteria at prespecified timings of 2, 4, 12, 24, 36, and 52 weeks. The primary outcome was the pain response rate within 12 weeks, comparing two groups of patients with bone and non-bone lesions. A multivariate logistic regression analysis was conducted to adjust for confounding covariates based on opioid use, irradiation history, performance status, NRS, primary disease, and radiation dose.

RESULTS

Among 678 lesions from 440 patients who met the criteria, 541 (80 %) and 137 (20 %) were in the bone and non-bone cohort, including primary tumors, lymph node metastases, and others. The mean age was 63 years, and 45 % were female. Treatment included conventional radiotherapy of a single 8 Gy dose, 20 Gy in 5 fractions, and 30 Gy in 10 fractions, used in 89 % of lesions. While opioid use (67 %) and re-irradiation rates (22 %) were not different between cohorts, the non-bone cohort had shorter median survival (4.9 months vs. 6.3 months, P = 0.017) and more frequently fractionated irradiation (85 % vs. 67 %, P < 0.001). No differences were observed in pain response rates between the two groups (57 % vs. 62 %, P = 0.33), which remained consistent after adjusting covariates. Re-irradiation and opioid were associated with negative impacts on pain response in the bone cohort. In contrast, the increased irradiation dose was identified as potentially affecting the non-bone cohort.

CONCLUSIONS

This study suggested palliative radiotherapy is effective for painful non-bone lesions and potential dose-dependency for pain response, highlighting the need for future randomized controlled trials to determine the optimal radiation dose.