Inconsistencies in assessment of pain endpoints in radiotherapy for painful tumors: Analysis of original articles in the Green and Red Journals

Treatment outcomes of radiotherapy for malignant psoas syndrome: A single-center retrospective study

INTRODUCTION

The efficacy of radiotherapy for symptomatic relief of malignant psoas syndrome (MPS) remains unknown because there are limited publications with high level evidence, including analyses with sufficient number of cases, clinical trials, and systematic reviews about radiotherapy for MPS. We aimed to investigate the characteristics of and symptom relief rates in patients treated with radiotherapy for MPS in palliative intent.

METHODS

In this single-center retrospective study, we analyzed data of 22 consecutive patients treated with radiotherapy for MPS at our institution in Japan between 2012 and 2022. We recorded patient characteristics, including primary site, invasion pattern, recognition of MPS by the attending physician, radiation regimen, biological effective dose with α/β = 10 Gy (BED10), and adverse events. Since no objective evaluation index for palliative radiotherapy for non-bone metastases has been established, we modified and used an International Consensus on Palliative Radiotherapy Endpoint, which was originally used for bone metastases, to evaluate symptom relief in the present retrospective study. "Response" was defined as symptom relief described in medical records or the use of analgesic medications reduced by ≥25% within 3 months post-initiation of radiotherapy.

RESULTS

Genitourinary organs (41%) were the most common primary-tumor sites. MPS was caused by metastasis in the iliopsoas muscle in 14 patients (64%) and by direct invasion of the primary tumor in eight patients (36%). Since the optimal radiation dose for MPS has not been established, the radiation dose varied from low dose, which are used in palliative radiotherapy for painful bone metastases, to high dose with conventional fraction using 1.8 to 2 Gy per fraction, with a median BED10 of 48 Gy (range, 10.6-79.2 Gy). Fifteen patients (68%) achieved a response. No acute nor late adverse events of grade 2 or higher, according to Common Terminology Criteria for Adverse Events version 5.0, were reported during the observation period.

CONCLUSION

Radiotherapy for symptomatic MPS might be an effective treatment option with a high response rate (68%) and minimal adverse events. Since the present study is a retrospective study with small number of cases, a prospective study with a larger sample size is required.

Radiation Therapy for Painful Bone Metastases: Fractionation, Recalcification, and Symptom Control

Bone is a common site for metastases, which may cause pain and other skeletal-related events (SRE) in patients with advanced cancer. Since the 1980s, prospective clinical trials have demonstrated the high efficacy of external beam radiotherapy (EBRT) for pain relief from focal, symptomatic lesions. In uncomplicated bone metastases, which include those without pathologic fracture, evidence of cord compression, or prior surgical intervention, improvement or complete pain relief with radiotherapy is as high as 60%, with no difference in efficacy when radiotherapy is delivered in a single or multiple fractions. The ability to treat with a single fraction makes EBRT an attractive therapy even for patients with poor performance status and/or life expectancy. Even in patients with complicated bone metastases (eg cord compression), several randomized trials have demonstrated similar rates of pain relief in addition to improved functional outcomes such as ambulation. In this review, we summarize the role of EBRT for alleviating painful bone metastases and explore its role for other endpoints including functional outcomes, recalcification, and prevention of SREs.

Pain Response Rates After Conventional Radiation Therapy for Bone Metastases Assessed Using International Consensus Pain Response Endpoints: A Systematic Review and Meta-Analysis of Initial Radiation Therapy and Reirradiation

Previous meta-analysis of conventional radiation therapy for painful bone metastases showed overall response (OR) rates of 72% to 75% (evaluable patients), 61% to 62% (intent-to-treat patients) for initial radiation therapy, and 68% for reirradiation (evaluable patients). However, the definition of pain response differed among the studies included. Hence, we conducted a systematic review and meta-analysis to determine the pain response rates assessed by the International Consensus Pain Response Endpoints (ICPRE) for both initial radiation therapy and reirradiation. The PubMed and Scopus databases were searched for articles published between 2002 and 2021. The inclusion criteria were (1) prospective studies or studies based on prospectively collected data and (2) studies in which pain response was assessed using ICPRE. Our primary outcomes of interest were the OR rates (sum of the complete and partial response rates) for both initial radiation therapy and reirradiation. Of the 6470 articles identified in our database search, 32 and 3 met the inclusion criteria for the analysis of initial radiation therapy and reirradiation, respectively. The OR rates of initial radiation therapy in evaluable patients (n = 4775) and intent-to-treat patients (n = 6775) were 60.4% (95% confidence interval [CI], 55.2-65.4) and 45.4% (95% CI, 38.7-52.4), respectively. The OR rates of reirradiation in evaluable patients (n = 733) and intent-to-treat patients (n = 1085) were 70.8% (95% CI, 15.7-96.9) and 62.2% (95% CI, 5.3-98.0), respectively. Subgroup analyses of initial radiation therapy including the comparison of randomized and nonrandomized studies showed no significant differences in any comparison, indicating similar response rates across different study designs. For initial radiation therapy, we determined the ICPRE-assessed response rates, which were lower than previously reported. The OR and complete response rates should be benchmarks for future randomized and nonrandomized studies. For reirradiation, the wide CIs demonstrate that the response rates based on ICPRE require further investigation.

Palliative radiotherapy for painful lymph node metastases

BACKGROUND

There is limited evidence concerning radiotherapy for painful lymph node metastases (PLM). We evaluated the effectiveness of radiotherapy for PLM using the International Consensus Endpoint in a subgroup analysis of a prospective observational study.

METHODS

In the primary study, 302 patients received radiotherapy for painful tumors. Among them, those treated with palliative radiotherapy for PLM were analyzed in the present study. We used the Brief Pain Inventory short form to evaluate the intensity of pain and the pain interference in patient's life. We collected the Brief Pain Inventory and analgesic data at baseline and at 1, 2, and 3 months after the start of radiotherapy. Pain response was assessed using the International Consensus Endpoint. Patients were diagnosed with a predominance of other pain (POP) if non-index pain of a malignant or unknown origin was present and had a greater 'worst pain' score than the index pain.

RESULTS

Radiotherapy for PLM was performed on 25 patients. In total, 15 (60%) patients experienced a pain response. The pain response rates for evaluable patients were 66%, 67%, and 57% at 1-, 2-, and 3-month follow-ups, respectively. At baseline and at 1, 2, and 3 months, the median index pain scores were 7, 2, 0, and 0.5, respectively. At 1 month, all pain interference scores were significantly reduced from baseline. Four (16%) patients experienced POP within three months.

CONCLUSION

Radiotherapy for PLM improved pain intensity and pain interference. Palliative radiotherapy may be a viable treatment option for PLM.