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Previous pain response strongly predicted benefit from palliative reirradiation

Pain response after reirradiation was 60% in lesions that previously responded to RT versus 15% after primary nonresponse.

RadOncToday · ·1 min read

KEY POINTS

  • This lesion-level analysis used a prospectively maintained cohort following patients from initial palliative RT through reirradiation. The reirradiation cohort included 148 patients with 214 painful lesions, with standardized pain and analgesic assessments after both courses.
  • At repeat treatment, median pain score was 7/10, 77% of patients were receiving opioids and 69% of lesions received 8 Gy in a single fraction. Median interval between RT courses was 6.1 months.
  • Overall, 93/214 lesions (43%) achieved a pain response within 12 weeks after reirradiation according to International Consensus Pain Response Endpoints.
  • Response depended strongly on what happened after the first course. Lesions that had previously responded and later became painful again responded to reirradiation in 60.0% of cases versus only 15.2% among lesions that had never responded to initial RT.
  • The association remained strong after adjustment for opioid use, pain intensity, performance status, tumor radiosensitivity, treatment interval, lesion site and dose: previous responders had 8.56-fold higher odds of response. Adjusted predicted response probabilities were 59.8% versus 17.9%, an absolute difference of 41.9 percentage points.
  • Radiosensitive histology independently increased the probability of response, whereas opioid use and baseline pain score ≥7 were associated with lower response. Fractionation schedule, interval between courses and performance status were not independently significant.
  • Reirradiation toxicity was generally limited to grade 1–2 events, predominantly nausea/vomiting and pain flare. There was one grade 3 pain flare, with no attributable spinal cord compression or cauda equina syndrome.

CLINICAL TAKEAWAY

When deciding whether to reirradiate a painful lesion, the response to the first course may be one of the most clinically useful pieces of information available. Pain that recurs after an initial response appears very different from pain that was truly radiation-refractory from the start, although these observational data should inform expectations rather than determine treatment eligibility alone.

SOURCE

International Journal of Radiation Oncology, Biology, Physics

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