ESTRO 2024 - Abstract Book
S2018
Clinical - Paediatric
ESTRO 2024
CED. For procarbazine dose, risk increased with increasing dose with an IRR of 6.3 (95%CI 3.0-13.2) for doses 4.2 7.0g/m 2 and an IRR of 9.0 (95%CI 4.3-18.9) for doses ≥7.0g/m 2 .
For treatment interactions ( Table 1 ), increased risk was observed for survivors who received both (or either) abdominopelvic RT and chemotherapy compared with those who received neither; this effect was observed across all models using yes/no exposure data or ordinal categorical dose bins. The highest risk with an IRR of 22.7 (95%CI 10.6-48.8) was observed for survivors who received mean colorectal doses ≥10Gy and procarbazine doses >4.2 mg/m 2 .
Conclusion:
We quantified the RT dose and dose-volume effect for colorectal SMN in a cohort of childhood cancer survivors. A dose-volume effect was observed for V5, V10, V20, V30 and V40 with risk increasing with increasing volume for irradiated volumes >20%. For survivors who received colorectal mean RT dose ≥10Gy, colorectal SMN risk increased with increasing dose. We also identified a strong interaction relationship between colorectum RT dose and chemotherapy, with the highest risk observed for survivors who received mean colorectal doses ≥10Gy and procarbazine doses >4.0 mg/m 2 . To our knowledge, this is the largest childhood cancer survivor cohort study to examine colorectal SMN risk associations with organ-specific RT dose-volume metrics to the total colorectum, substructure-specific mean RT doses, and alkylating dose (as alkylating cumulative dose and procarbazine-specific cumulative dose).
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