Reirradiation Dose Escalation in Thoracic Cancers

This is a study involving patients with recurrence, metastasis, or new primary malignancies in the thorax requiring radiation and who have previously received radiotherapy to the thorax, where re-irradiation is expected to exceed the dose constraints used for de novo treatments. Currently, when this group of patients needs another set of radiotherapy, there is a dose limitation based on a percentage of the previous treatment's dose. However, this dose often limits the effectiveness of repeated treatment, with little scientific support for such. Therefore, this study aims to determine the maximally tolerated dose of reirradiation in the thorax, with dose escalation implemented by sequentially increasing the normal tissue recovery factors (i.e. repair factors) to the previously delivered dose. Using a recovery factor equation associated with a 35% or lower rate of grade 3-5 treatment-related toxicity occurring within 1 year of treatment, accrual will start at level 1 (recovery factor = 10% at 6 months + 0.75% per month thereafter). Patients will be assigned to recovery factors using the TITE-CRM model. The model will use all available information from previously accrued patients to assign the highest dose with a predicted risk of grade 3-5 toxicity of 35% or less.