A Study of Reduced-dose Radiation in People With Metastatic Tumors With a Genetic Change

Inclusion Criteria: * Histologically confirmed malignancy with at least one metastatic lesion referred for palliative radiotherapy * Pathogenic mutation in ATM (somatic and germline allowed) * ECOG performance status 0-2 * Age ≥ 18 years. * Able to provide informed consent. * Patients at reproductive potential must agree to practice an effective contraceptive method during radiation treatments. * Expected life expectancy of at least 6 months Exclusion Criteria: * Previous radiotherapy to the intended treatment site that precludes developing a treatment plan that respects normal tissue tolerances. * Serious medical co-morbidities precluding radiotherapy. * Pregnant or breast-feeding women. * Lesions excluded from de-escalation include regions in which the risk of local disease progression is unacceptably high, including CNS disease and cord compression, and areas in which re-irradiation would not be feasible, including spinal cord overlap.