This probably underlies some tumor responses that extend beyond the radiation field, as in the case series by Xu et al. These authors reported the impressive outcomes of two patients with mMCC progressing on PD-1 inhibitor therapy and then treated with 8 Gy-single-fraction palliative radiotherapy to some portion of the tumor masses: surprisingly, both patients rapidly experienced a marked reduction until disappearance not only of the irradiated tumor portion, but also of the distant out-of-field tumor sites [45]. The gene discussed is PDCD1; the disease is neoplasm.