Would you ever start radiation in the middle of cycle 1 of chemotherapy for LS-SCLC?

The goal is to get RT started early in the course, and to maximize the concurrent part of the therapy. But of course a patient only gets chemo for a few days per cycle, and we don't know whether the ‘concurrent’ effect is entirely due to those days treatment, or whether the radio-sensitizing effect ...

Answer to question is Yes! A randomized phase III trial from Korea by Sun et al showed that thoracic radiation on cycle 3 of chemotherapy was not inferior to early radiation based on OS, PFS and RR.

https://academic.oup.com/annonc/article/24/8/2088/196699