How would you approach treatment for patients with limited stage small cell lung cancer who, after initial carboplatin/etoposide, develop a new contralateral lung nodule confirmed as SCLC, while their primary tumor shows a partial response?

I assume the scenario is a newly diagnosed LS SCLC in a patient who was appropriately staged with PETCT, brain MRI, etc at time of initial diagnosis. Patient is then treated with definitive chemorads with 4 cycles of platinum/etoposide and xrt. At the time of re staging PETCT, a new contralateral nodule not previously present is noted. Bx showed SCLC. Overall, I would consider this to be an unusual scenario. I am not sure that there is one right answer. I would discuss patient in tumor board. if...

Since the primary tumor shows only a partial response, I would approach this as relapsed disease, especially if the new lesion develops soon after completion of chemoradiation and while on maintenance durvalumab. If, on the other hand, there has been a long interval between completion of chemoradiation and durvalumab, this could be treated as a solitary metastases/new primary and treated with local therapy, and hold the next line of systemic therapy.