Do you offer systemic therapy for NSCLC (no driver mutation) after resection of a metachronous solitary brain metastasis occuring after definitive therapy for limited disease, with no evidence of active extracranial disease?

I'm not sure that I have any definitive evidence to present regarding this (ie no trial data), speaking primarily from experience and bias. As I take it, the patient presented in the question is now surgically NED and has had appropriate treatment of his isolated metastatic site of disease with no known disease below the neck. I generally do not treat with systemic therapy, acknowledging that this patient has a high risk for relapse (both within and outside of the CNS), I follow them closely (every two or three months) with the intent to intervene (ie start systemic therapy) upon evidence of progression. The counterargument (for which I can offer no contradiction) is that this is analogous to adjuvant therapy for which we have definitive be...

I agree with @Dr. First Last's rationale and logic. This patient's greatest risk is for over-treatment (Dr. Otterson's #1 rationale above) and, in the setting of definite metastatic disease, I cannot rationalize exposing the patient to risk for, at best, uncertain benefit. Many patients, of course, will jump at the chance for chemotherapy, incorrectly thinking they have an enhanced chance for cure. Consider that in true localized situations, in other words, the best of circumstances, adjuvant therapy with 4 cycles of platinum doublet confers an absolute risk reduction of 5%, meaning a NNT of 20 to cure/save 1 life. In this case, we must acknowledge the recurrence risk is much higher than any surgically resected stage I-III patient. Thus, th...