ALERT:
timely brain mets discussion here. "Perhaps the largest question is how the improvements in targeted and immunologic therapies for NSCLC will affect the natural history of CNS disease." I can reasonably and likely predict that targeted/immunologic therapy effectiveness and metachronous CNS progression are inversely correlated; I can also further reasonably and likely predict that targeted/immunologic therapies are increasing in effectiveness over time.
These sentences makes zero sense to me. Am I the only one?
"What then should we make of the success of deferred SRS in this trial? Of the patients randomly assigned to SRS, approximately one sixth needed more than one course of SRS, and more than one third required WBRT, implying that in a large proportion of patients, delayed SRS at time of salvage does not work as well as desired, given that in the definitive setting, it produces > 90% local control"
When you SRS a lesion you usually have to SRS them again (at some point) because of distant brain failure. That is inherent whether it is salvage or post-op SRS. The issue is not local recurrence.
It's the same question as is in post-prostatectomy prostate cancer - is there a difference between adjuvant and early salvage.
In post-op brain mets, is there a difference in local progression between observation and adjuvant? Yes, as expected, given the Mahajan trial results. However, is there a difference in survival between observation (and early salvage as necessary) and adjuvant? No, per the Mahajan paper again (although it's not powered to look at OS, the median OS was 18 and 17 months for the two groups).
Should we routinely be post-op WBRTing? I'd argue not if they're otherwise candidates for SRS. That's what the trial (for which the above article is an editorial) is essentially saying (
http://ascopubs.org/doi/full/10.1200/JCO.2018.78.6186). Japan runs SRS trials with weird comparative arms, IMO.
I would probably still favor post-op SRS for the local recurrence prevention (like in Mahajan) but salvage SRS is an option as well. Clinically, it's driven if I'm doing SRS at that moment in time anyways (for definitive lesions) - if I'm in there anyways I'd rather just radiate the post-op cavity too. Arguably, if it was a solitary brain met I'd want to radiate that. If it's one brain met but extensive extracranial disease then maybe I can have a discussion with the patient about treating now vs at salvage.