For T cell ALL treated in CR (without transplant), how often do you do BM biopsies as part of surveillance, and for how long?

The role of surveillance bone marrow exams in ALL (either B or T-lineage) is a matter of some debate. Thoughtful clinicians can disagree, but in my practice, I do NOT routinely perform these procedures, instead reserving them for signs or symptoms suspicious for relapse. This is analogous to how the practice has shifted in patients with aggressive lymphomas, where the use of surveillance CT scans has been shown to be unhelpful [Thompson et al., PMID 25267745].

First, the point of surveillance bone marrow exams is generally to attempt to "catch relapse early." While there are certain advantages that could occur in this scenario, there are no data to my knowledge that actually support this assertion. It is tempting to assume that using blinatu...