my limited reply to the Treatment proposal:
(here)
https://drive.google.com/file/d/1SnWBLpWh0uHgghgi-opHmOgbrEpLrB79/view
I think the treatment table is a reasonable construct to add.
Targeting MEASUREMENT table for data from cancer registry is also good approach.
See slide 25 here:
http://www.ohdsi.org/web/wiki/lib/exe/fetch.php?media=documentation:oncology:cancer_diagnostic_features_2018-02-07.pptx