Low dose test is completely fine but running hardcore stacks should be avoided if it effects your health markers (bp/pulse/rbc).. I have been in for surgery twice last year and have been on test/tren/mast stacks, not high doses but I'm young and monitor my health closely and my health markers are mostly unchanged.. It really just depends if you are prone to bp/rbc changes due to gear. It doesn't really make any sense to start a blast before surgery mind you.. I had been on for a couple months when my surgeries came up so I was just continuing them so I didn't have go waste my time with the hormones lowering in my blood and then building them back up post surgery.