I can share my experience with this . Last winter I did a bulk cycle . Test e , deca and proviron . I was experimenting with the whole no AI or at least minimum AI . I was trying to let my estrogen run slightly elevated . Many think that interfering with aromatization will inhibit gains to some degree . So I was on a gram of test , 100mg provi /day and 600mg/wk deca . I took 12.5 mg/e3d of aromasin , a minimal amount . Now I have never had even an itchy nipple much less any swelling or lumps . At about 4 weeks my left nipple had swelling around the nipple , quite pronounced . So the proviron didn't do the job completely . I upped the sin to 12.5 mg eod , kept the provi at 100mg/day and all was well after . For me the provi helped control estrogen but I did need some dose of AI on a large dose cycle . I do not have labs to prove this other than the visual results , my bad .