Best to check with medicos before using - I thought Rogaine was primarily for female pattern baldness, not for post chemo application. Herceptin should not make your hair fall out - mine started regrowing while still on Taxol and grew steadily while on Herceptin. Didn't have radiation but can't see why it would affect regrowth. Best you can do for your ear is nurture your scalp, eat well and treat new hair very gently.