I've recently had my first cycle of adjuvant chemo for breast cancer. I had a mastectomy with clear margins but my onco score came back at 40. Was recommended chemo and I agreed. 
I however have a history of Bipolar - which has been under control for many years but I had quite a bad reaction to the Dexamethasone. This has frightened the life out of me and I would never agreed to take this stuff had I known it would place me in jeopardy like that. 
They either need to find an alternative that doesn't affect me like that or I'm inclined to stop the chemo and take my chances with Tamoxifen. 
I don't say this lightly though - it's taken many years to establish equilibrium and maintain a life free from bipolar. Bipolar is more destructive than any amount of cancer - especially for the people you love. 
Anyone else had a similar problem?