I'm having conflict with my mother on the topic of radiation.

 it sounds like the issue isn't radiation- she's done with that- hormone therapy is different. she's probably on an aromatase inhibitor (AI) . mood changes are a common side effect. You are welcome here, the women (and men) on this board are a wealth of information. You sound like a caring son who wants the best for your mom.

I started on Tamoxifen a couple months ago since I'm pre-menopausal (post menopausal women are generally given an AI) . I have certainly noticed some mood changes- tamox and AI's work in different ways but both mess with hormones. I have been on an anitdepressant for years- well before being diagnosed with breast cancer, I had to switch to a different one that worked with tamoxifen.

I have always hated the idea that I had to take a pill to feel decent emotionally- the Tamoxifen /AI mood changes are different for everyone- some women get  better after a couple months- some do better adding a antidepressant along with the AI- it sounds like that is what you think might be called for and your mom doesn't want to do that. that is a common way to feel- I don't want to take a pill to deal with the side efffects from another pill- where does it end?

Many women go off tamox and AI's for these reasons and many more. If it comes down to quality of life- there are natural supplments out there to help our bodies achieve a natural good estrogen/bad estrogen balance- check out threads on iodine and IC3/DIM. who know more about. I  hope some women who know more about AI's will chime in.

I commend you for reaching out for help for you and your mother. it is clear you lover her very much.

I started Tamoxifen back in October, after surgery,chemo and radiation. And I have to say that it was the most frightening part of the entire thing (well, except for the diagnosis).  I felt like the treatments all did things TO me, but the pills could actually CHANGE who I am. I went to see the cancer psychologist at our center a few times because I was so afraid of the mood swings and emotional changes the pills could cause - AND because it is a FIVE YEAR course of treatment. I remember saying in all seriousness to the counselor "I would rather die of cancer than turn into a completely different person." 
Now for me, so far, I haven't noticed anything mood related. Just hot flashes and some other stuff you don't need to read about.  But I did learn that there are things you can do to help with the changes the pills can bring = accupuncture is known to help, also I take DIM to help with the estrogen modulation (not sure if that is the right term). Relaxation/meditation can also be helpful. Anti depressants are helpful as well, but I didnt' want to go that route unless absolutely necessary.

I share all this to let you know how upsetting and frightening it can be to not feel in control of your emotions, ESPECIALLY if she has always been a 'strong tough woman' as you describe.

My suggestion would be to revisit the issue when everyone is calm. Maybe do a little research so you can know how much the medication improves her odds, and then tell her how much you love her and want her to be around for a long long time. I would offer her the info about this message board - she may be interested in joining and getting support. Also offer to go to the onc WITH her to discuss options.  I don[t think the onc's office will speak to you alone due to HIPPA regs, but i may be wrong.  I am hoping your calm and loving plea might sway her to rethink.

Also, if she does stop taking it, she may be willing to revisit it later on once the side effects fade and she feels more like herself. of course this is not optimum, but it isn't all or nothing - even if she does quit, she can always try another one. Don't give up hope. I wish you the best.

The degree of risk she is taking in discontinuing whatever ajuvant therapy she is taking depends on what stage and grade her cancer is.  For example, I had grade 3 DCIS with lumpectomy and rads.  I discovered after taking the tamoxifen for a couple of years that I had liver damage from a previously undiagnosed case of Hepatitis B, and talked to my oncologist.  She told me how much of a percentage it increased my odds by, which in my case was only something like 3%.  So you can pretty much take a calculated risk - the oncologist agreed with me that 3% is not a lot and the effect on my liver was more serious.  Maybe your mom could make an appointment with the oncologist for a consultation - the oncologist isn't going to force anything down her throat.