Hi there @Tillycat, yes treatment is definitely worth it. You may or may not get side effects but better to give it all a go. There are ways to manage side effects and if you get any please talk to your oncologist or breast care nurse.
I had a lumpectomy. My pathology wasn't great so heavy duty treatment for me. I had chemo. I lost my hair. I never got sick. My oncologist said if I got sick she would have failed at her job. I did get fatigue but I did walk every day and do some gentle weights and other exercise. I got a little chemo brain off and on but I am fine. I did get a bit of neuropathy in my toes and the chemo was adjusted. There is always somewhat can be done to reduce side effects.
I also had radium and this was ok. I had a couple of sore areas but they healed very quickly.
I was on tamoxifen and did ok for over a year on that and then hot some side effects. After discussing these with my oncologist we stopped the tamoxifen and I started on Letrozole. So far it's ok but I do have some stiffness.
I love life , my family and friends. I love my home and cat, my holidays and just enjoying every day. I am 2.5 yrs post diagnosis and I think every thing I have been through is worth every day I get to be here.
I guess my message is stay in moment. Don't get too far ahead of yourself worrying about what might happen. It may not but if there are issues, speak up and they can be addressed. Treatment is definitely worth it. Take up a new hobby, try meditation or yoga or something to help yourself. Even just sitting and deep breathing helps. Good luck with your treatment.