Breathlessness after breast cancer radiotherapy, could it be a late effect?

[BatshitCrazyWoman]

I had breast cancer and finished my active treatment with radiotherapy - final session was mid-April 2025. I've noticed that I get quite breathless when walking up hills (I live on a hill!) or on exertion.

I've been working on regaining fitness since treatment ended , as I lost so much weight and muscle during chemo. I do weights and some cardio, but the breathlessness is bothersome

I read in passing something about lung issues after radiotherapy, sometimes starting a year or more afterwards. Has anyone else had this? Should I go to the doctor?

Of course you should speak to your doctor about this.

You should definitely speak to your oncologist or at least your GP about this. They should give tests due to your health history. It doesn't mean something is wrong but get used to being in the 'priority for ruling things out' category due to recent cancer.
Ask for lung x-rays and breathing tests.

Definitely see your doctor. There are lots of things that can cause breathlessness on exertion after cancer treatment, some related and some not. Your doctor can investigate and advise on what can be done.