My mum's breast cancer was found by annual mammogram, also very early stages, no lymph node involvement. Nothing abnormal was seen on her mammogram the previous year. She only had a mastectomy; chemo, radiotherapy were not deemed necessary for such a small, early cancer. She died 5 years later. Cancer is a sneaky bugger, especially BRCA cancers it seems.
Speaking for myself, the stress of annual MRI scans, which I was entitled to on the NHS, was too much to bear. I felt like I was waiting for a diagnosis and am so much happier now that I have taken control of the situation.
I think anyone who has experienced cancer will tell you that life is never the same after a diagnosis. It's not a case of get diagnosed, get cured, resume life as you were. After her diagnosis, mum always felt that there was a bogeyman lurking in the shadows - unfortunately for all of us she was right. I didn't want to live in fear, before, during or after diagnosis, when I could take charge and hopefully avoid the whole thing.
So it may seem extreme, but for me it was the only way to gain peace of mind and I am a million times happier now that I've had the surgery.