Its a huge dilemma. From experience my mother went for her first mammo at age 60 in those days and they found very aggressive breast cancer that had already spread to lymph nodes but it was a type that did not form a lump just scattered cells around breast. With op and drugs she lived another 8 years, if she hadn't had the mammo when she did they said it was so aggressive she would have been dead in 6 months
BUT her type of cancer was rare and I know loads of people who have had invasive treatment for DCIS which is pre cancerous and probably would have never been a problem in their life but once known they treat.
Plus a breast surgeon said to me that the cumulative doses of radiation can itself cause breast cancer and compressing a cancerous breast can cause the cancer to spread
Because of my mother I do go for screening, ultrasound with mammo is the best combination but not available on nhs.
I have a friend who refuses to go for screening, she is the happiest person I know!
So goodness knows whats the best thing to do