i was thought to have carried the brac1 gene from my fathers side...but fortunately didn't. My half sister (same mother) had breast cancer and so has her daughter. My sister unfortunately died from her bc but my niece is still cancer free 14 years on after the same aggresive treatment I had. She was in her early 30s when diagnosed with 2 young children.
Because of my family history I'd been having mammograms since age 40 every year. At age 51 I found a lump....5 weeks after a clear mammogram. So....even knowing where the cancer was it was invisible. I had an aggresive es+ her2+ grade 3 cancer...stage 1. I was very fortunate to have found it before it had spread...and this was purely due to location. I try not to imagine what would have happened otherwise.
I chose a bilateral mastectomy and reconstruction at my surgeons recommendation . We have as yet no identified gene. My niece chose the same. And although treatment might seem drastic...the alternative can be risky if undetected. Chemotherapy is no walk in the park, nor is herceptin if cancer develops...I had heart failure from herceptin. Under the new pbs guidance I would have been offered tamoxifen before cancer developed and I would have seriously considered it. You can always stop if effects outweigh the benefit.
Ask also about your breast density, if ultrasound should be added and possibly the new 3d mammogram. Ask about your genuine risk of having breast cancer in your lifetime , knowing the stats can really help.
I know it is a difficult decision but you need to outweigh risks with benefits. You have time to find out more. The decision doesn't have to be made in an instant. Tamoxifen can also give you time to consider long term options.