I have had a benign breast tumour in the past. I've still decided to take HRT, only just started, on patches. I think someone recommended listening to a Dr Renee on you tube about this. I think it's important everyone does their homework and it's a very personal decision, I am of the opinion (and it's an opinion and I'm not a scientist) that if something works for you then it's doing a lot of good. And breast cancer can occur for so many different reasons and might even occur for some people because of their hormones being so out of whack. There's evidence that not sleeping can cause breast cancer in some people (not huge evidence, and it is linked to other cancers and diabetes and heart disease too) and there's evidence that sleeping pills can do harm, maybe even be carcinogenic. I'm just trying to say that there's so many ways of looking at it, and possibly, some bio identical hormones that your body is used to might be better for you than not sleeping or sleeping pills. Once I started taking HRT I noticed so many improvements that I didn't even know needed improving, my concentration was better, my mental energy was better and I didn't even realise they were suffering.
But it's just another perspective, as you already know this has to be a personal decision.