First of all, please do get second and third opinions since yours is a complicated system. And specialists aren't always broadly-educated. Or can become too narrowly focused. I'm reminded of an old cautionary adage, "to a hammer, everything is a nail." I think it's particularly true of specialists and our medical care can get too compartmentalized. And I second Chris' suggestion that you try to find a medical institution that can help. I switched from a lone primary care practice to an excellent PCP within a renowned clinic and that has been an enormous improvement in my comprehensive care.

As to your question, I'm new to the breast cancer experience so, since I was diagnosed in October, 2021, I've been reading as many relevant studies as I could. I cannot remember the name of it, but one study questioned whether many breast cancer recurrences are in fact not actual recurrences as thought of in lay terms, but more likely separate isolated incidents. The researcher looked at the meta data and questioned the prevailing thinking about how breast cancer cells likely metastasize. He posits that, in a sense, one can be unlucky with breast cancer and get it more than once without the two events being biochemically related. That might make sense since one's genes remain the same during and after breast cancer as do one's essential biochemistry and environment. So whatever factors allowed the first cancer cells to thrive remain, though geld in abeyance with the various therapies while one is participating in them. But the reality is that medical science has yet to decode the many mysteries of cancers or the human body. The good news is how many things can be treated today while we all learn more. Your medical saga being a case in point and merits applauding you for getting through it with grace.