[JessicaV]

As the first person replying to this thread said, this study showed that for those early breast cancer patients without the HER2+ factor, and with Estrogen factor, those who only take the hormone-cancelling treatment do about as well as those who take that plus get chemo.
This is not about HER2+ people like all/most of us.
In answer to Chrystald and donocco, I understand that the answer to how and why breast cancers metastasize comes down to stem-cell-like tumor cells. Despite the amount of main-stream professional research going into this issue, few people seem to know about stem-cell-like tumor cells, which are very abundant in HER2+ tumors and much less so in luminal types. I believe this lack of information/interest is because almost all the research into breast cancer is done as trials of drugs, and is funded by drug companies whose interest is in establishing the best dosages to use for different treatment regimes. And because our oncological teams do not see it as relevant, which is ironic because the breast cancer we die of (if we die of it) will almost certainly be metastatic breast cancer. But they are mostly concerned with treating the biggest patient group, ie newly diagnosed individuals with early breast cancer. WHich I cynically think is because it is the biggest market for their drugs.

The research that has been done into stem-cell-like-tumor cells shows that these cells even seed themselves into bloodstream and lymph system, eg as they break out of the cell membrane of the duct they start in to become invasive ductal carcinomas. And they are easily spilt during any biopsy or surgery that breaks open the tumor. Once in the bloodstream, they change form and float around till they find a suitable niche to grow in, in tissue that is of the right sort (eg lung, liver, brain), and if they can establish a food source and not get devoured by the right sort of white blood cell, they develop into a metastatic tumor. This may have happened before we get our diagnosis and have surgery/herceptin/chemo/radiotherapy, or the seeding can happen anytime up to the total removal of the whole tumor. Some stem-cell-tumor cells may find a niche that doesn't support their growth. Some may begin growing before we finish herceptin/chemotherapy, and then get hit by our chemotherapy and wiped out. Some may get consumed by our immune system before they can do anything. Mets are only diagnosed once they are over about 1cm so we don't really know if they are there until they make it big enough and are located somehow. I don't think the individual tumor cells floating in the bloodstream are at risk from herceptin/chemo, only the ones that are still in the breast tissue or have found a niche to metastasise.

The closest our oncological providers get to talking to us about stem-cell-like tumor cells is to recommend we have radiotherapy "to mop up anything left behind" if we have a lumpectomy or are node-positive. And that if we survive NED for 5 years, we then have no more chance that any other person our age without breast cancer of getting it again, back or mets.

It surprised me to discover there was this whole area of high-quality professional research, discovering for example that various food chemicals like tumeric and green tea have substances that can affect stem-cell-like tumor cells. And that there is this complete scientific explanation as to why even if we have every last bit of breast tissue removed, and massive herceptin/chemotherapy and radiotherapy, we may still get metastatic cancer.