Positive node in unaffected breast

After my cancer returned, seven years after a lumpectomy, I decided to have a double mastectomy. Some nodes were taken from the unaffected side and one was positive for cancer. How did the cancer travel to this node? There was no cancer found in the breast tissue of that breast.

My original cancer was ER Positive - it is now triple negative. Is this a new primary, or did my original cancer change into TNBC?

Thank you.

[bluebutterfly2222]

I not sure about the node, but the change from ER+ first cancer to a ER- recurrence after the use of tamoxifen has been found in various research studies.

(This may not apply to your situation, but it does give some indication regarding how it can happen.)

In one study, women who used tamoxifen or other breast cancer hormone therapies were 60% less likely to develop an ER positive cancer in their other breast, compared to those who never took tamoxifen. But women who used tamoxifen for five or more years were about four times more likely than women who never used breast cancer hormone therapies to develop an ER negative tumor in their other breast.

The study wasn't designed to show a woman's absolute risk of developing an ER negative breast cancer."This is a relatively rare type of second cancer. In our study, only 25% were of this type," So for the vast majority of cancers, [tamoxifen] is lowering the risk of second cancers. But for the smaller subset, this 25%, it's increasing the risk. The researchers aren't sure how tamoxifen might raise ER-negative breast cancer risk, but they speculate that targeting ER-positive cells may allow ER-negative cells to take center stage.

The researchers didn't call for any change in how tamoxifen is used in breast cancer patients, or for taking tamoxifen for less than five years, because overall, the benefits still win out. "Any sort of treatment has risks and benefits, and the benefits for tamoxifen are very clear, particularly with respect to reducing mortality. It also reduces the risk of recurrences."

Sorry I don't have more than this to offer...
bluebutterfly