I guess breast cancer isn't the clinical term. She had cancer in her mammaries in 2002. One entire chain was removed, and only one on the other side (removing all of them would have been too traumatic, the surgeon said). Now it's recurred in one of the remaining ones.
The vets are amazed that she's survived this long, especially with no chemo ever. Average survival post-op is 2 years with chemo. She 14 years old now, and we're not sure she could withstand another invasive surgery like that after all she's been through. We might just go with chemo this time and hope for the best.