Paxil is a very good medication, and not any harder to stop than the others if it is done cautiously over a three week period. I don't know the study re breast cancer, but ask your doctor to interpet it for you, because if there is an increased risk, and may not be enough to worry about...
My wife had BC, she has already had the chemo and surgery and is now on the part of the treatment focused on preventing recurrence (herceptin and tamoxifen). She had been taking paroxetine for the last two years. Now she started to see the psychiatrist at the cancer centre (the one who routinely sees cancer patients) and the dr advised her to change the paroxetine for another antidepressant. She mentioned the study, but said that it was a bad study (not conclusive) but she prefers breast cancer patients not to take paroxetine just in case. The switch is not abrupt, she first reduced the dose of paroxetine and started with a low dose of the new drug for a while.