Hello again, everyone, and thanks SO much for your answers. I just talked to my sister. She is so funny; she knew I would want every detail, so she is going to fax me the copy of her doctor's report! But the brief outcome is this: lymph nodes clear, lump was Grade 1, all removed; she will have 5 weeks of radiation followed by tamoxifen for 5 years, as it's hormone receptive. She will have to come off the pill (her boyfriend is "ready to cut his willy off" in disappointment) and will have annual mammograms.
She has three friends arguing over who gets to drive her to treatment, so altogether the news is as good as it can be.
Thanks again, everyone!
Much more relieved in Massachusetts