Dear Debsis, This report of a biopsy indicates that there is invasive cancer that would need further treatment. Because of positive margins (Multifocal involvement. . .is identified)more surgery would be indicated. The other information such as ER/PR receptors lets the doctors know that this type of cancer is receptive to estrogen and progesterone, and that will be important in terms of recommendations for hormone treatment. Some of the other information that will help in terms of further treatment recommendations will be determined with surgery. These include what the size of the tumor is (1.1cm is not a for sure because of the positive margins). And the lymph node status which is checked with further surgery.
Your sister's surgeon will use the information from this biopsy report as well as any other test results in order to discuss treatment options. What your sister would want to hear from her/him is the risks and benefits of the different surgical options in order to make an informed decision about the next step in treatment.
The not identified comment means in this sample of tissue they do not see blood/lymphvessel invasion or any insitu component to the cancer. The blood/lymphvessel invasion comment doesn't mean there is no lymph node involvement - whether or not lymph nodes contain cancer is determined once the lymph nodes are sampled through surgery. In situ means that the cancer is confined within the duct of the breast, however the invasive component is what takes precedence in regard to treatment whether or not there is insitu cancer found.
I recommend that you or your sister may want to get Dr. John Link's book "The Breast Cancer Survival Manual". It's for newly diagnosed patients and it explains very simply how to read your pathology report as well as explains a lot of the surgical and treatment options. You're doing the right thing in trying to become knowledgeable before her appt.