IDC is the most common type of breast cancer (>70% of invasive breast cancers)

Treatment:

Stage I  Surgery (Breast conserving surgery [BCS] or mastectomy *with sentinel lymph node biopsy [SLNB] or axillary lymph node dissection [ALND]), *then RT (generally not required if mastectomy performed), then *adjuvant chemotherapy (unless tumor < 1cm with no unfavorable features), hormone therapy (for ER+ or PR+ tumors) x 5 years, trastuzumab (for HER2-positive tumors) x 1 year. Reconstructive surgery may be considered after RT.

Stage II  *Neoadjuvant systemic therapies can be considered to shrink tumor so that BCS becomes an option, but this *does not improve mortality; pertuzumab is typically added to trastuzumab in neoadjuvant HER2-directed therapy, followed by Surgery (Breast conserving surgery [BCS] or mastectomy *with sentinel lymph node biopsy [SLNB] or axillary lymph node dissection [ALND]), *then RT (generally not required if mastectomy performed), then *adjuvant chemotherapy (unless tumor < 1cm with no unfavorable features), hormone therapy (for ER+ or PR+ tumors) x 5 years, trastuzumab (for HER2-positive tumors) x 1 year. Reconstructive surgery may be considered after RT.

Stage III –     Option 1) *Neoadjuvant systemic therapy followed by surgery, RT +/- adjuvant systemic therapy: Neoadjuvant chemotherapy (+/- neoadjuvant HER2-directed therapies) before surgery. Tumor size may shrink enough for BCS, but mastectomy may still need to be performed. *SLNB not an option, ALND performed. RT usually required after surgery. Reconstructive surgery may be considered after RT. Adjuvant hormone therapy (for ER+ or PR+ tumors) x 5 years, adjuvant trastuzumab (for HER2-positive tumors) x 1 year +/- adjuvant chemotherapy. –     Option 2) *Surgery followed by RT and adjuvant systemic therapy: *Mastectomy usually required (BCS for tumors that have not grown into nearby tissues + large breast size). Most will need ALND. Surgery is usually followed by adjuvant systemic chemotherapy, and/or hormone therapy, and/or trastuzumab. Radiation is recommended after surgery. Reconstructive surgery may be considered after RT.

Stage IV  *Palliative systemic therapy; depending on receptor-status of tumor and patient symptoms. For ER-/PR- tumors, chemotherapy is used. For ER or PR positive tumors, hormone therapy is given first (unless mets causing symptoms [ex: SOB from lung mets], in which case chemotherapy is started first, since hormone therapy takes months to work); *postmenopausal pts receive palbociclib + letrozole; premenopausal pts receive tamoxifen. For HER2+ tumors, trastuzumab with first chemo improves mortality. Trastuzumab can also be given with letrozole or pertuzumab + chemotherapy. Another option is ado-trastuzumab emtansine, which is given until the tumor starts to grow again. *RT, surgery, regional chemotherapy can be palliative in certain situations (open wound, small number of grouped mets, mets pressing on spinal cord, to prevent bone fxs). Bisphosphonates (or denosumab) + calcium + vit D for pts with bone mets.

*High-yield

MALIGNANT BREAST DISORDERS:

Invasive Ductal Cancer (IDC)