How long does HER2-targeted therapy take to work for HER2-positive breast cancer?

HER2-positive means that testing found increased HER2 activity or protein in the cancer cells, making HER2 a treatment target. The medicine may reduce growth signals before you notice a visible or physical change. Your plan can involve treatment before surgery, treatment after surgery, or treatment for cancer that has spread, so the review schedule is individual. The team may check the breast or other affected areas, review symptoms, and use imaging or laboratory tests. One early visit usually cannot describe the whole response.

Keep every treatment and monitoring appointment, even if you feel well. Note changes in pain, swelling, breathlessness, palpitations, appetite, and daily activity so you can describe them accurately. Tell the team about heart problems, lung symptoms, pregnancy, and all medicines or supplements. Ask which test will measure response and when it is expected. Continue treatment exactly as prescribed unless the oncology team tells you otherwise; a lack of an immediate sensation does not mean the medicine is ineffective.

Call your oncology service promptly for a fever, new or worsening cough, breathlessness, chest discomfort, rapid or irregular heartbeat, fainting, or unusual swelling. Report a rash, flushing, dizziness, or throat tightness during or soon after an infusion. Severe breathing trouble, collapse, or facial and throat swelling needs emergency care. These warning symptoms concern possible treatment reactions or effects on the heart and lungs; they are separate from the planned tests used to measure cancer response.

What result from my HER2 test guides this treatment? When is my first response review? Will surgery, chemotherapy, or another medicine be part of the plan? Which heart or lung checks do I need? Who should I contact outside clinic hours?