How effective is HER2-targeted therapy for breast cancer?

HER2 is a protein that can encourage some breast cancer cells to grow. Testing a biopsy helps show whether the tumour has increased HER2 activity. When it does, a targeted medicine can block HER2 signals or help the immune system recognise affected cells. Treatment may be used before surgery, after surgery, or for cancer that has spread. Doctors assess benefit through examination, imaging, pathology and how long the disease remains controlled.

A response can mean that a tumour shrinks, becomes easier to remove, or shows no further growth for a period. A treatment may still be useful when it does not remove every cancer cell, and another medicine may be added or substituted if the response is limited.

Ask whether your biopsy included HER2 testing and whether the result is clear. Your oncology team can explain the intended goal, the medicines being combined, the treatment schedule and the checks used to follow response. Tell them about heart problems, breathing symptoms, pregnancy plans and all medicines or supplements, because these details can affect treatment selection and monitoring.

Keep a record of new symptoms between visits. Do not stop an infusion or tablet without discussing it; dose changes, pauses or a different targeted option may address side effects while preserving the treatment plan.

Contact your oncology service promptly for fever, chills, a new cough, breathlessness, chest discomfort, fainting, swelling, severe diarrhoea, repeated vomiting or an allergic-type reaction during or soon after treatment. Seek emergency help for severe breathing difficulty, facial swelling, confusion or collapse. These symptoms need assessment because targeted medicines and their combinations can affect the heart, lungs or immune system.

Which HER2 result applies to my tumour? What is the goal of treatment at my stage? How will you measure response? Which side effects should I report the same day? Will I need heart monitoring or other tests? What alternatives are available if this plan does not control the cancer?