Trastuzumab (Herceptin): — What to Expect from Your Treatment

Trastuzumab alone does not typically cause significant hair loss. Hair loss that you notice during treatment is almost always caused by chemotherapy given alongside it, not by trastuzumab itself. If you are receiving trastuzumab as a maintenance therapy on its own after chemotherapy has ended, hair loss is not an expected side effect. Ask your oncologist which drugs in your regimen are responsible for which side effects so you have an accurate picture of what to expect at each stage.

Trastuzumab can reduce how efficiently the heart pumps in some patients. You may not feel this in the early stages, which is exactly why the regular LVEF scan is built into your treatment schedule rather than only done when you feel unwell. Report any new shortness of breath at rest or on minimal exertion, swelling in your ankles or legs, unusual fatigue that comes on quickly, or a sensation of your heart beating irregularly. Contact your team promptly — do not wait for the next scheduled appointment.

Yes. Biosimilars approved by CDSCO in India must demonstrate clinical equivalence to the originator product before they are permitted for use. They carry the same active molecule and work through the same mechanism. The difference lies in the manufacturer and, often, the cost to the patient. Your oncologist or hospital pharmacy will specify which product you are receiving. If you want reassurance, it is entirely reasonable to ask your team for the product name and its approval status in writing.

Duration depends on your cancer type and stage. ASCO and ESMO guidance for early HER2-positive breast cancer typically recommends a period of approximately one year of trastuzumab-based treatment. In advanced or metastatic disease, trastuzumab is generally continued for as long as it is working and tolerated. Your oncologist will discuss the intended duration at the start of treatment and reassess at each response-evaluation point. Changes to the plan will always be explained to you.

A pre-existing heart condition is not an automatic reason to exclude trastuzumab, but it requires careful assessment before treatment begins. Your oncologist and, often, a cardiologist will review your current heart function and history to weigh the potential benefit against the additional cardiac risk in your specific case. If treatment goes ahead, monitoring is usually more frequent than for patients without a cardiac history. Be specific and complete when describing your heart history and any cardiac medications you are currently taking.

Contact your oncology team as soon as you know you will miss an appointment. For trastuzumab, the interval between infusions matters — a long gap may mean a reload dose is needed before resuming the regular schedule, rather than simply continuing where you left off. Do not arrive at the next scheduled appointment as though the gap did not happen, as the dosing plan may need to be adjusted. Your team will tell you exactly what the revised schedule looks like once they know how long the gap has been.