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What happens after Herceptin treatment?

Medically reviewed by Carmen Pope, BPharm. Last updated on Oct 2, 2023.

Official answer


After Herceptin treatment, your doctor will monitor you regularly for cancer progression, advise you not to become pregnant for at least 7 months (if you are of childbearing potential), and test your heart every 6 months for at least 2 years, because there is a higher risk of developing long-term heart damage in people who take Herceptin.

Seek emergency medical help if you’re taking Herceptin and you develop any symptoms of heart failure. They include:

  • shortness of breath
  • trouble breathing
  • an irregular or rapid heartbeat
  • increased cough
  • swelling of the lower legs or feet.

During treatment with Herceptin, your doctor will test your heart every 3 months.

People who can become pregnant are advised to use contraception during their treatment period and for 7 months after treatment with Herceptin ends because Herceptin may cause low levels of amniotic fluid in the baby that can lead to underdeveloped lungs and neonatal death.

A long-term study that followed women with early-stage HER2-positive breast cancer for 8-plus years, reported that adding Herceptin to chemotherapy significantly improved the overall and disease-free survival. There was a 37 percent improvement in survival and a 40 percent reduction in risk of cancer occurrence, compared to patients treated with chemotherapy alone. There was also no increase in the incidence of secondary cancers and only a minor increase in heart problems.

In terms of overall survival, in people given Herceptin plus chemotherapy for breast cancer treatment:

  • 6.78% more patients are still disease-free than those just assigned chemotherapy
  • The overall estimated median survival is 7.5% higher in the Herceptin with chemotherapy group.

When Herceptin plus chemotherapy was given for Metastatic breast cancer, there was:

  • 2.7 months longer median time to disease progression compared to the chemotherapy group
  • 2.5 months longer median duration of response compared to the chemotherapy group
  • 4.8 months longer median survival compared to the chemotherapy group.

When Herceptin plus chemotherapy is given for Metastatic Gastric Cancer treatment, there were:

  • 6.2% fewer deaths compared to chemotherapy.

Treatment with Herceptin usually lasts 6 months to 1 year when it is used for early HER2+ breast cancer, or it is given until disease progression or intolerable side effects occur when it is given for HER2+ metastatic breast cancer or metastatic gastric cancer.

Related questions

  • Herceptin (trastuzumab) Updated 02/2021. Genentech, Inc.
  • Years after treatment for HER2-positive early-stage breast cancer, trastuzumab continues to show life-altering benefits. Science News. Oct 20, 2014.
  • E. A. Perez, E. H. Romond, V. J. Suman, J.-H. Jeong, G. Sledge, C. E. Geyer, S. Martino, P. Rastogi, J. Gralow, S. M. Swain, E. P. Winer, G. Colon-Otero, N. E. Davidson, E. Mamounas, J. A. Zujewski, N. Wolmark. Trastuzumab Plus Adjuvant Chemotherapy for Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer: Planned Joint Analysis of Overall Survival From NSABP B-31 and NCCTG N9831. Journal of Clinical Oncology, 2014; DOI: 10.1200/JCO.2014.55.5730

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