When given in combination with dose-dense chemotherapy for women with human epidermal growth factor receptor 2 (HER2)-positive breast cancer, adjuvant trastuzumab should be administered for 12 months rather than 6 months, a new study published in the journal Annals of Oncology has shown.

For the study, researchers sought to compare 12 versus 6 months of adjuvant trastuzumab in women with HER2-positive early breast cancer.

Researchers enrolled 481 patients with axillary node-positive or high-risk node-negative, HER2-positive early breast cancer and randomly assigned them to receive 12 or 6 months of adjuvant trastuzumab concurrently with dose-dense, G-CSF-supported docetaxel. All patients also received upfront dose-dense, G-CSF-supported FEC.

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Results showed that the 3-year disease-free survival was 95.7% in the 12-month treatment group compared with 93.3% in the 6-month treatment group (HR = 1.57; 95% CI: 0.86-2.10; P = 0.137).

Researchers observed no difference in overall survival. The study showed that after 47 and 51 months of median follow-up, 7.1% and 11.7% of patients in the experienced disease relapses in the 12- and 6-month groups, respectively (P = 0.08).

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In regard to safety, there was no difference in cardiotoxicity between the two groups.

Because the study failed to show non-inferiority for the 6-month administration of adjuvant trastuzumab, the authors conclude that the current standard of care that is adjuvant trastuzumab for 12 months should be continued.


  1. Mavroudis D, Saloustros E, Malamos N, et al. Six versus twelve months of adjuvant trastuzumab in combination with dose-dense chemotherapy for women with HER2-positive breast cancer: a multicenter randomized study by the Hellenic Oncology Research Group (HORG). 2015. [Epub ahead of print]. doi: 10.1093/annonc/mdv213.