Cardio-onc boards: trastuzumab

58F on trastuzumab for HER2 positive breast cancer. No cardiac symptoms.

baseline LVEF 61%, GLS -20%
now LVEF 53%, GLS -16.5%

What do you do?

A. Stop trastuzumab
B. Continue, start cardioprotection, increase surveillance
C. Continue with no change
D. Stop and rechallenge in three months

Thats a 17.5% relative fall in GLS with the EF still at or above 50 and no symptoms, which is mild asymptomatic cardiotoxicity. The GLS is what makes it real, the EF alone would have told you nothing.
Mild asymptomatic disease is not by itself a reason to interrupt HER2 therapy, so A stops cancer treatment for a number that hasnt hurt her. C ignores a signal that should change management. Relative GLS decline greater than 15% from baseline is the threshold worth memorising.

so, settled on one? its B.

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