The good news from this study is that these problems typically reverse once treatment is finished.
"The overall message here is one of tremendous reassurance," said study researcher Dr. Brian Leyland-Jones, vice president of molecular and experimental medicine at Avera Cancer Institute in Sioux Falls, S.D.
The study was published June 9 in the Journal of Clinical Oncology online. Roche, the maker of Herceptin, provided research funding. Some of the study's co-authors work for Roche or are advisers or consultants.