All DCIS her2+?

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Rrobin0200
Rrobin0200 Member Posts: 433

I’ve heard that all DCIS is Her2+. Is that true?

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  • Beesie
    Beesie Member Posts: 12,240
    edited May 2019

    No.

    About 40% - 60% of DCIS cases are HER2+, vs. about 15% - 20% of IDC cases.

    Most often DCIS isn't tested for HER2. This is because HER2 status doesn't appear to affect DCIS. There have been lots of studies, and while a few do suggest that HER2+ DCIS may be more aggressive, a few actually show the opposite, that HER2+ DCIS may be less aggressive. And most of the studies show no difference in prognosis whether the DCIS is HER2+ or HER2-. Because there is no difference in prognosis, there is also no difference in treatment for DCIS whether it's HER2+ or HER2-. Therefore HER2 testing is unnecessary; it provides information that adds nothing to the diagnosis, prognosis or treatment plan. It is unactionable information.

    This is very different from invasive cancer, where it is well established that HER2+ invasive cancers are very aggressive and without adequate treatment, have a less favorable prognosis. Herceptin, combined with chemo, has been a game-changer for HER2+ invasive cancers, bringing survival rates right in line with much less aggressive breast cancers.

    While over the years there have been a couple of very small, limited-use trials of Herceptin on DCIS patients, Herceptin is not approved for DCIS.


  • Rrobin0200
    Rrobin0200 Member Posts: 433
    edited May 2019

    thank you for your response!! This is all just so much!

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