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Why Tamoxifen if the DCIS has been removed?


Hello Community

I was recently diagnosed with DCIS (2 mm) and had a partial lumpectomy this past Tuesday. The needle biopsy (prior to the lumpectomy) said it was my DCIS was hormone positive, which is a good thing. My estrogen levels are very high. What I don't understand at all is: if the DCIS has been removed, then what is the Tamoxifen going to "block"?


  • quietgirl
    quietgirl Member Posts: 165
    edited March 2022

    In theory it is to decrease the chance of reoccurrence. If your cancer is estrogen positive meaning it uses estrogen to grown/replicate, the goal of drug therapy is to decrease the level of hormones (or for the medication to bind with the hormone receptor so hormones cannot be used by the cell), which reduces the chance of a stray cancer cell or a new similar cancer being able to grow. I'm sure that your doctors will explain it better than I at your follow up visit

  • moderators
    moderators Posts: 7,911
    edited March 2022

    Hi seattle1968, and welcome to! We're sure you'll find this space a helpful, supportive, and informative place. You may find some helpful information in this article: How tamoxifen works.

    Also, we have a popular topic here all about this drug, if you want to take a look: Bottle 'o Tamoxifen.

    If there's something else we can do for you, please let us know. We're here to help!

    The Mods

  • parakeetsrule
    parakeetsrule Member Posts: 605
    edited March 2022

    It helps block the formation of a new cancer from forming, or helps block anything that was too small to see. If you aren't sure if you want or need it, ask your doctor to explain your risk of recurrence and by how much taking Tamoxifen would reduce it.

  • VioletKali
    VioletKali Member Posts: 97
    edited March 2022

    Basically, once you have cancerous cells in your body then you are likely to have something called tumor stem cells, or "circulating stem cells" These cannot be killed by chemo because they are slow growing and not susceptible to it.

    This is why cancers reoccur. I've had a double mastectomy, but technically I have circulating tumor cells that could decide to attach to any compatible organ.

    I personally chose not to do hormonal therapy because it affected my quality of life. I quit it. I know of the risks and I have a yearly full body MRI.