low WBC on Tamoxifen?

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revkat
revkat Member Posts: 763
edited September 2014 in Hormonal Therapy - Before, During, and After

I've been stewing for 3 day about this, so I thought I'd ask the experts!

I am 6 months past chemo (TC -- no prob with counts then, but on neupogen); and 3 1/2 months past radiation. I've been on Tamoxifen for 3 months now. My WBC count was really low at the first post-rads-time-to-begin-tamox appt (1.9). It's been checked 3 times since then and has never gotten higher than 2.4. At the last appt. the onco sent me for another CBC, and said she would look at the cells under the microscope. That was Wed. at 5, so of course I haven't heard anything back.

This is the part I don't understand. The onco also said the absolute numbers of each kind of white blood cell were ok so I don't need to worry about fighting infections. I don't understand how the total is so low then? I wish I'd asked, but she was muttering thing about blood marrow biopsies and I was busy freaking out about that. And then I googled tamox and WBC to discover that low WBC is a rare side effect, but the only thing I could find that we should do about it is monitor closely.

Anybody else run into this? Any microbiologists have any insight (cough, Otter, cough)?

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  • roseg
    roseg Member Posts: 3,133
    edited December 2008

    I don't think tamoxifen has as much to do with your counts as your prior chemo has.

    You could stop taking it for a couple of months and see if they improve. But chemothearpy tends to be hard on your bone marrow. 

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  • revkat
    revkat Member Posts: 763
    edited December 2008

    Would chemo cause counts to go down after the chemo is done and the counts are back to normal? When I finished chemo and before rads the counts were fine. Now that I think about it, maybe it is related to the radiation treatment. It was after rads that the first dropped so far. I know rads can cause wbc to drop. I wonder how long it is supposed to take for them to come back up?

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  • otter
    otter Member Posts: 6,099
    edited December 2008

    revkat, I don't see any experts wandering around here...  :)

    I did google "tamoxifen x leukopenia" and I got lots of hits.  Leukopenia (or "leucopenia", for our friends in the U.K.) is reported as an infrequent SE of tamoxifen therapy.  As you probably know, "leukopenia" means that the total number of WBC's is below the reference range.  "Neutropenia" means the neutrophil concentration (relative % or absolute #) is below the reference range.  Apparently, neutropenia can occur on Tamoxifen but it is "rare".   This website-- http://www.druginfonet.com/tamoxfen.htm --talks about WBC in women on Tamoxifen:

    "Leukopenia has been observed, sometimes in association with anemia and/or thrombocytopenia. There have been rare reports of neutropenia and pancytopenia in patients receiving Tamoxifen Citrate Tablets; this can sometimes be severe."

    I don't know how long after chemo our counts can be down, or in your case, go down.  It seems odd that it would occur this long after finishing TC.  (Mine haven't been checked since right before TC #4, so I don't know what they are now.) 

    And, I'm sorry that I don't know whether rads can cause counts to go down.  Seems like if the rads are focused on the breast, they wouldn't affect bone marrow; but I guess the ribs and sternum and maybe the collarbone could be in the field.  How much functional bone marrow is in those bones, though?  Not much, if we're not young anymore.  I guess it's possible to have an indirect effect of rads (due to the soft tissue damage) mess up WBC production by the bone marrow.  Never heard of that, though.  OTOH, some websites say rads for BC can cause neutropenia--this site, for instance: 
    http://breastcancer.about.com/od/treatments/g/neutropenia.htm 

    You said this: "The onco also said the absolute numbers of each kind of white blood cell were ok so I don't need to worry about fighting infections. I don't understand how the total is so low then?"  I agree--that confuses me, too.  It would make sense if the relative numbers (the percentages) were okay, but the total was down--that can happen.  But in your case, the absolute numbers are okay, but the total is down...  The only way that makes sense is if the absolute number of each type of cell is down at the bottom of the reference range for that cell type, and those numbers added together produce a total that is below the reference range for total WBC.

    That's pure speculation on my part, though.  Your onco will need to sort this out.  If I were you, I would try not to worry about it, because it's likely that there is nothing wrong at all.  My onco told me some people are just at the low end of the range, normally.  (Somebody has to be there, I guess.)

    Hugs, revkat.  Wouldn't it be nice if we could stop worrying about all this stuff?

    otter

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  • revkat
    revkat Member Posts: 763
    edited December 2008

    Thanks Otter.

    I heard from the onco today and this last cbc was up to 3.8 so we are just going to watch it for a while. In my web wanderings I found a story of a woman who low wbc ended up being a rare side effect of femara. Sometimes it seems like we just can't win.

    Oh, and what was good was the differential not absolute counts, so I think what you said about the percentages being ok was what she meant. I am actually a fairly intelligent person, but when she said "bone marrow biopsy" my mind totally left me! Anyway, we won't be going there, for which I am very grateful.

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  • swinn
    swinn Member Posts: 125
    edited December 2008

    revkat,

    I have always carried a low white blood cell count before I had bc. It was as low as 3.7 already and they did a lot of other testing and came up with nothing. My doctor said most likely I just carry a low WBC count and that is normal for me. I don't catch everything that goes around either. 

    Sally 

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  • robsp
    robsp Member Posts: 50
    edited September 2014

    I started tamoxifen one week after radiation and now, 3 months after chemo,   5 weeks after
    radiation and 4 weeks from the first pill of tamoxifen, my WBC is around
    2 (Normal is above 3.7), my neutrophil count is 0.9 , normal is above
    1.7.

    Unfortunately my doctors did not required blood count
    during and right after radiation and now I do not know if my low blood
    count is due tamoxifen, radiation or a late side effect of chemo.

    Anyone had low blood count after radiation or due tamoxifen ?

    I will visit the RO and MO this week. 

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