Tamoxifen and Ovarian Cysts

I was diagnosed with breast cancer in January when I was 50. Baseline tests revealed I had a small (2cm) ovarian cyst on each ovary- considered not a problem. This was not too surprising to me. When I was 20 I had 2 chocolate cysts the size of “small oranges” removed from my ovaries. I was put on 2 nine month durations of Provera to induce ‘pseudo-pregnancies’. When I was 25 (1975), I had more surgery. For 4 hours the doctor removed microscopic bits of endometrial tissue, removed adhesions, and put my organs back into place. He followed that up with daily “tubal flushes” for a week to keep my fallopian tubes open. After 2 miscarriages it was determined that I had an ‘inadequate luteal phase’. In 1977 I got pregnant and was one of the first users of progesterone suppositories. It worked and I have a wonderful son. For years things were okay. Ten years ago I started having very heavy periods, very frequently (10 days long every 21 days). I had large fibroids. My gynecologist suggested a hysterectomy. I knew I’d be better off keeping myself intact and looked for alternatives. I asked him about an endometrial ablation and he referred me to another specialist. That worked great for me. I still had minor spotting at the time of my periods… but that was no big deal. However, I also continued to have cramps. Now I have the breast cancer diagnosis and I had a lumpectomy and radiation. I started the tamoxifen in March. I was perimenapausal at this point, but the Tamoxifen stopped what little spotting I had. In June, I started getting some strong cramping. I had a transvaginal ultrasound and it showed that my left cyst and increased from 2cm to 4.5 cm, but described as “simple”. My oncologist ordered a blood test and it showed my estradiol levels as high (386). I should mention that I had genetic testing and I came up negative for the BRCA1 and 2 genes. Also I had a CA125 in Mar and it was low. So this appears not to be cancer, but just a simple cyst that is causing me discomfort. The doctors would like to reduce my estrogen level because of the breast cancer. There has been talk of surgical or chemical removal of the ovaries. Luckily my oncologist suggests we wait and see if the cysts continue to grow before we decide anything. Do you have any experience with patients on Tamoxifen? If I have the cyst alone removed, will they most likely return in the Tamoxifen environment? My endometrial ablation has caused my uterus to become inaccessible to a endometrial biopsy because of scarring. I am worried about how I would detect endometrial cancer in the next 5 years on Tamoxifen. Thanks for any insight you might have.

Dear ritavv-
In general, Tamoxifen should not effect the production of simple ovarian cysts, nor endometrial cancer.
If your body as the propensity to develop cysts, it will do so, regardless of taking the Tamoxifen.