frozen pea friday: researching tamoxifen

a tamoxifen pilltoday is frozen pea friday, and as usual, i’m writing about cancer.

a friend of mine who just underwent a mastectomy and will most likely get the recommendation to take tamoxifen in the near future was asking some of her friends to do a bit of research for her (remember, sifting through tons of information can be a heavy burden for someone with cancer). so i decided to do that here. when i looked for information i tried to take into account that we are looking for information for someone who is not postmenopausal, which makes it a bit tricky because most material seems to concentrate on older women.

first of all, let’s remember this: research has shown that not all breast cancer web sites contain correct information. i think i have a relatively good nose for reliable information but let’s take all of this with a big grain of salt, shall we?

what is tamoxifen?
tamoxifen, or nolvadex®, is a drug that interferes with the activity of estrogen, a female hormone. (see this article at women to women for a discussion of the connection between estrogen and breast cancer). tamoxifen has been used for more than 30 years to treat breast cancer. the known, serious side effects of tamoxifen are blood clots, strokes, uterine cancer, and cataracts. other side effects include menopause-like symptoms. the results of the breast cancer prevention trial (BCPT) showed a reduction in diagnoses of invasive breast cancer among women who took tamoxifen for 5 years.

a good overview of tamoxifen is on a site i had never seen before, organized wisdom. it is a human-powered health search service. their guides and physician reviewers create WisdomCards to help people find the best health information, products and services on the web. i’m not sure what their background is (are they big pharma driven?) but i found their summary on tamoxifen helpful, particularly the indications and contra-indications of tamoxifen.

tamoxifen, goserelin, chemotherapy and ovarian ablation
ovarian ablation [i.e. removing the ovaries, because of their hormone production] with goserelin is equivalent to CMF [cyclophosphamide, methotrexate fluorouracil – a chemotherapy treatment] without tamoxifen, and goserelin plus tamoxifen is more effective than CMF without tamoxifen. if one has a premenopausal patient with ER-positive, lymph node-positive breast cancer, goserelin plus tamoxifen is a good alternative to treating her with intravenous CMF without tamoxifen while achieving the same results.

what happens after the first five years of tamoxifen?

the received wisdom seems to be that tamoxifen is fine for preventing the recurrence of breast cancer for the first five years. what happens after that seems to be a a thing of debate.

1. take letrozole
currently, women whose tumors were fueled by the hormone estrogen can take the drug tamoxifen after undergoing surgery, radiation and chemotherapy to reduce their risk of a recurrence. but tamoxifen only helps for five years. after that, it may be dangerous.

a recent study in conducted in canada reveals that breast cancer patients treated with the drug femara® (letrozole) several years after completing treatment with tamoxifen (nolvadex®) have a reduced risk of a recurrence. these findings were published in the journal of clinical oncology.

supposedly, letrozole is very similar to anmidex, a drug that my twitter friend susan reynolds – the original princess of the frozen pea – is planning on taking after her 5-year run with tamoxifen.

how similar different drugs really are is up for question, as this article in the obstetrical and gynecological survey shows. i certainly remember from my work with people with chronic pain that the minutest changes in medication can have a significant effect.

2. stick with tamoxifen
7,154 women at high risk for breast cancer were randomized to 5 years of daily tamoxifen or placebo. (such a placebo-controlled trial couldn’t be undertaken today for ethical reasons because tamoxifen is now approved as a breast cancer chemopreventive agent).

the primary end point was the incidence of breast cancer, which at 10 years was 3.9% in the tamoxifen arm and 5.5% with placebo, for a highly significant 29% relative risk reduction. this result included a 38% reduction in ductal carcinoma in situ and a 27% decrease in invasive breast cancers.

there were 87 estrogen receptor-positive invasive breast cancers in the tamoxifen group and 129 in controls, for a 34% relative risk reduction. tamoxifen had no effect on the rate of estrogen receptor-negative tumors.

tamoxifen prevented tumors of all grades. importantly, the risk reduction was as great in year 10 as in year 1.

drawbacks of tamoxifen and possible alternatives

long experience with tamoxifen, has shown that it does have drawbacks. the drug is considered to exhibit mixed effects, being antiestrogenic in breast tissue but estrogenic in the endometrium, bones, and liver; and a significant increase in the incidence of endometrial cancer has been consistently seen with its use. tamoxifen is also associated with a significant increase in thromboembolic events, with pulmonary embolism being a particular concern. the related but more selective estrogen receptor modulator (SERM) raloxifene, as well as other SERMs such as toremifene, have also been undergoing evaluation as potentially safer alternatives to tamoxifen.

a relatively recent article (october 2006) at the fabulous resource breast cancer research site states that

placebo controlled trials in over 25,000 women showed that tamoxifen reduced breast cancer risk by about 40% and osteoporotic fracture risk by about 32%. similarly placebo controlled trials in nearly 18,000 women showed that raloxifene reduced breast cancer risk by 44-72% and osteoporotic fractures risk by 30-50%. a direct comparison of tamoxifen with raloxifene showed similar risk reduction for breast cancer and osteoporotic fractures with less toxicity for raloxifene.

other alternatives come from complimentary medicine. that’s a whole difference bowl of wax. perhaps we’ll post about that some other friday.

(image by linda bowman)

Leave a comment

Your email address will not be published. Required fields are marked *