Tuesday, April 18, 2006

Breast Cancer Prevention Trial

This is all over the news, so you may have seen it already: raloxifene, an osteoporosis drug, may also help prevent breast cancer in high risk women and be an alternative to tamoxifen, as it appears to have fewer side effects.

Keep in mind that these are preliminary results of the STAR trial, taken from the NCI release:
  • "The numbers of invasive breast cancers in both groups of women were statistically equivalent."
  • "women in the raloxifene group had 29 percent fewer deep vein thromboses (blood clots in a major vein) and pulmonary embolisms (blood clots in the lung) than women in the tamoxifen group."
  • "The number of strokes occurring in both groups of women was statistically equivalent."
  • "While tamoxifen has been shown to reduce, by half, the incidence of lobular carcinoma in situ (LCIS) and ductal carcinoma in situ (DCIS), raloxifene did not have an effect on these diagnoses. (LCIS and DCIS are sometimes called noninvasive breast cancers.) Of the 9,726 women taking tamoxifen, 57 developed LCIS or DCIS, compared to 81 of 9,745 taking raloxifene."

    Data was available for 19,471 women enrolled in the STAR trial, and "Women who participated in STAR were postmenopausal, at least 35 years old, and had an increased risk of breast cancer as determined by their age, family history of breast cancer, personal medical history, age at first menstrual period, and age at first live birth." The last of the bullet points above is notable, as it is seemingly the only point on which the drugs were not equivalent, or on which raloxifene did not perform better than tamoxifen. Some coverage of the trial also suggests that women who have already been using tamoxifen for several years may not see major benefits from switching.

    National Cancer Institute
    National Cancer Institute: STAR Questions & Answers
    National Cancer Institute - overview of the STAR trial
    New York Times
    Washington Post
    All Things Considered
    NIH News - National Institutes of Health
    Thoughts of An Average Woman - I disagree with her take on the study's validity, that there is no control in the study, because it seems that tamoxifen is the control. This is not an uncommon study design for comparing a new drug or a new use for a drug to one that is more established for a specific purpose. However, you might enjoy her blog anyway.

    Technorati Tags: ; ; ;
    MeSH Tags: Breast Neoplasms/prevention and control; Raloxifene; Tamoxifen

    Anonymous Anonymous said...

    From Houston SelfHelperCourtney CAUTION about this raloxifene-DON'T rush out & get the stuff. the National Women's Health Network issued this news summary--Monday, April 17, 2006, the National Cancer Institute (NCI) announced preliminary results from STAR, a large clinical trial comparing the effect of raloxifene and tamoxifen on the risk of developing breast cancer in postmenopausal women who were considered to be at higher than average risk. The trial was funded by the NCI and Eli Lilly, manufacturer of raloxifene, which is currently marketed under the brand name Evista for prevention and treatment of osteoporosis. According to the NCI, both drugs cut the number of new cases of breast cancer in half, but women taking raloxifene experienced fewer serious side effects such as blood clots and cancer of the uterus. The NCI stressed this benefit in its announcement, stating "For many women, raloxifene's benefits will outweigh its risks in a way that tamoxifen's benefits do not." NWHN is more cautious about the results of the trial, and believes that the breast cancer benefit of raloxifene may only be useful to a very small number of women.

    What do the numbers show?
    The numbers announced by NCI show that raloxifene is somewhat better than tamoxifen (brand name Nolvadex), although not strikingly so. 23 women taking raloxifene developed uterine cancer, compared with 36 women on tamoxifen; and 100 women taking raloxifene experienced serious blood clots, compared with 141 women on tamoxifen.

    These results show that raloxifene is significantly less likely than tamoxifen to cause serious side effects - but we question whether it is likely to make a significant difference in women's lives. Using the numbers released by NCI, we calculate that of the nearly 10,000 women who took raloxifene for up to five years, only about 30 benefited, once the serious risks are taken into account. While some women may appreciate this marginal benefit, question whether this should be viewed as a major advance in preventing breast cancer?

    Consider that the results have not yet been reviewed by experts who weren't involved in the study (a requirement before the research can be published in a major medical journal), nor has the Food and Drug Administration (FDA) examined the records of the study to determine whether the agency will approve raloxifene for breast cancer risk reduction.

    Should women take raloxifene?
    Women who are currently taking tamoxifen to reduce their risk of breast cancer should wait until the results of the STAR trial have been reviewed by the FDA before considering switching to raloxifene. FDA reviewers have access to all the information generated by the researchers and can provide an objective assessment of the results. Women who take bisphosphonates (drugs such as Fosamax, Actonel, Boniva) for osteoporosis also shouldn't rush to switch. While there are still some questions about the long-term effects of bisphosphonates on bone structure, it seems clear that they do not increase the risk of stroke, blood clots or cancer.

    Healthy women who are not at higher than average risk of either breast cancer or osteoporosis should be especially skeptical of any efforts to persuade them to start taking raloxifene. It's very likely that the ultimate results of the STAR trial will show that raloxifene isn't quite as bad as tamoxifen, but it's still not safe enough for most women to use. And we've certainly learned that it's important to wait until enough information is available for women to be able to make truly informed choices. NWHN urges women and their practitioners not to get caught up in the hype, and wait for the facts.

    see the NWHN's full analysis of the STAR trial.

    7:51 PM  
    Blogger Rachel said...

    That's one very long anonymous comment. I'm not sure how I feel about press releases and blog posts in my comments. In any case, it's a good point to keep an eye on who is funding studies. I also agree that it's important to note that these are preliminary results and have not been formally written up and submitted to the rigors of peer review.

    A few things to ponder, on the other hand -- No, the numbers aren't "striking" - the percentages are slightly more so, and any reduction in cancer or clot risk may be important to some women already also at risk for those conditions. It's not clear that this is being touted as a "major advance," at least not by the National Cancer Institute, so I'm not sure where that criticism is coming from. And certainly the FDA will have to approve the drug as safe for that use in order for it to be marketed for that purpose. At that time, the data will be submitted for additional review.

    Finally, I also agree that it's important for women not at an increased risk of cancer (the study looked at women who were) and should make informed decisions rather than decisions based on hype. I'm hesitant, however, to dismiss small advances that may improve the lives of some women as unimportant - this press release has its own fair share of hype, however correct certain points may be.

    FYI - that link didn't work.

    9:05 PM  

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