In this randomized trial—the first test of breast cancer chemoprevention DA since the STAR trial— we discovered that women who received a tailored DA that described the risks and benefits of tamoxifen and raloxifene had very little interest in taking either drug. Immediately after reviewing the DA, only 6% of women said they were likely to take tamoxifen or raloxifene, and three months later, less than 1% had begun taking either drug.
Although previous studies have shown that women’s perceptions of the risks of tamoxifen are a significant factor in their reluctance to utilize chemoprevention, [5
our study showed only moderate concern regarding the medications’ side effects. Furthermore, participants who viewed our DA had fewer concerns about the side effects than did those who did not receive the DA.
Instead, women seem to be reluctant to take chemoprevention drugs because they perceive that the drugs do not substantially lower their risk of breast cancer. Our results show that even after learning that their relative risk will decrease by 50% if they took either drug, less than half of women perceive that they will experience any decrease in their own breast cancer risk. Women’s perceptions of the low benefit of taking tamoxifen or raloxifene may have also been influenced by the fact that for the majority of the women their 5-year risk was 3% or lower. Thus, their risk of breast cancer might have felt very low, especially compared to their risk of side effects. Additionally, women’s risk of breast cancer may have felt low given that they are accustomed to hearing the average woman’s lifetime risk of 13%. Compared to 13%, 3% may seem like a very small risk, particularly if one fails to notice the different time intervals (i.e., 5-year risk vs. lifetime risk). Combined, these factors may have led women to view their risk of breast cancer as so low that they do not need a preventive medication that is accompanied by significant side effects.
We should note that our goal in the design of our DA was not to convince women to take chemoprevention. Rather, we designed the Guide to Decide to present information in a neutral manner so that participants could decide, for themselves or with their doctors, whether chemoprevention was a good option.
Our study has several limitations. First, our sample consisted mostly of White women. Low recruitment of African American women has plagued other studies[5
] including the NSABP P-1 trial of tamoxifen [16
] and the STAR trial.[12
] A second limitation was the use of an online DA. While web-based DAs can ultimately increase intervention reach, this modality limits participation to those with Internet access. Third, our sample included only women with health care coverage. These limitations led to a relatively educated sample and a low response rate. In fact, we believe that among the primary reasons for our low response rate was lack of Internet access or lack of comfort with using the Internet (potentially reducing the participation of lower income or lower educated individuals). Other reasons for our low response rate may include lack of interest in the topic or lack of time to complete a study that was 30-60 minutes long. Thus, our findings may not be generalizable to women of other racial and ethnic groups or less educated or economically-disadvantaged women. That said, we would expect our sample to be biased in favor of women who are more likely to consider using chemoprevention, since they were an insured population with pharmacy benefits.
While the above limitations limit the external validity of our study, the inclusion of control groups significantly strengthen the internal validity. Inclusion of the Time 1 control group allows for a test of our DA compared to not receiving any information about tamoxifen and raloxifene. Furthermore, inclusion of the 3 month control group allows for an untarnished control for participants behavior over the 3 month time period.
The results of this study show clearly that many women at moderately higher risk of developing a first breast cancer nevertheless have little interest in chemoprevention, even after exposure to a tailored DA. Moreover, the inclusion of raloxifene in our DA, following completion of the STAR trial, did not lead to greater interest in chemoprevention. Adding “the bone drug,” in other words, did not lead informed women to seek out prescriptions from their physicians.
Given the robust literature that has shown that women have significant concerns regarding the use of tamoxifen[22
], and numerous studies demonstrating that that they do not believe that the benefits outweigh the risks of chemoprevention,1,4
it appears that women will not be interested in breast cancer chemoprevention until they perceive a significant change in the risks or benefits of such drugs.