Efficacy of hormone treatment for breast cancer does not always outweigh side effects

One in six women with breast cancer feels that the effectiveness of endocrine therapy does not outweigh the side effects and the length of treatment. This finding appears in a publication in the journal Annals of Oncology by researchers from Utrecht University, the Netherlands Institute for Health Services Research (NIVEL) and the University Medical Centre and Diaconessenhuis in Leiden.

Five years of treatment with the drug tamoxifen reduces the risk of breast cancer recurring by 41%. Despite the effectiveness, 20 to 25% of women in the United States initially stop taking the drug – a figure that rises to 30 to 40% after a couple of years – because of the side effects or because of doubts about the efficacy. In this Dutch study the researchers therefore attempted to find out how many women felt that the side effects did not outweigh drug efficacy. The idea was that these women would be precisely the women who do not adhere to their treatment regime.
 
Side effects
“By talking to patients, doctors can try to find out what they think and use that information to their advantage,” states Liset van Dijk, the programme leader at NIVEL. “They can do this, for example, by placing additional emphasis on the efficacy and the importance of the treatment.” Although women deem the effectiveness of the hormone treatment to be the key aspect, they are also very apprehensive about side effects such as joint and muscle pain and an elevated risk of endometrial cancer. For one in every six women, the possible side effects of the drug do not outweigh its efficacy. The risk of these women stopping their treatment is therefore higher.
 
Weighing up the pros and cons
“Our research method gives us a better picture of what women really think is important regarding their treatment,” says Hans Wouters, a researcher at Utrecht University. “A great deal of research is being done into patients’ concerns about drugs they have to take. But much less is known about the decisions women take when weighing up the various side effects of a drug against the duration of the treatment and/or its effectiveness. And those decisions are important for determining how satisfied women are with their treatment and will ultimately also affect their treatment adherence.”
 
Hot flushes
The study included 241 women with breast cancer who were receiving hormone therapy. The women were given a selection test in which they could choose between two therapeutic options with differing characteristics. For example, one option would be taking pills for two years with a lot of hot flushes as a side effect, the other option would be five years of pills with only a few such flushes. It is important to note here that one treatment option is more favourable in one respect but less favourable in another respect compared to the alternative therapeutic option. The women therefore genuinely had to weigh up the possibilities. They were each given fifteen such pairs of choices, and based on their answers were subsequently given new options to choose between. This research method has now been applied for hormonal therapy; further studies using this method will follow for the use of antidepressants and cholesterol-lowering drugs.
 
Funding
Netherlands Organisation for Health Research and Development (ZonMW)
 
Cooperating partners
Utrecht institute for Pharmaceutical Sciences
Leiden University Medical Centre (LUMC)
Diaconessenhuis Hospital, Leiden