Women with breast cancer who report side effects due to their hormone therapy drugs and also less confident communicating with their doctors are more likely to intentionally or unintentionally skip a dose, says a new study.
The authors wrote in "The Breast" that endocrine therapy, which is given as a daily tablet to prevent hormones from helping tumor to grow, is an important part of the treatment for some types of early breast cancer. But many women do not stick to the medications over time.
"We were surprised that so many women admitted to non-adherent medication-taking behaviors," said lead author Gretchen Kimmick of Duke Cancer Institute at Duke University Medical Center in Durham, North Carolina.
"There are many reasons that women may choose not to take the medicine. The most common reason is probably because they notice side effects," said Kimmick.
The researchers studied 112 postmenopausal women with early stage, hormone-receptor positive breast cancer who had completed surgery, chemotherapy or radiation and were currently taking an endocrine therapy medication like tamoxifen.
The side effects of endocrine therapies are nausea, headaches and hot flashes.
The study participants answered the survey questions about their level of general pain, fatigue, hot flashes or night sweats and nerve pain.
They were also asked to rate their confidence in their ability to take the medicine as prescribed, their ability to communicate with their doctors, beliefs about hormone therapy and their medication behavior.
Women rated from "never" to "very often" the frequency with which they forgot to take medication, skipped doses, or reduced or stopped medication when feeling better or when feeling worse.
The participants have been receiving endocrine therapy for about three years. More than half claimed that they had missed some doses unintentionally, due to reasons like a busy day, away from home or problems getting refills.
About one third of the participants said that they intentionally skipped or changed the dose, because they felt worse or had side effects and sometimes because of cost.
The researchers also found that women with less confidence in taking their medications and less confidence talking with their doctors were more like to miss doses.
Colin McCowan, professor of health informatics at the University of Glasgow, who wasn't involved in the study, said, " Women might not usually receive advice, support and monitoring for adherence during endocrine therapy. Failing to take these drugs as directed increases the risk of cancer recurrence, death, lower quality of life and also higher health service costs."
In the UK, about 70 percent of postmenopausal women with breast cancer are prescribed endocrine therapy, which blocks cancer cells from growing again after chemotherapy or surgery. But, only half of women complete their five-year course of endocrine therapy said McCowan.
"The side effects can cause huge disruption to women's lives and women who don't understand the benefits of the medicines may be less motivated to take them," said McCowan.
Patients should have regular conversation with their doctors about taking endocrine therapy and its side effects and also incorporate the pills in their daily routine to help them stick to the medication, he added.