Not Taking Hormonal Therapy as Prescribed Leads to More Recurrence
Post-menopausal women who stop taking hormonal therapy early or skip doses are much more likely to have a breast cancer recurrence than women who take hormonal therapy as prescribed, according to a study.
The research was published online on May 23, 2016 by the Journal of Clinical Oncology. Read the abstract of “Treatment Adherence and Its Impact on Disease-Free Survival in the Breast International Group 1-98 Trial of Tamoxifen and Letrozole, Alone and in Sequence.”
Why hormonal therapy?
After surgery, women diagnosed with early-stage, hormone receptor-positive breast cancer usually take hormonal therapy medicine to reduce the risk of the cancer coming back (recurrence).
Tamoxifen and the aromatase inhibitors are the two most common hormonal therapy medicines used to treat early-stage, hormone receptor-positive breast cancer after surgery.
Most women take hormonal therapy for 5 to 10 years after breast cancer surgery.
Both tamoxifen and aromatase inhibitors can cause side effects. Tamoxifen may cause hot flashes and increase the risk of blood clots and stroke. Aromatase inhibitors may cause muscle and joint pain. Less common but more severe side effects of aromatase inhibitors are heart problems, osteoporosis, and broken bones. Research has shown that about 25% of women who are prescribed hormonal therapy to reduce the risk of recurrence after surgery either don’t start taking the medicine or stop taking it early, in many cases because of side effects.
About the study
In this study, the researchers analyzed information that was collected as part of the BIG 1-98 study that was open from 1999 to 2003. The BIG 1-98 study was designed to see which hormonal therapy treatment was most effective for post-menopausal women diagnosed with early-stage, hormone receptor-positive disease:
five years of Femara alone
five years of tamoxifen alone
two years of tamoxifen followed by three years of Femara
two years of Femara followed by three years of tamoxifen
To do this study, the researchers analyzed information on persistence and compliance for 6,144 women in the BIG 1-98 study:
“persistence” is how long the women took the hormonal therapy; all the women were prescribed hormonal therapy for 60 months -- any woman who took hormonal therapy for at least 54 months was considered to have completed the full course of treatment
“compliance” is how consistent the women were in taking the hormonal therapy; the women were given treatment packs every 6 months -- any woman who took at least 80% of the pills during each 6-month period and took no treatment breaks that were 7 days or longer was considered to be compliant with treatment
The researchers wanted to see if women who were considered persistent and compliant had better disease-free survival than women who were not persistent and compliant.
Disease-free survival was defined as how long the women lived without the cancer coming back or a new cancer being diagnosed in the opposite breast.
The women were evenly split among the different hormonal therapy treatments:
1,541 women received five years of Femara
1,535 women received five years of tamoxifen
1,541 women received two years of tamoxifen followed by three years of Femara
1,527 women received two years of Femara followed by three years of tamoxifen
Overall, about 19% of the women didn’t complete the prescribed course of hormonal therapy.
The percentages of women who didn’t complete the prescribed course of therapy by treatment type were:
17.5% of women prescribed five years of Femara didn’t complete treatment
17% of women prescribed five years of tamoxifen didn’t complete treatment
21% of women prescribed two years of tamoxifen then three years of Femara didn’t complete treatment
20% of women prescribed two years of Femara then three years of tamoxifen didn’t complete treatment
Women who stopped taking hormonal therapy early were 35% to 56% more likely to have a recurrence than women who didn’t stop taking the medicine early.
Overall, 5.1% of the women were not compliant with hormonal therapy.
The percentages of women who weren’t compliant by treatment type were:
4.5% of women prescribed five years of Femara weren’t compliant
5.7% of women prescribed five years of tamoxifen weren’t compliant
5.2% of women prescribed two years of tamoxifen then three years of Femara weren’t compliant
5.3% of women prescribed two years of Femara then three years of tamoxifen weren’t compliant
Women who weren’t compliant with hormonal therapy were 61% more likely to have a recurrence than women who were compliant.
Most of the women who stopped taking hormonal therapy early -- about 83% -- said they stopped taking the medicine because of side effects. Women who took Femara then tamoxifen or tamoxifen then Femara were more likely to stop taking hormonal therapy early.
Joint pain was the most common reason women stopped taking Femara early. Blood clots were the most common reason women stopped taking tamoxifen early.
Women were more likely to stop treatment early if they:
were older
smoked or were former smokers
had been diagnosed with node-negative disease (no cancer cells were found in the lymph nodes)
had a history of blood clots
switched from one hormonal therapy to the other
What this means for you
If you’re a post-menopausal woman who’s been diagnosed with hormone receptor-positive breast cancer and will be taking hormonal therapy after surgery and other treatments, it’s very important that you take the medicine for as long as it’s prescribed and at the dose at which it is prescribed. Hormone receptor-positive breast cancer can come back and hormonal therapy after surgery reduces that risk -- you must remember that.
Side effects caused by hormonal therapy can be very troublesome for many women. It’s important to talk to your doctor as soon as you start having any side effects, including hot flashes, joint pain, blood clots, trouble sleeping, fatigue, or difficulty concentrating. Don’t wait until the symptoms are intolerable and you have to stop taking the medicine. There are steps you can take to ease these side effects, including switching to a different type of hormonal therapy.
— Last updated on October 18, 2023 at 6:13 PM