Reasons young women stop taking tamoxifen vary over time

Looking at a little understood yet common phenomenon—women discontinuing tamoxifen therapy early—French researchers found several factors caused women to interrupt treatment. These factors varied, depending upon when the women stopped therapy.

The study was published in the Annals of Oncology.

Background and reason for the study

Tamoxifen is a medicine used to treat hormone receptor-positive breast cancer, often in premenopausal women. It is given after primary treatments such as surgery and chemotherapy.

Tamoxifen prevents the return of breast cancer by blocking estrogen from reaching estrogen receptors. The standard recommendation is to take tamoxifen for five years, although a major new study now suggests that giving it for 10 years increases benefits.

Although tamoxifen is effective, many women stop taking it before they finish the full treatment course. Some may stop because of common side effects, such as hot flashes, vaginal dryness and mood swings. Others may worry about tamoxifen’s rare side effects, including blood clots and increased risk of uterine cancer. Some women might stop in order to become pregnant, since tamoxifen can damage a fetus.

Other factors also might cause women to stop treatment. The researchers wanted to find out how often young women discontinue tamoxifen and to identify the reasons why.

Study structure

The study looked at 196 women from southeastern France who were 18 to 40 years old at diagnosis. The women, diagnosed from 2005 to 2008, were part of a larger group being studied to learn about their post-treatment lives.

Using pharmacy refill data, the researchers measured how often women stopped tamoxifen treatment. An interruption was defined as two or more consecutive months without dispensed tamoxifen prescriptions.

To determine when the women discontinued tamoxifen, the researchers looked at two time periods:

• From the start of taking tamoxifen to 16 months after diagnosis
• From 16 months to 28 months post-diagnosis

Reasons for stopping tamoxifen were organized according to the treatment time period.

Findings

Within the first two years of treatment, 42 percent of the young women stopped taking tamoxifen.

In the first time period (up to 16 months after diagnosis), interruptions were associated with:

• Lack of information the women could understand about tamoxifen
• Not enough social support

For the second time period (16 to 28 months after diagnosis), interruptions were associated with:

• Side effects
• No longer being afraid of breast cancer returning
• Lack of social support
• Not being able to ask questions at diagnosis
• Fewer types of treatment

The researchers concluded that better communications between women and providers and improved information might help prevent discontinuation of tamoxifen. They also advised healthcare providers to give more attention to women who have little social support.

What this means for you

It can be difficult to think about taking a medicine every day for five or 10 years, especially if you have side effects. Yet tamoxifen can be a key part of your continuing care and staying on it helps prevent a breast cancer recurrence.

If you are having trouble taking tamoxifen, or are thinking about stopping for any reason, talk with your healthcare team before discontinuing. They can offer ways to lessen or eliminate side effects. They also understand the emotional concerns you may be facing.

Your oncologist can answer questions you may have about using tamoxifen or wanting to become pregnant. Your oncology nurse may have suggestions for dealing with side effects and ways to stay on medicine important for avoiding a breast cancer return. You might also find it helpful to talk with an oncology social worker or counselor.

C Cluze, D Rey, L Huiart et al. Adjuvant Endocrine Therapy with Tamoxifen in Young Women with Breast Cancer: Determinants of Interruptions Vary Over Time. Annals of Oncology, 2012; 23(4):882-890.