Should Breast Cancer Survivors Extend Hormone Treatment? Latest Study Says No

Patient Expert

One of the most difficult decisions for a vast number of breast cancer survivors just became a whole lot easier.

Thanks to results of an Austrian study presented Dec. 7, 2017, at the prestigious San Antonio Breast Cancer Symposium, there’s a chance that at least some women can cease hormone therapy without impacting their chances of survival.

How hormone therapy works

According to the American Cancer Society, about 70 percent of women with breast cancer have hormone-receptive cancer (also known as ER/PR+). This means the cancer relies on female sex hormones to grow and thrive. Deny cancer cells access to those hormones, and they die.

Hormone therapy works by either blocking cancer cells’ hormone receptors, so they can’t bond with circulating hormones, or by dramatically reducing the amount of sex hormones a woman’s body produces. Either way, this lack of hormones works to prevent cancer recurrence.

Hormone therapy has been a gold-standard treatment for upwards of 40 years. But for all that time, doctors have never been sure how long the optimum course of therapy should be. Over time, that optimum course had been extended from a couple of years, to five years, then seven, and finally a full 10 years.

So, if 10 years of hormone therapy reduces cancer risk, why bother to study other options?

Because all hormone therapy comes with serious health risks and side effects, ranging from blood clots to another cancer to debilitating bone pain and osteoporosis. Additional side effects can include hot flashes, mood swings, vaginal dryness, painful sex, and hair loss.

Survivors receiving hormone therapy have always had to weigh these difficult side effects against the benefits provided by any of the four main hormone therapy drugs: tamoxifen for premenopausal women; and anastrozole, letrozole, and exemestane for post-menopausal women.

But the results of the new study presented at the San Antonio Breast Cancer Symposium show that at least some women may be able to discontinue hormone therapy sooner.

The study

The ABCSG-16 trial, which focused specifically on the drug anastrozole, indicates that the disease-free survival rate for post-menopausal women extending hormone therapy for a full five years (after an initial five-year course) is no higher than that for women extending therapy for just two years.

Translation? Seven years of anastrozole is as good as 10. So a survivor can eliminate three years of hormone treatment — and its potentially ruinous side effects — without feeling she’s risking her life.

A study presented last year at this same symposium yielded somewhat similar results for the other most common post-menopausal hormone drug: letrozole. Women taking letrozole for just five years versus those taking it for 10 years did have a slightly lower survival rate (91 percent compared with 95 percent). But doctors agree that this small benefit is outweighed by the significantly increased risk of osteoporosis, fractures, and other dangerous side effects that come with taking letrozole.

The bottom line

Have you been on hormone therapy for five to seven years, and now you are wondering if it’s OK to quit? Speak with your doctor. Some women love the feeling of security cancer treatment offers, and might be afraid to quit. Some women aren’t experiencing active side effects, and might decide the risk of bone loss is preferable to fearing the return of cancer.

But if you’re a woman suffering from serious side effects that negatively affect your lifestyle, or if you fear fractures and bone loss more than a very slight chance of cancer recurrence, then stopping hormone therapy may be an option to consider.

See more helpful articles:

Hormone Therapy for Breast Cancer

Anastrozole and Hair Loss: A Surprising Side Effect

Aromatase Inhibitors: A Silent, Potentially Deadly Side Effect

Understanding Hormone Therapy Drugs