Expert: Endocrine therapy for breast cancer is hard but effective

"Endocrine therapy increases survival. It can reduce your risk of a recurrence (cancer coming back) by 40% and up to 75% in certain subgroups of people," says Anna Weiss. (Credit: Getty Images)

An expert offers insights and advice regarding the benefits and side effects of endocrine therapy for breast cancer.

Cancer treatment is riddled with pros and cons, trade-offs. During October, breast cancer awareness month, the spotlight shines on endocrine therapy or “hormonal therapy.” The drug, Tamoxifen, and others like it that shut down estrogen, are well-known in this category among breast cancer survivors.

Why don’t people want to take it?

The majority of individuals diagnosed with breast cancer will need to stay on this medication for five to 10 years after surgery—and yet for some people, side effects (hot flashes, vaginal dryness, bone loss, and joint pain) make it difficult to follow that recommendation. More than 30% of patients stop taking endocrine therapy early and many don’t take it as prescribed, despite its life-saving benefits.

Wilmot Cancer Institute’s Comprehensive Breast Care program leader, Anna Weiss, recently discussed in national articles and podcasts why it’s so hard to adhere to this treatment. She is senior author of a publication in Annals of Surgical Oncology this year on the topic.

Weiss outlines the issue below:


What is endocrine therapy?


It’s a medication that blocks the effects of estrogen on tissue and reduces the chances of cancer recurrence. You might hear it being called “hormonal therapy.” It typically involves taking a daily pill, but can also be an injection or a liquid. (In addition to Tamoxifen, some common brand names include Faslodex, Arimidex, or Femara.)

Some women get endocrine therapy in addition to chemotherapy, and some instead of chemotherapy. It just depends on how advanced their cancer is.

This treatment is used for estrogen-sensitive cancers. About 80% of all breast cancers fall into this category and are hormone-receptor positive, so they respond well to this therapy.

Endocrine therapy increases survival. It can reduce your risk of a recurrence (cancer coming back) by 40% and up to 75% in certain subgroups of people.


How long is endocrine therapy? Why do some patients need to stay on it for years?


Research has shown the benefits of taking endocrine therapy for many years—but the benefit may be different for different groups of patients. For example, patients who are pre- or post-menopausal may benefit from different drugs, and from different lengths of time for treatment. Some patients will take just one medication, and others will take a combination.

Commonly, the therapy is taken for five years, but for patients at a slightly higher risk of cancer returning, doctors may recommend 10 years of treatment.

The bottom line: clinical research has been extensive, and clearly shows that staying on endocrine therapy for a minimum of five years and up to 10 years provides the most protection from cancer returning. It’s best to talk to your medical oncologist about what the evidence shows for specific cases like yours.


What are the side effects of endocrine therapy?


When we recommend endocrine therapy, side effects are the biggest fear. The medicine kind of gets a bad rap. Most people are afraid of the hot flashes. We call those vasomotor symptoms.

Sometimes, there’s also memory loss, like when you go through menopause, and that can happen with the medication, too.

Joint aches and stiffness are other symptoms. Some patients are already dealing with arthritis, perhaps at their age, and so that’s an added problem. Another thing is bone loss. With Tamoxifen, there’s a 5% increase in the fracture rate over five years. With some other medications, it’s an 8% increase in fracture rate. That’s not that high, but it’s not insignificant, either. And this population is often dealing with osteopenia and osteoporosis (bone loss) anyway.

The other things we hear about are genitourinary syndrome of menopause, or GSM. GSM is kind of a new phrase, and it’s gaining attention by patients and health care providers. The symptoms encompass vaginal dryness, vaginal atrophy, painful sex. It’s because the skin thins due to a lack of estrogen. It’s common as you age and become post-menopausal, and the treatment can make things worse. A lot of survivorship experts in breast cancer are trying to tackle this problem.


How can the side effects be managed?


For GMS, there are four simple things you can do. First, avoid irritants. You don’t want to douche or use sensory things with flavors or anything like that. Get rid of all of it.

Second, you want to moisturize with very simple, bland stuff, like coconut oil. Third, lubricate, always, when having sex. And last, talk to your gynecologist about other things you can do to help your actual anatomy, like pelvic floor exercises.

For hot flashes, from the literature we know that 30% to 50% of patients get them from endocrine therapy. I’m guessing it’s closer to 50%. For most people, behavioral changes can give some relief, such as dressing in layers and putting fans on you at night. There are easy-to-tolerate medicines, such as oxybutynin, that can help. There are also some other really easy therapies, like acupuncture, exercise, yoga, and meditation.

For brain fogginess, I’m a surgeon and so I don’t hear about that as much. But I do know that when it’s bad, it can be very bad in terms of being able to work and perform your job.

(Wilmot scientists have conducted research on cognitive problems, mostly related to chemotherapy. In several clinical studies, however, many participants are also taking endocrine therapy. Research concludes, in general, that being physically active can help with a variety of side effects stemming from breast cancer and its treatment—including brain fog, pain, and fatigue, according to Michelle Janelsins, a senior investigator in Wilmot’s Cancer Prevention and Control program. The American College of Sports Medicine has also published evidence-based exercise guidelines for cancer survivors saying that “every survivor should avoid inactivity” and recommends consulting with health care providers about an exercise plan.)


Talk about the risks-versus-benefits of endocrine therapy.


There are many studies that center on endocrine therapy, adherence, and discontinuation. The discontinuation rate is around 30%. That doesn’t sound like a lot, but when you think about how it’s a life-saving medication, 30% is pretty high.

All treatment is optional, and there are trade-offs. It’s important to talk your doctor about the benefits. Demystifying and destigmatizing all of this is what’s really important.