Hot Flashes May Be a Silver Lining of Breast Cancer Treatment

"Hot flashes are a good sign for women with breast cancer." Did you read that right? If you're living with hot flashes, you know that the sensation is not as pleasant as you may have once pictured it. One woman who described hot flashes as "having her own private summer" must have forgotten about the heaps of laundry that go with these periodic drenchings. Yet we are learning that hot flashes aren't always bad. In fact, they may be a silver lining, predicting that your breast cancer treatment is working or that you are at lower risk than if you weren't having hot flashes with these medications.

Studies are telling us that the "adverse event" of hot flashes—especially if they are intense and occur often—predicts greater survival in people being treated with hormonal therapies for breast cancer such as tamoxifen or the aromatase inhibitor exemestane. And for those who haven't experienced breast cancer but are coping with hot flashes, these moments of flushing (or drenching) may be a positive sign as well.

Let's take a look at what we are learning about hot flashes and other adverse events related to breast cancer treatment, and how you can use this information in a way that may help as you cope with these annoying side effects.

Estrogen, Hot Flashes, and Breast Cancer

In a way, it makes sense that hot flashes might be linked with a lower risk of breast cancer or breast cancer recurrence. We clearly know that estrogen plays a role in breast cancer and hot flashes commonly occur when the ovaries stop producing estrogen during menopause.

With breast cancer, estrogen acts a little like jet fuel, hastening the growth of estrogen receptor-positive breast cancers. When estrogen is blocked (or if the androgens after menopause are not allowed to be converted to estrogen), breast cancer cells essentially run out of gas.

The hormonal medications used for breast cancer often cause hot flashes, but these hot flashes are not the same for each person. Some people are very bothered by frequent hot flashes and night sweats, while others experience little or none of this "adverse reaction." Knowing this, it makes sense that researchers would be interested in finding out whether women who have more severe hot flashes (referred to by healthcare providers as "vasomotor symptoms") respond better to these treatments.

Hot Flashes, Breast Cancer Treatment, and Survival

Several studies between 2012 and 2016 have looked at whether hot flashes may be a sign that someone will respond better to certain hormonal treatments, and also, whether women who have more severe hot flashes are more likely to develop breast cancer in the first place.

Though we know that hot flashes are linked to a decrease in estrogen in the body, we don't know exactly how or why they occur. In other words, we aren't certain whether low estrogen levels contribute to both hot flashes and the growth of breast cancer, or if there are other mechanisms underlying both processes.

Hormone Treatments for Estrogen Receptor Positive Breast Cancer

Before we talk about the predictive value of hot flashes with some breast cancer drugs, it's helpful to briefly mention the drugs we are talking about, those which are considered hormonal therapy (or endocrine therapy) for breast cancer.

Simplistically, there are two primary types of hormonal therapies used to treat estrogen receptor-positive breast cancer.

• Selective estrogen receptor modulator (SERMs) such as tamoxifen—Tamoxifen works by blocking the ability of estrogen to bind with breast cancer cells and cause them to grow. In premenopausal women, the ovaries continue to make estrogen and a drug like tamoxifen is needed.
• Aromatase inhibitors (AIs): AI's are drugs which are used in postmenopausal women (or premenopausal women who have been treated with ovarian suppression therapy or had their ovaries removed) to prevent the synthesis of estrogen in the body. They do this by blocking the conversion of androgens to estrogens, a reaction catalyzed by enzymes called aromatases. Drugs classifed as aromatase inihbitors include Arimidex (anastrozole), Aromasin (exemestane) and Femara (letrozole).

Both tamoxifen and aromatase inhibitors significantly reduce the risk of breast cancer recurrence. In addition, and unlike chemotherapy, they reduce the risk of late recurrences, or recurrences that occur 5 or more years after diagnosis. This is important as early stage estrogen receptor positive breast cancers are more likely to occur after 5 years than in the first 5 years, and the risk of recurrence remains constant each year for at least 20 years.

Exemestane, Hot Flashes, and Breast Cancer Treatment Response

A study performed in 2012 looking at women taking exemestane found that those who had hot flashes during treatment had a significantly increased relapse-free survival rate. Another study in 2016 looking at postmenopausal women being treated with exemestane yielded similar results. The women who had vasomotor effects (hot flashes and night sweats) were much more likely to respond to exemestane treatment than those who did not have these symptoms (70 percent vs 40 percent.) In contrast, there was no difference in the response rate to the drug among those who did or did not have muscle aches or joint pains. In this study, a response to exemestane was defined as a 30 percent or greater reduction in tumor size on imaging studies.

Tamoxifen (or Exemestane), Hot Flashes, and Breast Cancer Survival

A 2013 study looked at over 9,000 women who were treated with either tamoxifen or exemestane. Those who had hot flashes had better disease-free survival (by 27 percent), overall survival (45 percent higher) and fewer distant metastases (19 percent less chance that their breast cancers would spread to distant organs such as the brain, lungs, liver, or bones.)

In this study (unlike the study above), women who had muscle and joint aches, as well as those who had vulvovaginal symptoms were more likely to survive than women who did not have these symptoms.

Hot Flashes and the Risk of Developing Breast Cancer

Though it makes sense in a way that people who have hot flashes would be less likely to develop breast cancer; it wasn't until fairly recently that studies found this to be true.

A 2011 study found that women who had hot flashes were only about half as likely to develop breast cancer than women who had not experienced any hot flashes. Women with hot flashes were 50 percent less likely to develop invasive ductal carcinoma of the breast and 50 percent less likely to develop invasive lobular carcinoma of the breast. In addition, it was found that the more often hot flashes occurred, and the more intense they were, the greater reduction in breast cancer risk.

Yet another study one in 2013 found that women who had experienced hot flashes (and other menopausal symptoms) had only half the risk of developing young-onset breast cancer (defined as breast cancer before the age of 50) than women who had not experienced these symptoms.

The Link Between Hot Flashes and Breast Cancer 

Though all of these studies have found a link between hot flashes and a better response to hormonal treatments for breast cancer (or less risk of developing breast cancer) we still aren't certain exactly how these are connected or how this occurs.

Help for Hot Flashes

Hot flashes aren't fun and they don't do much to improve the quality of life for many women living with breast cancer. Thankfully, research is looking into methods of improving these symptoms (while avoiding estrogen.)

A word of caution is in order for those who are considering alternative treatments such as herbal preparations in order to cope with hot flashes. Some supplements such as soy contain "phytoestrogens," plant-based estrogens with estrogen-like properties. Since estrogen is used as a fuel for breast cancer cells in people with estrogen receptor positive tumors, many scientists recommend staying clear of soy-based supplements until we know more.

Effexor is an antidepressant that may help with hot flashes for some women, and unlike some of the antidepressants, does not appear to have the same interaction with tamoxifen. Neurontin (gabapentin) is a seizure medication that may help reduce hot flashes. It is also often used to treat neuropathy and neuropathic pain which some people develop on breast cancer chemotherapy.

A study at the Mayo Clinic presented at the 2018 San Antonio Breast Cancer Symposium found that the medication Ditropan or Oxytrol (oxybutynin) ordinarily used for urinary incontinence reduced hot flashes related to breast cancer and improved quality of life. Ditropan does not appear to interfere with tamoxifen metabolism, but its use for hot flashes is considered "off label."

While vitamin E has been touted by some, the type of vitamin E is very important, as some types of vitamin E may cancel out the benefits of chemotherapy. In contrast, one form referred to as tocotrienols may actually potentiate the effect of tamoxifen on estrogen receptor-positive breast cancer cells.

Before considering any supplement, make sure to talk to your healthcare provider. We know that there are some vitamin and mineral preparations that may interfere with cancer treatments.

Some people have found acupuncture to be helpful with hot flashes, but again, talk to your healthcare provider. Some of the best ways to manage hot flashes are very simple.

A Word From Verywell 

The bottom line of the studies looking at hot flashes during breast cancer treatment (at least treatment with hormonal medications) is that these hot flashes may have a silver lining. Knowing this won't necessarily make your hot flashes any more tolerable, but this may be a way to use reframing to help you cope.

Reframing is a process in which you basically look at a situation from a different angle. For example, instead of focusing on the loss of your hair during chemotherapy and how that makes you feel, you might instead find a silver lining—you don't have to shave your legs for several months. Certainly, that is stretching it a bit, but the next time you have a hot flash you may want to picture the hot flash chasing off any breast cancer cells which may be lingering in your body. In that way, at least your "private summer" has a silver lining.