CBD oil can’t treat or cure breast cancer, but it may ease side effects of treatment like pain, anxiety, insomnia, nausea, and vomiting. Here’s what to know about using CBD oil for breast cancer. Effect of combining CBD with standard breast cancer therapeutics Breast cancer is the most common malignancy in women worldwide. Sixty-five percent of breast cancers are estrogen and/or
CBD Oil and Breast Cancer
If you’re being treated for breast cancer, you’ve probably had some side effects like pain, fatigue, nausea, discomfort, and anxiety. Maybe you’ve heard other people with the disease talk about using CBD products to ease these symptoms — or you’ve run across CBD at your local gas station or drug store. But what exactly is CBD? How does it work? And can it really help people who have breast cancer?
Defining the Terms
First, let’s break down the terms, which can be confusing.
- Cannabis is a type of flowering plant that has more than 500 chemicals. Hemp and marijuana are both forms of cannabis.
- Tetrahydrocannabinol (THC) might be the best-known chemical, known as a cannabinoid, in the cannabis plant. Its psychoactive ingredients create intoxication, or a “high.”
- Cannabidiol (CBD) is another well-known chemical in cannabis. Even though it’s also technically considered psychoactive, CBD is not intoxicating because it affects the brain differently than THC. CBD that’s extracted from hemp is federally legal, but it’s not legal in every state. CBD can also be extracted from marijuana.
- Hemp is any cannabis plant that contains mostly CBD and has a maximum of 0.3% THC. The 2018 Farm Bill made it legal to grow industrial hemp in the United States.
- Marijuana is any cannabis plant that has more than 0.3% THC, an amount that causes a high. It contains various amounts of CBD. Marijuana is not federally legal, and its legality varies from state to state.
How CBD Can Help
Your body has a natural endocannabinoid system, “a complex network of receptors on cells that regulates your daily body functions, such as inflammation, mood, and sleep,” says Marisa C. Weiss, MD, chief medical officer and founder of Breastcancer.org and director of breast radiation oncology at Lankenau Medical Center in Wynnewood, PA.
CBD works by interacting with this system, which means it can help reduce side effects of breast cancer treatment like pain, anxiety, insomnia, nausea, and vomiting.
That said, it’s important to note that there is no evidence that CBD can treat or cure breast cancer itself.
“As a doctor, I make the distinction between complementary and alternative medicine,” says Andrea Mathias Schmucki, MD, a patient advocate for the Living Beyond Breast Cancer Hear My Voice advocacy program and a former family physician. She is herself being treated for metastatic breast cancer, or cancer that’s spread to other parts of her body. “I look at CBD as complementary, using it in addition to, rather than as an alternative to, traditional treatment.”
Before she had a double mastectomy, reconstruction surgery, chemotherapy, and radiation for breast cancer in 2015, Mathias Schmucki says, she wouldn’t have put much stock in something like CBD (though she would have supported her patients’ choice to use it). But ibuprofen wasn’t relieving the itchy, scratchy, painful sensations she was having. She was so uncomfortable, “I was open to anything.” She knew that she didn’t need or want the mind-altering effects THC can create, so she decided to try CBD oil.
She bought some at her local pharmacy and took it by mouth every day for a month, noticing that it seemed to help on some days. But she wasn’t convinced that the changes were due to the CBD oil, so she didn’t get more when it ran out. Within 3 weeks, the horrible discomfort was back. She researched CBD in-depth and found a reputable company. Now, she’s a believer. “It has made a significant improvement in my daily quality of life,” she says.
How CBD Is Used
Weiss notes that there are all kinds of CBD products beyond oil, such as edibles, capsules, tinctures, creams and oils for skin, and sprays that you can use under your tongue.
Mathias Schmucki still takes CBD oil orally. She also uses a topical CBD oil for the skin on her radiation-treated side to help with the dryness and discomfort, plus a CBD extract in a coconut-oil-based suspension as a personal lubricant for intercourse. “A lot of women with breast cancer experience sexual side effects because one of the mainstays of treatment is anti-estrogen,” she explains.
Side Effects and Risks
According to Weiss, some people who use CBD have reported side effects including:
- Drowsiness and fatigue
- Less appetite
Mathias Schmucki notes that there aren’t a lot of studies on the potential risks of CBD oil, so it’s not clear exactly what they might be. However, “CBD is usually well-tolerated,” Weiss says.
Weiss offers these cautions:
- Don’t use cannabis products if you’ve had a heart attack within the past 6 months or if you have severe heart disease.
- Some medications can have a negative interaction with cannabis products, such as warfarin (Coumadin, Jantoven). Give your doctor and pharmacist a complete list of all the medications and supplements you’re taking so they can keep an eye out for interactions.
- Watch out for product ingredients that you might be allergic to, like coconut oil.
- It’s best to steer clear of cannabis products altogether if you’ve had serious side effects from using them before, like uncontrolled vomiting.
- Be aware that many CBD products may contain trace amounts of THC that can show up on a drug test. Check your employer’s medical cannabis policy before you use CBD.
Talking to Your Doctor
Weiss and Mathias Schmucki agree that it’s critical to talk to your doctor before you use CBD, especially if you’re in active treatment for breast cancer. For one thing, you need to make sure it’s a safe option for you.
If you’re taking certain medications like blood thinners and thyroid and seizure medications, you’ll need periodic blood tests to make sure your levels are where they should be. If you’re on a medication like this and you’re going to use CBD products, Mathias Schmucki says, your doctor will need to monitor you to make sure your levels stay on track. “Everybody’s different, so you won’t really know how CBD will affect your body’s metabolism of other medications,” she says.
Your doctor may not be enthusiastic about you using CBD, but that doesn’t necessarily mean they’re resistant to the idea. “Remember that your doctor wants to help manage your symptoms and pain, so being open and honest about what you need is the best way to communicate,” Weiss advises.
If you’re having breast cancer treatment side effects or symptoms that aren’t being controlled, or if you think your doctor isn’t listening to your needs or doesn’t have the experience to give you advice on CBD products, get a second opinion, Weiss suggests. She recommends talking to an oncologist who is knowledgeable about cannabis products if your doctor can’t help.
“I tell my doctors that I’m not holding them responsible for my decision to use CBD, but I want them to know this is a choice I’m making,” Mathias Schmucki says. “I’m giving them information they need to provide the best care that they can.”
How to Buy CBD
What should you look for if you decide to give CBD products a try?
- Medical-grade CBD products. “Just because CBD products made from hemp are now widely available, you shouldn’t assume they’re safe, effective, or even legal where you live, since some state laws still consider hemp CBD illegal,” Weiss says. She recommends looking for medical-grade CBD products because they’re “probably a safer option.”
- Certificate of analysis. Weiss recommends asking for a certificate of analysis (COA) from the company or dispensary you use. A COA comes from a third-party laboratory and tells you the quantity of cannabinoids in the product so that you know exactly what you’re getting. Some COAs also show the levels of potential toxins like pesticides, arsenic, and heavy metals.
For Mathias Schmucki, finding a company that provided a COA with all this information was a must. She says there are several online companies that send it with every product. “The companies with the best reputations will often have very robust websites with educational resources,” she says, so look for these.
Mathias Schmucki says other options, like how the CBD is extracted or what the best delivery method is, are a matter of personal choice.
Keep this in mind, too: “Everyone reacts differently to cannabis products, so don’t feel discouraged if your symptoms aren’t reduced with the first product you try,” Weiss says. “You may need to test different products to find what’s best for you, including the delivery method and dosage.” She suggests starting low and slow, making changes as you go.
“There’s a lot of information out there, but I think you really have to be careful about where you get that information,” Mathias Schmucki says. She advises looking to see if your local medical center has an integrative oncology department that includes nontraditional therapy like CBD and can give you guidance. Other good resources include pharmacists trained in cannabis, experts at medical cannabis dispensaries, and pain management doctors, Weiss says.
Mathias Schmucki has also found that talking to other people who currently have or previously had breast cancer is invaluable. A private Facebook group called Fighting Breast Cancer with Cannabis has been helpful in her own journey.
The Future of CBD
“Research on medical cannabis products, including CBD oil, has been limited because federal laws in the United States have made it difficult to study,” Weiss says. But now that hemp production is legal, it can be studied, Mathias Schmucki notes. “Lifting federal regulations off of the growing and scientific study of cannabis plants will help over time in answering some of these questions about areas like safety, dosing, and contraindications,” she says.
“In the meantime, more research is being done to provide better answers,” Weiss says. For example, she’s the principal investigator on a research team at Lankenau Medical Center that’s testing CBD in cancer patients with chemotherapy-induced peripheral neuropathy (CIPN). This is the first and only FDA-approved CBD study for patients with CIPN, “a common and difficult side effect of the most commonly used chemotherapies, which can damage the nerves and lead to pain, discomfort, or numbness, most often in the hands and feet,” she explains.
Johns Hopkins Medicine: “Side Effects from Breast Cancer Treatment.”
Marisa C. Weiss, MD, chief medical officer and founder, Breastcancer.org; director of breast radiation oncology, Lankenau Medical Center, Wynnewood, PA.
National Center for Complementary and Integrative Health: “Cannabis (Marijuana) and Cannabinoids: What You Need to Know.”
PBS NewsHour: “Is CBD legal? Here’s what you need to know, according to science.”
Project CBD: “Is CBD Really Non-Psychoactive?”
U.S. Department of Agriculture: “Hemp and Farm Programs.”
Breastcancer.org: “Medical Cannabis.”
Andrea Mathias Schmucki, MD, patient advocate, Living Beyond Breast Cancer Hear My Voice advocacy program.
Citizen Truth: “What is a CBD Certificate of Authenticity (COA) (And How to Read It).”
Effect of combining CBD with standard breast cancer therapeutics
Breast cancer is the most common malignancy in women worldwide. Sixty-five percent of breast cancers are estrogen and/or progesterone receptor positive. Estrogen receptor expression is a prognostic and predictive biomarker of response to endocrine therapy, which consists of the selective estrogen receptor modulator tamoxifen, aromatase inhibitors, and the selective estrogen receptor degrader fulvestrant. Cannabidiol is a phytocannabinoid that is emerging as a potential therapeutic agent. The aim of this study was to investigate the effect of cannabidiol on estrogen receptor-positive and estrogen receptor-negative representative breast cancer cell lines in combination with standard therapeutic agents used in clinical practice. To compare the effects of cannabidiol on breast cancer cell viability, cancer cell lines were exposed to increasing concentrations of cannabidiol. The effects of cannabidiol in combination with the endocrine therapeutics tamoxifen, fulvestrant, and the cyclin-dependent kinase inhibitor palbociclib on breast cancer cell viability were examined. We demonstrated that cannabidiol dose-dependently decreased the viability of all breast cancer cell lines independent of estrogen receptor expression. The addition of cannabidiol to tamoxifen had an additive negative effect on cell viability in ER+ in estrogen receptor positive T-47D line. Cannabidiol did not attenuate the effect of standard treatment of hormone receptor-positive breast cancer with fulvestrant and palbociclib. In addition, cannabidiol did not attenuate the effect of standard treatment of triple-negative breast cancer and human epidermal growth factor receptor 2 positive breast cancer cell lines with trastuzumab and cisplatin.
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These authors contributed equally to this work and share first authorship.
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