Antidepressant Use and Breast Cancer

Depression is common among breast cancer patients. The shock of a diagnosis, the side effects of treatment, and the stress of an unknown outcome can lead to depression or anxiety. Research has shown that almost half of the 2.4 million breast cancer survivors in the United States take antidepressants to manage their mental health.

Though these drugs can help people manage the mental health aspects of having breast cancer, they can also pose a threat. Studies have shown the possible negative interactions between certain antidepressants and tamoxifen, a drug that treats all stages of breast cancer. The drug is also used to reduce the onset of breast cancer in people at high risk for the disease.

This article describes the effects of certain antidepressants on breast cancer drugs. It covers the options for antidepressants, the benefits for breast cancer patients, and how to safely take breast cancer drugs and antidepressants.

Antidepressants: A Breast Cancer Risk Factor?

Animal studies have suggested that both selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs) could increase the overall risk of breast cancer and promote tumor growth. However, a meta-analysis of the connection between antidepressant use and the risk of breast cancer in humans did not identify an increase in breast cancer diagnoses among people who used either type of antidepressant.

The link between antidepressants and breast cancer in humans has been seen in people who take tamoxifen. Tamoxifen works by blocking estrogen from connecting to cancer cells and promoting their growth in hormone receptor-positive breast cancers. These cancers need estrogen and/or progesterone to grow.

Since tamoxifen also works like estrogen in other tissues (such as the bones and uterus), it is called a selective estrogen receptor modulator (SERM) and is a type of hormone therapy. The effects of the drug may last up to 20 years after you stop taking it.

To be effective, tamoxifen must be metabolized by the liver enzyme CYP2D6. Some antidepressants can interfere with this process and reduce the effectiveness of the drug when it's used as cancer therapy or as a preventive measure.

Taking Breast Cancer Medication and Antidepressants

In a large population-based study that included almost 17,000 people with breast cancer, 30.6% reported taking at least one antidepressant while they were taking tamoxifen.

Selective serotonin reuptake inhibitors (SSRIs) are a class of drugs that are considered the first-line pharmacotherapy for depression. They are the most commonly prescribed antidepressants because of their safety, tolerability, and efficacy.

However, some SSRIs and other antidepressants can interfere with the action of the CPY2D6 enzyme that is required to activate tamoxifen.

While you can safely take tamoxifen and some antidepressants together, there are certain ones that you should avoid. The following antidepressants are known to be strong inhibitors of the CPY2D6 enzyme and may interfere with the effectiveness of tamoxifen:

• Prozac (fluoxetine)
• Paxil (paroxetine)
• Wellbutrin (bupropion)
  

You should also avoid antidepressants that are known to be moderate inhibitors of the CYP2D6 enzyme, including:

• Cymbalta (duloxetine)
• Celexa (citalopram)
• Lexapro (escitalopram)
  
• Sinequan (doxepin)

Benefits for People With Breast Cancer

Protecting the benefits of tamoxifen is key for people with breast cancer. The drug has been used for 40 years with success for the following purposes:

• To reduce the risk of breast cancer before it develops for people who have a higher-than-average risk of the disease
• To treat people diagnosed with advanced-stage, hormone receptor-positive breast cancer
• To help extend longevity and prevent the risk of recurrence for people who have not yet gone through menopause and who have had surgery for hormone receptor-positive, early-stage breast cancer
• To reduce the risk of invasive breast cancer in people diagnosed with hormone receptor-positive DCIS (ductal carcinoma in situ) after surgery

While tamoxifen is key for treating the physical aspects of breast cancer, antidepressants have an important role in managing the mental health aspects of going through treatment.

Antidepressants can also be effective as a non-hormonal option for treating certain menopausal-like symptoms that can occur with tamoxifen treatment. These symptoms can happen due to the drug's estrogen-blocking properties, which cause low estrogen. The most common side effects of tamoxifen include:

• Hot flashes
• Vaginal dryness or discharge
• Disruption of the normal menstrual cycle

Over 25% of people who experience hot flashes while being treated with tamoxifen use antidepressants to control their symptoms so they can continue using the anti-cancer medication.

However, not all antidepressants are as effective at treating these symptoms.

For example, the drug Wellbutrin (bupropion) may not be best for treating hot flashes. According to a double-blind randomized study, the drug did not show a statistically significant reduction in the number of hot flashes between the breast cancer survivors who took it and the people who took a placebo.

Antidepressant Alternatives

While certain antidepressants cannot be combined with tamoxifen treatment, there are many other options for treating depression and anxiety. Your healthcare provider can determine which drugs will be most effective and least risky.

You might be able to use certain antidepressants that are considered weak inhibitors of the CPY2D6 enzyme. These drugs are not restricted by treatment with tamoxifen:

• Effexor XR (venlafaxine)
• Pristiq (desvenlafaxine)
• Trintellix (vortioxetine)
• Viibryd (vilazodone)
• Fetzima (levomilnacipran)

Depending on your depression symptoms, you may want to talk to your provider about natural depression remedies as an alternative to drug therapy.

Natural alternatives to antidepressants can include:

• St. John's wort: Also known as Hypericum perfornatum, St. John's wort is an herb derived from a flowering plant. St. John's wart should not be taken with tamoxifen.
• Omega-3 fatty acids: These essential fatty acids must be consumed through your diet because your body cannot produce them naturally. They are commonly found in foods like fish and nuts and can be consumed through fish oil supplements.
• SAMe: Also known as S-adenosylmethionine or ademetionine, SAMe is the synthetic form of a compound that is made naturally in the body from methionine (an essential amino acid) and adenosine triphosphate (an energy-producing compound).
• Folic acid: This is a synthetic form of folate, the natural form of vitamin B9. Since your body does not store folate, you must replenish your supply by eating foods that are rich sources of folate like dark green vegetables, beans, and legumes. You can also take folic acid supplements.
• 5-Hydroxytryptophan: Also called 5-HTP, this is an amino acid that your body makes naturally. Consuming 5-HTP through supplements is more effective than trying to consume the substance through dietary sources.
• Nutritious diet: A balanced diet that includes less sugar, limited alcohol, and recommended amounts of vitamin B6 and magnesium may help reduce the severity of mood swings and depression. Consuming plenty of fruits, vegetables, and fiber is also linked to a reduced risk of depression.
• Exercise: You might be able to lower your risk of depression through exercise. The results of one study showed that people might be able to achieve these benefits with relatively small doses of movement, starting with activities equivalent to 1.25 hours of brisk walking per week.
• Light therapy: Getting enough sunlight can help offset depression, especially if you are also sensitive to mood changes that occur during the winter when the days are shorter. If you can't get exposure to natural sunlight during the day, consider trying light box therapy, which can provide the benefits of light indoors.
  
  

Summary

The risk of depression is over five times higher in people with cancer than in people without the disease. Dealing with the shock of having breast cancer, the side effects of treatment, and the stress of an unknown outcome can lead to mental health conditions like depression. Almost 50% of people with breast cancer use antidepressants to help cope with their symptoms.

While these drugs can help you manage the mental health aspects of having breast cancer, they may also inhibit the effects of certain cancer-fighting drugs. Some antidepressants can prevent you from getting the full benefits of the drugs you are taking for breast cancer treatment.

If you have breast cancer, talk to your provider about the best treatment options for you to manage your cancer and mental health diagnoses.

A Word From Verywell

Breast cancer can be a devastating diagnosis. It's normal to feel nervous and worried about having treatment and your future at any stage of the process. However, if you notice that you're frequently feeling sad, uninterested in your normal activities, and unable to sleep, these can be symptoms of depression.

It's important to discuss your feelings with your healthcare provider if you feel overwhelmed by these emotions. Protecting your mental health is an important aspect of helping your body stay strong during all stages of cancer treatment—especially if you're taking a long-term drug like tamoxifen, which can require five to 10 years of treatment.

Depression and breast cancer are two serious diagnoses on their own, but getting the right combination of treatments can help you achieve the best outcomes with both.