Recent research has uncovered an intriguing link between certain hormones and neurotransmitters and breast cancer treatment. This connection involves four key players: estrogen, serotonin, dopamine and progesterone. Each of these substances plays a crucial role in various bodily functions, but their impact on cancer growth and treatment is now coming into sharper focus.
Estrogen, primarily known as a female sex hormone, regulates reproductive processes, bone density and cardiovascular health. However, it’s also recognized for its ability to promote cancer growth. Many breast cancers, for instance, are classified as estrogen-receptor positive, meaning they grow in response to estrogen.
Serotonin, often misleadingly called the “feel-good” neurotransmitter, is an antimetabolite, meaning it suppresses your body’s ability to create energy in the electron transport chain of your mitochondria. Recent studies suggest serotonin also stimulates the growth and spread of cancer cells.1
On the other hand, dopamine, another neurotransmitter, is showing promise in cancer treatment. Typically associated with pleasure, motivation and reward systems in your brain, dopamine is being investigated for its anticancer properties. Research indicates that it may help inhibit tumor growth and enhance the effectiveness of certain cancer treatments.2
Progesterone, another sex hormone crucial for reproductive health and pregnancy, is also emerging as an ally in cancer treatment, because it’s not only anti-estrogen but also inhibits cortisol and improves mitochondrial production of cellular energy by blocking estrogen and cortisol.
Dopamine’s Cancer-Fighting Potential
A study published in Applied Sciences examined how drugs that affect dopamine and serotonin receptors could improve the effectiveness of standard chemotherapy drugs like paclitaxel when used together.3
The researchers tested several repurposed drugs that act on dopamine and serotonin pathways, looking for those that could reduce breast cancer cell viability. Two drugs showed particular promise — benztropine and thioridazine.
Benztropine is typically used to treat Parkinson’s disease, while thioridazine is an antipsychotic medication. When combined with paclitaxel, both of these dopamine-targeting drugs demonstrated a synergistic effect, meaning they enhanced paclitaxel’s ability to kill breast cancer cells beyond what either drug could do alone.
The study found benztropine and thioridazine were able to reduce breast cancer cell viability on their own, even without paclitaxel. This suggests these dopamine-modulating drugs have inherent anticancer properties.
Importantly, benztropine and thioridazine target different pathways than standard chemotherapy drugs. They may help overcome chemotherapy resistance and attack cancer through multiple mechanisms. Some research indicates they even target elusive cancer stem cells that often evade conventional treatments.
While dopamine shows promise for fighting cancer, the study results suggest serotonin may play a more harmful role.4 Drugs that increase serotonin activity or block its reuptake did not demonstrate anticancer effects in this research. In fact, some evidence indicates serotonin may stimulate cancer cell growth and proliferation.5 As bioenergetic researcher Georgi Dinkov explains:6
“I discovered a multitude of studies demonstrating serotonin (5-HT) is both a cause and promoter of cancer, and that dopamine activates the progesterone receptors … with the final conclusion being that estrogen/serotonin cause and promote cancer, while progesterone/dopamine are therapeutic.”
Understanding Dopamine’s Anticancer Mechanisms
The study’s findings provide compelling evidence for dopamine’s cancer-fighting abilities. While the exact mechanisms are still being investigated, several factors contribute to dopamine’s potential as an anticancer agent:7
1. Direct tumor suppression — The study showed that dopamine-modulating drugs like benztropine and thioridazine could reduce breast cancer cell viability on their own. This suggests that increasing dopamine activity may directly inhibit tumor growth.
2. Targeting multiple pathways — Dopamine-modulating drugs affect cancer cells through different mechanisms than conventional chemotherapy. This multi-pronged approach could help overcome drug resistance, a common problem in cancer treatment.
3. Affecting cancer stem cells — Some research indicates that dopamine-targeting drugs may be effective against cancer stem cells, which are often resistant to conventional treatments and lead to cancer recurrence.
4. Counteracting serotonin’s effects — Given that serotonin may promote cancer growth, dopamine’s anticancer properties could be partly due to its ability to balance or counteract serotonin’s effects in your body.
These findings suggest that dopamine plays a more complex role in cancer biology than previously thought. By leveraging dopamine’s cancer-fighting abilities, researchers may be able to develop more effective and less toxic cancer treatments in the future. However, more research, including animal studies and human clinical trials, is needed to fully understand and harness dopamine’s anticancer potential.
Expanding on Dopamine’s Role in Fighting Cancer
While the previous study discussed benztropine and thioridazine, another drug has also shown promising results in this field. Selegiline, also known as L-deprenyl, is an antidepressant that belongs to a class of drugs called monoamine oxidase (MAO) inhibitors.8
A study conducted by Indian researchers found that selegiline might be effective as an anticancer therapeutic for breast cancer.9 What’s particularly exciting about this finding is that selegiline was effective against various types of breast cancer cells, including the notoriously difficult-to-treat triple-negative breast cancer (TNBC).
Selegiline works by inhibiting monoamine oxidase B (MAO-B), which increases dopamine levels in the brain. Selegiline induces cell death in cancer cells through pathways that don’t rely on reactive oxygen species (ROS). This is significant because many conventional cancer treatments focus on increasing ROS to kill cancer cells, but this approach also damages healthy cells.
While selegiline is a prescription drug, there are natural compounds that may have similar effects. Naphthoquinones, such as vitamin K, and eugenol, the main constituent of clove oil, have been shown to be potent and selective MAO-B inhibitors.10
These findings, along with the earlier research on benztropine and thioridazine, paint a compelling picture of dopamine’s role in cancer biology. They suggest that maintaining healthy dopamine function in your body could be a valuable part of a holistic cancer prevention strategy.
The research on dopamine’s role in cancer treatment opens up exciting possibilities not just for breast cancer but for other types of cancer as well. The fact that dopamine-modulating drugs have shown effectiveness against different breast cancer subtypes suggests that this approach might be applicable to a wide range of cancers.
Furthermore, this research underscores the complex interplay between neurotransmitters and cancer biology. It highlights the need for a more holistic approach to cancer treatment and prevention, one that considers not just the cancer cells themselves, but also the broader physiological context in which they develop and grow. Dinkov adds:11
“… All in all, the evidence continues to accumulate that pro-metabolic, anti-estrogenic, anti-serotonin, progestogenic and dopaminergic pathways are highly beneficial not only for a large number of very serious degenerative conditions, but they make one slim, happy, frisky (due to the antiprolactin effects) and long-living.
And since estrogenic (PUFA, birth control, endocrine disruptors, etc.) and serotonergic (SSRI) substances functionally approximately opposite to selegiline, you can imagine what their effects are.”
Natural Dopamine in Cancer Prevention
While the Applied Sciences study focused on pharmaceutical drugs that modulate dopamine, it raises intriguing questions about the role of your body’s natural dopamine in cancer prevention and treatment. Could boosting your dopamine levels naturally help lower your cancer risk?
The study’s findings suggest that increased dopamine activity may indeed have anticancer effects. Your body produces dopamine naturally, and there are several ways to increase your dopamine levels without medication:
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Exercise — Regular physical activity has been shown to boost dopamine production and release in your brain. |
Sleep — Getting adequate, quality sleep helps regulate your body’s dopamine systems. |
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Diet — Consuming foods rich in tyrosine, a precursor to dopamine, may help. These include bananas, beef, eggs and green tea. |
Sunlight exposure — Sunlight not only helps your body produce vitamin D but may also increase dopamine levels. |
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Music — Listening to music you enjoy has been linked to increased dopamine release in your brain. |
Meditation and stress reduction — Chronic stress depletes dopamine, while meditation and other stress-reduction techniques may help maintain healthy levels. |
Estrogen Is a Known Human Carcinogen
Estrogen’s carcinogenic properties are well-established. The Women’s Health Initiative (WHI) studies, which began in 1991,12 showed estrogen replacement therapy in menopausal women significantly increased the risk of breast cancer and cancer of all female reproductive organs, as well as raising the risk of heart attacks, strokes, dementia and Parkinson’s disease.
The publication of the WHI results led to a significant decline in estrogen replacement therapy, starting in the late 1990s, early 2000s, until about 2015, when studies refuting those earlier results started coming out. Scientists argued estrogen could be safely used if dosed and timed better. Cancer rates don’t bear that out though.
The biochemical role of estrogen is to support wound healing. In cases of tissue trauma, estrogen reverts the differentiated cells in that specific tissue back to a stem cell-like condition, to repair the damaged tissue. In young, healthy women, progesterone turns off estrogen’s activity. Progesterone declines with age, but estrogen synthesis typically does not. Hence, if your estrogen is high and progesterone low, your cancer risk will rise.
Progesterone is the antidote because it is not only anti-estrogen but also inhibits cortisol and will improve mitochondria production of cellular energy by blocking estrogen and cortisol. Detailed information on how to use progesterone is below, but additional commonsense strategies to help you limit your estrogen exposure and lower your estrogen load include:
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Avoid synthetic estrogens — Minimize exposure to synthetic estrogens, such as those found in hormone replacement therapy and oral contraceptives. Consult with a qualified health care professional about alternative treatments and/or contraceptive methods with lower estrogen content. |
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Avoid endocrine-disrupting chemicals (EDCs) — Exposure to EDCs from sources like microplastics is over activating your estrogen receptors. To reduce your exposure, filter your drinking water, swap plastic bags, bottles, straws, utensils and food containers for non-plastic options and choose food with minimal natural packaging or glass packaging instead of plastic. |
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Avoid linoleic acid (LA) — Omega-6 polyunsaturated fats (PUFAs) like LA functions very similarly to estrogen as they both increase your risk for cancer and decrease metabolic function. Read my comprehensive LA article for more details. |
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Choose natural products — Opt for natural and organic personal care products, including makeup, skin care and hair care items, to reduce exposure to synthetic chemicals like parabens and phthalates, which have estrogenic properties. |
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Limit pesticide exposure — Choose organic produce whenever possible to reduce exposure to pesticides, many of which have estrogenic effects. Washing fruits and vegetables thoroughly helps remove pesticide residues. |
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Rethink your household products — Many household cleaning products, laundry detergents and air fresheners contain chemicals with estrogenic properties. Swap them out for natural, nontoxic alternatives or make your own cleaning solutions using vinegar, baking soda and essential oils instead. |
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Avoid plastic containers — Minimize the use of plastic containers and food packaging, which leach estrogenic compounds into food and beverages. Instead, opt for glass or stainless steel containers for food storage and water bottles. |
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Maintain a healthy weight — Aim for a healthy weight and body composition through a balanced diet and regular exercise. Excess body fat, particularly around your thighs, hips and buttocks, contributes to higher estrogen levels. |
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Support liver health — Support liver function, as your liver plays a crucial role in metabolizing and eliminating excess estrogen from your body. Eat a nutrient-rich diet, avoid alcohol consumption and consider incorporating liver-supporting herbs and supplements, such as milk thistle or dandelion root. |
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Promote hormonal balance — Explore natural approaches to promote hormonal balance, such as consuming cruciferous vegetables (such as broccoli, cauliflower and kale), which contain compounds that help support estrogen metabolism and detoxification. |
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Reduce stress — Manage stress through relaxation techniques like meditation, deep breathing exercises, yoga or spending time in nature. Chronic stress disrupts hormone balance, including estrogen levels, so prioritizing stress reduction is essential. |