Caffeine and Breast Cancer

There may be a connection between caffeine consumption and breast cancer, but experimental results are not consistent, and factors such as brewing methods and other preparation techniques contribute to the mixed research outcomes.

This article will discuss the relationship between caffeine and breast cancer.

woman holding cup of coffee
 Willie B. Thomas / Getty Images

Caffeine and Breast Cancer Risk

Caffeine consumption has been associated with a decreased risk of breast cancer in a few studies, though the results have been inconsistent. Furthermore, more research is needed into the reason for the possible link, as well as the timing and amount of caffeine that could potentially have any effect on breast cancer.

One group of researchers in Italy examined 21 studies on this subject but were unable to find a clear relationship between caffeine consumption and the risk of breast cancer. However, drinking four cups of coffee per day was associated with a 10% reduction for postmenopausal women.

A Swedish study found that coffee consumption was associated with a slightly decreased breast cancer risk, and tea consumption was associated with an increased risk of breast cancer.

Researchers who conducted a large multinational trial also suggested that a higher intake of caffeinated coffee is associated with a lower risk of breast cancer in postmenopausal women, while decaffeinated coffee was not associated with any impact.

Contradictory Results

Although the research is interesting, the relationship between caffeine and breast cancer is complicated and unclear. Conflicting conclusions only support how much more there is to know about this topic.

The Swedish study that showed a reduction in breast cancer in postmenopausal women who consumed coffee also found that caffeinated tea consumption was associated with an increase in breast cancer, though the reason for this is unclear.

And, the multinational trial, which also looked at tea and coffee consumption, did not prove any relationship between tea (or decaffeinated coffee) and premenopausal or postmenopausal breast cancer.

While research is ongoing, it's important to remember that many foods and beverages have components that may, together or alone, have an influence on cancer risk.

Furthermore, a different multicenter trial (involving more than one research institution) showed that the potentially beneficial effect of coffee on breast cancer must be weighed carefully when it comes to postmenopausal women using hormone therapy.

According to the trial:

  • Researchers found that postmenopausal women who consumed more than four cups of coffee per day had a 16% reduced risk of breast cancer compared to women who consumed less than seven cups of coffee per week.
  • However, women who used postmenopausal hormone therapy and consumed more than four cups of coffee per day had a 22% greater risk of breast cancer than women consuming less than seven cups per week.

Preparation Methods of Coffee and Tea

The method by which caffeinated beverages are prepared adds another variable. A 2019 study on Chinese women in Hong Kong found that consuming coffee products did not increase the risk of breast cancer.

When broken down by preparation methods, however, there were significant differences. Women who drank brewed coffee, for instance, were, on average, 52% less likely to develop breast cancer. In contrast, those who drank instant coffee were 50% more likely to develop the disease.

Preparation techniques used for green tea and coffee can affect phytonutrients, as well as carcinogens (cancer-causing agents).

Combining Caffeine With Traditional Therapy

There are many factors at play when it comes to the relationship between coffee and breast cancer, and its effects when combined with cancer treatment have begun to be examined.

Caffeine has antioxidant and anti-inflammatory functions. Antioxidants counteract oxidation—a chemical process that leads to cancer and heart disease. Inflammation worsens many different diseases, including cancer.

  • A 2020 study showed that caffeine combined with the chemotherapy drug cisplatin in a laboratory setting increased the effect of cisplatin on triple-negative breast cancer cells. Triple-negative breast cancer is highly aggressive due to the absence of hormone receptors.
  • Another study noted that women who consumed high amounts of caffeine and were treated with tamoxifen for breast cancer prevention were less likely to develop the condition. The researchers also evaluated the response of cancer cells to the caffeine in a laboratory setting and found that cell growth was suppressed in estrogen receptor-positive (ER+) and estrogen receptor-negative (ER-) samples. The researchers theorized that caffeine can make women more sensitive to the beneficial effects of the drug.

Because findings in laboratory experiments are not always the same when they are applied to humans, the effects of caffeine on breast cancer cells would have to be replicated in humans in a clinical trial before it would be accepted as a treatment for breast cancer.

Can Caffeine Affect Breast Cancer Outcomes?

A 2021 study suggests that coffee may improve breast cancer survival, according to the American Institute for Cancer Research. People drinking more than three cups of coffee a day had a 25% lower risk of dying from breast cancer compared with those who abstained from coffee.

People drinking three cups of tea daily after a breast cancer diagnosis had a 26% lower risk of dying from any cause compared with people who did not drink tea.

Other factors that impacted survival included breast cancer treatment, body mass index (BMI), and physical activity.

Green Tea and Breast Cancer Recurrence

Many people who have had breast cancer worry about the risk of recurrence. While there is no solid evidence of coffee intake and breast cancer recurrence risk, the caffeinated beverage green tea might be an option to consider.

Green tea consumption has been demonstrated to have anti-cancer properties, and it appears to reduce the risk of late recurrence of breast cancer (cancer that returns after five years).

The right amount or maximum amount of caffeine differs for everyone, but it can range from one to five servings of a caffeinated beverage or food per day.

A Word From Verywell

For the casual coffee drinker, having a cup can be a nice way to start your day and help you focus. It also may help with headaches, even migraines. However, people with certain health conditions like high blood pressure may want to ease up on the caffeine.

Beyond its potential influence on cancer risk, caffeine may affect breast pain. For instance, some women with fibrocystic breast tissue notice that when they avoid caffeinated products, their breast symptoms improve. This could be related to caffeine's tendency to heighten symptom awareness, which can increase pain sensitivity.

Caffeine may have an impact on breast cancer, but it's important to keep in mind that hormone therapy and other risk factors play a far stronger role in breast cancer risk than coffee or tea do.

Frequently Asked Questions

  • Can caffeine affect breast health?

    Though more studies are needed, some research has linked caffeine consumption with a decreased risk of breast cancer in some women. However, women with fibrocystic breast tissue may experience less pain and discomfort when they avoid caffeine.

  • Should people with breast cancer drink coffee and tea?

    There is no need to start drinking coffee or tea if you don't already enjoy these beverages. According to the American Institute for Cancer Research, a 2021 study suggested that drinking more than three cups of coffee a day was associated with a 25% lower risk of dying from breast cancer compared with people who abstained from coffee. Also, women drinking three cups of tea daily after a breast cancer diagnosis have a 26% lower risk of dying from any cause compared with people who did not drink tea.

    However, there are many other variables that have a stronger influence on breast cancer than caffeine does—these include getting cancer treatment, not smoking, eating healthy, staying hydrated, and getting enough exercise.

  • Can caffeine cause breast cysts?

    No, caffeine does not cause breast cysts. However, some women with fibrocystic breast tissue notice that when they avoid caffeinated products, their breast symptoms improve. Caffeine has a tendency to heighten symptom awareness, which can increase pain sensitivity.

  • Does caffeine affect your hormones?

    Yes, caffeine consumption is linked to estrogen changes. Hormone therapy and other risk factors play a far stronger role on the risk of breast cancer than coffee does, however.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  5. Lee PMY, Chan WC, Kwok CC, et al. Associations between Coffee Products and Breast Cancer Risk: a Case-Control study in Hong Kong Chinese Women. Science Reports. 2019. 9(1):12684. doi:10.1038/s41598-019-49205-x

  6. Pascua SM, McGahey GE, Ma N, Wang JJ, Digman MA. Caffeine and Cisplatin Effectively Targets the Metabolism of a Triple-Negative Breast Cancer Cell Line Assessed via Phasor-FLIM. Int J Mol Sci. 2020 Apr 1;21(7):2443. doi: 10.3390/ijms21072443. PMID: 32244616; PMCID: PMC7177700.

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  8. American Institute for Cancer Research. Study suggests coffee may improve survival after breast cancer.

Originally written by Pam Stephan
Pam Stephan is a breast cancer survivor.
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