Study: Drinking coffee or tea may improve survival after breast cancer

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Contents

At a glance Clinical trials
Study findings Guidelines
Strengths and limitations Questions for your doctor
What does this mean for me? Resources
In-depth  

 

STUDY AT A GLANCE

What is this study about?

This study looks at how drinking coffee or tea affects the survival of people who are diagnosed with stage 1, 2 or 3 breast cancer.

 

Why is this study important?

Many people regularly drink coffee and tea. This study finds that these beverages are not harmful and may be linked to a lower risk of death after a breast cancer diagnosis. For breast cancer survivors who are concerned with how diet affects their chance of cancer returning, this study adds some clarity to one part of daily life.

 

Study findings

This study looked at coffee and tea intake among 8,900 participants with stage 1, 2 or 3 breast cancer. Participants self-reported their breast cancer diagnosis, which was then confirmed by medical records and pathology reports. Every four years for up to 30 years, participants were asked to complete a food frequency questionnaire (FFQ) describing what they ate and drank. The average follow-up time was 11.5 years. Death reports were confirmed by death certificates and medical record reviews by physicians for the cause of death.

During the study, 1,054 participants died of breast cancer and 2,501 died of any cause (including breast cancer). Participants drank 1.7 cups of coffee and 0.7 cups of tea daily on average after their breast cancer diagnosis.

 

Drinking coffee lowers the risk of dying from breast cancer

Participants who drank coffee after their breast cancer diagnosis survived longer than participants who did not drink coffee. The more coffee they drank, the more their chance of breast cancer survival improved. Participants who drank coffee also had fewer deaths from any cause.
 

Drinking tea and the risk of dying from breast cancer

Participants who drank more tea had a lower risk of dying from any cause than those who did not drink tea. (Their breast cancer survival was not improved or worsened.)

 

Coffee drinking before breast cancer diagnosis was not linked to breast cancer survival

Coffee and tea consumption before a breast cancer diagnosis was not linked to breast cancer-specific death. In other words, how much coffee a person drank before diagnosis did not affect their breast cancer survival.  One exception was an increased risk among participants who drank more coffee before being diagnosed but drank less coffee after they were diagnosed.

 

Decreasing coffee consumption after breast cancer diagnosis increased risk

Participants who lowered their coffee intake from more than two cups per day before breast cancer diagnosis to no coffee after diagnosis had a 91 percent higher risk of breast cancer-related death than participants who did not drink coffee before or after a breast cancer diagnosis.

Participants who lowered their coffee intake from more than two cups per day before breast cancer diagnosis and then drank less (up to 2 cups of coffee each day) after diagnosis had a 34 percent higher risk of breast cancer-related death than participants who did not drink coffee before or after a breast cancer diagnosis.

 

Other factors may influence the risk of breast cancer death among coffee drinkers

Researchers mentioned several factors with impacts on survival that could not be separated from coffee or tea intake. Participants with higher coffee consumption after diagnosis were also:

  • more likely to drink more alcohol, smoke, consume more animal fat and use aspirin more frequently after diagnosis.
  • less likely to have radiotherapy or chemotherapy.

Researchers tried to account for the potential effect of other factors in their analysis. However, the findings regarding coffee or tea consumption may be due in part to these confounding factors.

Researchers noted that several factors did not contribute to the effects observed, including:

  • age
  • body mass index (BMI) after breast cancer diagnosis
  • stage of cancer
  • amount of coffee or tea consumed on average before breast cancer diagnosis

 

Strengths and Limitations

Overall, this is a well-designed and appropriately analyzed study. The researchers were careful to point out weaknesses as well as highlight major findings.

Strengths

  • A major strength of this study is that 8,900 participants were enrolled. Larger studies are typically more accurate because there is a greater chance of detecting differences when they occur.
  • Another strength is the regular follow-up on participants’ health rather than relying on memory recall of health and diet history.
  • The follow-up period was long (11.5 years on average), allowing a comprehensive understanding of participants’ coffee and tea consumption.
  • Self-reports of health and breast cancer diagnosis were validated with a review of medical records and where needed, testing tumor tissue to verify cancer type.

 

Limitations

  • Confounding factors are the biggest limitations of this study. Several factors (smoking, alcohol consumption and less use of chemotherapy and radiation therapy) vary in the same way that coffee and tea consumption do. For example, people who drank more coffee usually smoked more and drank more alcohol. While the researchers used statistical tools to ask whether these factors rather than coffee were responsible for the findings, a concern remains that the decrease in risk of breast cancer deaths may be from a combination of these factors in addition to coffee or tea consumption.
  • The study population was not diverse. Most participants were well-educated, non-Hispanic white women. These findings may not be generalizable to the more diverse U.S. population.
     

What does this mean for me?

If you are a breast cancer survivor, this study suggests that drinking coffee will not increase your chance of dying of breast cancer and may improve your chance of breast cancer-related survival. Individuals who drank more than three cups of coffee daily had the best survival. However, decreasing your coffee consumption after diagnosis to less than what it was before diagnosis may decrease your chance of breast cancer-related survival. Drinking tea may increase your overall survival, but this study found that it has little effect on breast cancer-specific survival.

Ask your healthcare provider whether drinking coffee or tea is okay for your situation and health history. Some people need to avoid caffeine from coffee, tea or other sources for other medical reasons.

This XRAY was reviewed by FORCE's Scientific Advisory Board.

 

Share your thoughts on this XRAY review by taking our brief survey.  

posted 8/31/21


Reference

Farvid MS, Spence ND, Rosner BA, et al. Post-diagnostic coffee and tea consumption and breast cancer survival. British Journal of Cancer. 2021. 124:1873-1881.

 

This article is relevant for:

Women with breast cancer who drink coffee or tea.

This article is also relevant for:

People with breast cancer

People with triple negative breast cancer

Men with breast cancer

People with Her2-positive cancer

People with ER/PR + cancer

People newly diagnosed with cancer

Be part of XRAY:

Expert Guidelines

The National Comprehensive Cancer Network (NCCN) guidelines on survivorship recommend the following: 

  • Assess dietary intake of fruits, vegetables and unrefined grains, as well as red and processed meats, alcohol, and processed foods or beverages with added fats and/or sugars. 
  • Assess eating habits, including portion size, night grazing, snacking habits, frequency of eating out and use of added fats or sugars to foods or beverages
  • All survivors should be encouraged to:
    • Make informed choices about food to ensure variety and adequate nutrient intake
    • Limit refined sugars
    • Eat a diet that is at least 50% plant-based, with the majority of food being vegetables, fruit and whole grains
    • Track calorie intake
      • Self-monitoring of caloric intake is an effective strategy for weight management
    • Minimize alcohol intake
      • Limit intake to no more than one drink per day for a woman and two drinks per day for a man
  • For patients desiring further recommendations for dietary guidelines, the USDA approximate food plate volumes are:
    • Vegetables and fruits should comprise half the volume of food on the plate
    • Vegetables: 30% of plate; Fruits 20% of plate
    • Whole grains: 30% of plate
    • Protein: 20% of plate
  • Recommended sources of dietary components:
    • Fat: plant sources such as olive or canola oil, avocados, seeds and nuts, and fatty fish
    • Carbohydrates: fruits, vegetables, whole grains and legumes
    • Protein: poultry, fish, legumes, low-fat dairy foods, and nuts

Other experts, including the following, also provide guidelines for nutrition and health: 

Updated: 11/20/2021

Questions to Ask Your Doctor

  • What lifestyle factors most affect my chance of cancer recurrence?
  • Do you recommend that I change my diet?
  • Do you recommend that I change my coffee or tea consumption?
  • Would I benefit from talking to a nutritionist?

Open Clinical Trials

The following are studies focused on nutrition for people diagnosed with breast cancer. 

Visit our Featured Research Page and Research Search and Enroll Tool to find additional studies enrolling people with, or at high risk for cancer.

Updated: 11/21/2021

Find Experts

You can find a registered dietician in your area using the search tool from the Academy of Nutrition and Dietetics.  

Updated: 11/13/2021

Who covered this study?

Real Health

Coffee May Improve Survival After Breast Cancer This article rates 4.0 out of 5 stars

How we rated the media

IN-DEPTH REVIEW OF RESEARCH

 

Study background

Coffee and tea are some of the most commonly consumed beverages worldwide. Both contain many active ingredients, including caffeine, which is the most well-known active ingredient. Coffee, tea and caffeine have been linked to improved insulin sensitivity, reduced inflammation and antioxidant activity. Each of these factors has been suggested to improve cancer prevention.

Coffee has been implicated in protection against liver and endometrial cancer, however, the effect of coffee or tea on breast cancer has not been clear. Previous findings regarding these beverages and breast cancer outcomes have been contradictory. In several studies, drinking coffee before a diagnosis of breast cancer was not linked to more or less cancer-specific deaths or deaths from any cause. On the other hand, in the Cancer Prevention Study II, the level of coffee consumption before a breast cancer diagnosis was linked to lower breast cancer death in nonsmokers.

In studies of coffee consumption after a breast cancer diagnosis, one small, 96-person study saw an increased risk of breast cancer death, while another larger 576-person study saw a decrease in breast cancer mortality but only among those who were treated with tamoxifen for estrogen receptor-positive cancer.

In this study, researchers look at the association between coffee and tea consumption and breast cancer in two large groups of women: participants in the Nurses' Health Study and the Nurses' Health Study II. Participants in these studies reported beverage consumption along with many other dietary and health factors both before and after their breast cancer diagnoses.

 

Researchers of this study wanted to know

Researchers wanted to know whether coffee or tea consumption affects the chance of death due to breast cancer or to any other cause. 

 

Populations looked at in this study

This study looked at information from 8,900 participants with breast cancer (stages 1 to 3) from the Nurses’ Health Study (NHS) and the Nurses’ Health Study II (NHSII). Participants were excluded if their diet information was missing at the time of the survey 12 months after diagnosis, their total energy intake was unusually low or high (below 600 or above 3,500 kcal/day), more than 70 food items or all coffee and tea questions were left blank on the food frequency questionnaire (FFQ), they had been diagnosed with any cancer other than non-melanoma skin cancer prior to their breast cancer diagnosis or they were diagnosed initially diagnosed with stage 4 cancer.

 

Study design

Researchers looked at coffee and tea consumption using a validated food frequency questionnaire (FFQ) given before participation and every four years after breast cancer diagnosis for up to 30 years (the average follow-up time was 11.5 years). Coffee or tea consumption was separated into regular or decaffeinated groups and then broken down by the average amount consumed per day: more than three cups, two to three cups, 0 to two cups or none.

Participants self-reported breast cancer diagnoses on health questionnaires every two years. Cancer diagnosis and type, stage and treatment were confirmed by medical records and pathology reports. In some cases, tissue samples were used to determine the presence or absence of tumor biomarkers. Death reports were confirmed by death certificates and medical record reviews by physicians to determine the cause of death. Participants were followed after returning their first FFQ before a breast cancer diagnosis through the end of the study (June 1, 2014, for NHS and June 2, 2015, for NHSII) or death.

 

Study findings

Exactly 8,900 women participated in this study. During the follow-up time (an average of 11.5 years), 1,054 participants died of breast cancer and 2,501 died of any cause (including breast cancer). Participants drank 1.7 cups of coffee and 0.7 cups of tea on average after their breast cancer diagnosis.

 

Drinking more coffee is linked to a lower chance of dying of breast cancer

Participants who drank greater amounts of coffee after a breast cancer diagnosis had a lower risk of dying of breast cancer less often than participants who did not drink coffee.

  • Those who drank more than three cups of coffee each day had a 25% lower risk of dying of breast cancer than those who drank no coffee.
  • For each daily cup of caffeinated coffee, the risk of breast cancer death was 7% lower; each cup of decaffeinated coffee reduced risk by 2%.

Participants who drank more coffee had a lower risk of dying from any cause than those who did not drink coffee.

  • Those who drank more than 2 to 3 cups of coffee daily had a 24% lower risk of dying of any cause than those who drank no coffee.
  • Those who drank more than 3 cups of coffee daily had a 26% lower risk of dying of any cause than those who drank no coffee.
  • For each cup of caffeinated coffee per day, the risk of death from any cause was 7% lower; the risk was 5% lower for each cup of decaffeinated coffee.
     

Drinking tea and risk of dying of breast cancer

Participants who drank more tea had a lower risk of dying from any cause, but not specifically of breast cancer than those who did not drink tea.

  • Those who drank more than 3 cups of tea each day had a 26% lower risk of dying of any cause than those who drank no tea.
  • Women with drank more tea were also more likely to have chemotherapy or hormonal treatment.

 

Overall caffeine consumption and breast cancer death

When researchers looked at caffeine intake from all sources, greater caffeine intake was linked to fewer breast cancer-specific deaths and fewer deaths from any cause. Overall, caffeine consumed after breast cancer diagnosis seemed to be protective.

 

Type of cancer and coffee or tea consumption

To look at cancer types, researchers grouped consumption of caffeinated and decaffeinated coffee and grouped consumption of caffeinated and decaffeinated tea. They considered whether the risk of breast cancer death was different between groups that consumed more versus less coffee or tea in different types of breast cancer.

Greater coffee consumption was related to better survival of participants whose cancer had certain tumor markers:

  • ER-positive breast cancer
  • ER-negative breast cancer
  • IR-negative breast cancer
    • These cancers lack a type of Insulin growth factor-receptor called IR.
  • Luminal A breast cancer
    • These cancers are estrogen receptor-positive, progesterone receptor-positive and HER2-negative with low levels of the protein Ki-67.
  • Luminal B breast cancer
    • ER-receptor positive, PR-receptor positive and HER-negative with high levels of the protein Ki-67 or HER2-positive.

Breast cancer survival was not greater among participants who were high consumers of coffee and had IR-positive breast cancer or those with HER2-enriched (estrogen-receptor positive, progesterone-receptor positive, HER2-positive) or basal-like/triple-negative (estrogen receptor-negative, progesterone receptor-negative, HER2-negative) breast cancers. Not all tumors are tested for all of these markers.

 

Lack of impact of coffee consumption before breast cancer diagnosis

Coffee and tea consumption before breast cancer diagnosis was not linked to breast cancer-specific deaths or all-cause deaths. Whether participants drank lots of coffee before their breast cancer diagnosis did not increase or decrease their risk of breast cancer-related death (or all-cause death). Rather, coffee consumption after breast cancer diagnosis accounted for decreased risk of breast cancer deaths.

However, findings were different for participants who drank more coffee before their breast cancer diagnosis and then drank less coffee after diagnosis.

 

Decreasing coffee consumption after breast cancer diagnosis increased risk

Participants who drank more than two cups of coffee before cancer diagnosis and then drank no coffee after a breast cancer diagnosis had a 91% higher risk of death from breast cancer than participants who did not drink coffee before or after a breast cancer diagnosis.

Participants who drank more than two cups of coffee before cancer diagnosis and then drank less (0 to 2 cups of coffee each day) after breast cancer diagnosis had a 34% higher risk of death from breast cancer than participants who did not drink coffee before or after a breast cancer diagnosis.

Researchers cannot explain why this change in coffee consumption increased risk. Nor could they distinguish this from other possible factors that are varying in the same way.

 

Other factors may influence the risk of breast cancer death among coffee drinkers

Human research is complicated because researchers cannot always vary a specific aspect of a person's life or diet. Several things that vary at the same time are called confounding factors; it can be difficult to tell which factor is responsible for a particular effect on health.

In the case of coffee consumption and breast cancer deaths, researchers noted several confounding factors that with potential impacts that could not be separated. Participants with higher coffee consumption after diagnosis were more likely to:

  • drink alcohol
  • smoke
  • consume more animal fat
  • used aspirin more frequently after diagnosis

and less likely to:

  • have radiotherapy
  • have chemotherapy.

 

While researchers tried to account for the effect of these confounding factors, the effect they attribute to coffee or tea consumption may be in part because of these confounding factors.

Researchers noted that several factors did not contribute to the effects observed, including:

  • age
  • body mass index (BMI) after breast cancer diagnosis
  • stage of cancer
  • amount of coffee or tea consumed on average before breast cancer diagnosis

 

Strengths and Limitations

Overall, this was a well-designed and appropriately analyzed study. The researchers were careful to point out weaknesses of their interpretation as well as highlight major findings.

Strengths

  • A major strength of this study is that 8,900 participants were enrolled. Larger studies are typically more accurate because there is a greater chance of detecting differences when they occur.
  • Another strength is the regular follow-up on participants’ health. Researchers followed the health history and food and drink consumption history of participants every 4 years throughout the study rather than by asking participants to recall memories of health and diet history. This type of prospective study (looking forward in time) is considered better than a retrospective study (looking back in time) because the researchers have greater confidence that the results are accurate.
  • The time of follow-up was long (11.5 years on average) allowing researchers to have a comprehensive understanding of the coffee and tea consumption of the participants.
  • Self-reports of health and breast cancer diagnosis were validated with reviews of medical records and where needed, testing tumor tissue to verify cancer type.

 

Limitations

  • The biggest limitations of this study are confounding factors. Several factors (smoking, alcohol consumption, less use of chemotherapy and radiation therapy) vary in the same way that coffee and tea consumption do; if a person drank more coffee they also usually smoked more and drank more alcohol. While the researchers used statistical tools to ask whether these factors rather than coffee were responsible for the findings, concern remains that the decrease in the risk of breast cancer deaths may be from a combination of these factors in addition to coffee or tea consumption.
  • The study population was not diverse. The majority of participants were well-educated, non-Hispanic white women. These findings may not be generalizable to the more diverse U.S. population.
     

Context

A few smaller studies have also looked at coffee consumption after a breast cancer diagnosis. The findings in this study are similar to a prior study of 576 women with ER-positive cancer who were treated with tamoxifen, drank two or more cups of coffee a day and had improved survival. However, some previous research conflicts these conclusions: a study of 96 women saw worse survival with more coffee consumption.

Like this study, prior studies looking at coffee consumption before breast cancer diagnosis similarly saw no link to survival apart from one report of improved survival among nonsmokers with high coffee consumption.

Overall, this study builds on our knowledge about the impact of coffee and tea consumption on breast cancer.

 

Conclusions

High coffee consumption is linked to improved breast cancer-specific survival and overall survival. High tea consumption is linked to improved overall survival. Both decaffeinated and caffeinated beverages contribute to the improved survival observed. Breast cancer survivors may benefit from regularly drinking tea or coffee.

 

Share your thoughts on this XRAY review by taking our brief survey.
posted 8/31/21

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