The Role of Green Tea in Lung Cancer Prevention and Treatment

EGCG in Green Tea and Cancer Risk, Growth, and Metastasis

content woman sipping a cup of green tea
Does green tea have a role in the prevention and treatment of lung cancer?. Photo©brickrena

Could green tea help in both the treatment and prevention of lung cancer? Along with the organic-natural-healthy food craze crossing the nation, you’ve likely heard at least mention of green tea. Whether or not green tea plays a role in maintaining health is an area of critical need in research - after all, other than water, green tea is the most consumed beverage worldwide.

Please note that green tea in the context of this article is for health promotion purposes alone and to give you a conversation starter for your doctor. Green tea in this setting is certainly not a substitute for any treatment but is being studied for its benefits as a possible add-on to conventional cancer care.

Understanding Green Tea

Green tea is made from the leaves of the plant Camellia sinensis. It differs from black tea (fermented tea) in that it is steamed before the leaves wilt; capturing many of its disease-fighting phytochemicals (plant chemicals) before the leaves can oxidize. The process of oxidation significantly reduces the amount of catechins in the tea - the compounds in green tea thought to have cancer preventive as well as other benefits.  

The catechins in green tea are powerful antioxidants, which likely accounts for some of their activity against cancer. Damage to DNA that takes place as a result of reactions involving oxygen - oxidative damage - is considered one of the mechanisms by which cancer forms. Antioxidants work by scavenging free radicals in the body to prevent the oxidative damage, that may, in turn, lead to the formation of cancer cells.

Cancer-Fighting Components in Green Tea

There are several major cancer-fighting substances in green tea.

Some of these include:

  • Epigallocatechin-3-gallate (EGCG)
  • Epicatechin
  • Epicatechin-3-sulfate
  • Epigallocatechin

Based on population statistics there are probably several components in green tea that may help prevent or treat lung cancer. Of these, epigallocatechin-3-gallate - EGCG - has been studied the most.

How May Green Tea Help Fight Cancer?

How may the components found in green tea help to both reduce the risk of cancer and treat it? In looking at the possible mechanisms it's important to remember that cancer is a complex disease. There are many critical steps that occur, first in the formation of cancer cells, and then to grow and maintain a tumor and have it spread. Thankfully, interrupting any of these steps along the way may help us fight lung cancer - the cancer which causes the most deaths in both men and women in the United States each year. 

A few of the steps involved in the onset and growth of a cancer include:

  • Cell transformation - The process by which a healthy cell becomes a cancer cell.
  • Cell division - Cells need to continually reproduce (divide) for the tumor to expand.
  • Avoiding cell death - Cancer cells need to avoid the process of apoptosis (programmed cell death) which healthy cells use when damaged or abnormal. Cancer cells become, in a way, immortal.
  • Ability to metastasize - Cancer cells need to, by definition, become "nonsticky" and travel to other regions of the body.
  • Ability to resist treatments - Cancer cells need to overcome (become resistant) to cancer treatments in order to continue to grow or recur.

To understand this in greater depth, check out this article on the differences between cancer cells and normal cells.

Green Tea and Lung Cancer Prevention - Cell Transformation

Population studies tell us that people who live in regions of the world where green tea consumption is the highest have a lower overall risk of developing lung cancer. Several large studies examining diet and cancer risk have also found a strong correlation between green tea intake and a reduced risk of lung cancer (among others.)

Why would this be?  Why would green tea offer a protective effect against cancer?

In order for a cell to become cancerous, a series of mutation in that cell's DNA need to take place. With lung cancer, the cause of these mutations may be smoking, but could also be exposure to radon in the home, a normal result of the body's metabolism, or any number of insults. The mechanism, however, is often the same - oxidative damage to DNA

In a few studies, heavy smokers were given 4 cups of green tea a day with the goal of decreasing DNA damage due to smoking. As noted above, smoking produces free radicals which can in turn cause "oxidative damage" to DNA, eventually resulting in the development of cancer cells. To measure oxidative damage, these researchers had the volunteers in the study give urine samples. Testing urine for the amount of a compound called 8-hydroxydeoxyguanozine (8-OHdG) gives an estimate of the amount of oxidative damage that has occurred in the body. The smokers who drank green tea had on average 30 percent less oxidative damage than non-tea drinkers based on this measure.

This was just one method of many by which green tea has been evaluated for its potential to reduce cancer risk, but early studies seem to support that there are scientific reasons for what we see in population studies. 

Possible Role of Green Tea in Lung Cancer Treatment

There are several different pathways in the growth and spread of lung cancer that have been evaluated in order to see if green tea (EGCG) may have some benefit. These include altering signals not only in cells becoming a cancer cell but in proliferation, apoptosis (cell death,) and spread (metastasis) of cancer cells.

Inhibition of cell division and proliferation

If you can stop cells from dividing, a cancer can't proliferate - make new cells and grow in size. This is the concept behind chemotherapy drugs, most of which work to inhibit one of the steps in cell division.   Cancer cells may be at different points in the process of dividing, and this is the rationale for using a combination of drugs - to hit different places along the path of division so you can kill a cancer cell no matter which stage it is in.

Several studies have found that components in green tea, particularly EGCG, have worked in a number of ways to cause "cell cycle arrest" - in other words, stopping the process of a cancer cell dividing. The interesting thing with green tea is that it often interrupts this process without affecting cell division among normal cells.  

Induction of apoptosis

One important difference between healthy cells and cancer cells is that healthy cells die when they are damaged and cannot be repaired. Cancer cells have found a way to bypass this step of programmed cell death called apoptosis. In a few studies, it was found that green tea worked to induce apoptosis of lung cancer cells.

Inhibition of Angiogenesis

In order for cancers to grow, they need to create new blood vessels to supply their nutrients. This process is called angiogenesis - for the root words "new blood."  We have learned that nicotine can stimulate angiogenesis in cancer cells. It was found that EGCG inhibited nicotine-induced angiogenesis in cancer cells.

Inhibition of Metastasis

Several studies with lung cancer cells as well as other cancers have found that compounds in green tea may inhibit the ability of cancer cells to metastasize (spread) to other regions. Since most deaths from cancer occur due to metastases, this is an encouraging finding and an active area of research.

Enhancing chemotherapy 

The possible benefit of green tea components enhancing chemotherapy was first noted widely when components of green tea appeared to sensitize liver cancer cells to the anticancer effects of the chemotherapy drug Adriamycin (doxorubicin). In other words, the chemotherapy drug worked even better to kill cancer cells when combined with EGCG. In lung cancer cells grown in the lab, EGCG improved the ability of Platinol (cisplatin) to kill human non-small cell lung cancer cells. Since platinum-based chemotherapy drugs such as Platinol are used frequently with lung cancer patients, this is also an exciting finding.

Renewed sensitivity to chemotherapy - Cancer stem cells?

The concept of cancer stem cells, a hierarchy of cancer cells in which some cells act like the generals in the army, and more resistant to treatment, has been a hot topic in oncology and was proposed as a possible way in which green tea played a role in a recent study. This concept of stem cells is one theory to explain why cancer may recur after even a lengthy period of time. It's thought that perhaps these cells lay "dormant" and hence aren't eliminated with current chemotherapy drugs.

Researchers looked at studies with colon cancer and started asking questions. In the studies, it was found that the equivalent of 10 cups a day of green tea could reduce the recurrence of colon adenomas by 50 percent. (About 1 in 10 adenomatous polyps become cancerous in time.) Using this idea, they decided to see if green tea catechins might enhance the effect of anticancer drugs when given in combination - if EGCG could help overcome chemotherapy resistance which almost invariably develops. Looking at the results of 42 studies with lung cancer cells grown in the lab and with animals, they found that adding the green tea compounds to the anticancer drugs resulted in an average tumor reduction of about 70 percent. Their conclusion was that green tea may inhibit self-renewal of cancer stem cells.

Bottom line

Other than population studies, most studies on green tea and its compounds have been done in the lab and with animals, but results so far have been exciting. If you enjoy a cup of tea to relax, it may be worth talking to your oncologist to see if it's okay to continue doing so (or developing a taste for tea) during treatment.

Side Effects/Interactions

Green tea is usually tolerated very well, and its safety has been tested even with relatively high doses of green tea extract. Researchers tested volunteers with daily doses of green tea for 4 weeks. At the equivalent of 16 cups per day, the volunteers had no change in their blood counts or blood chemistry analysis. Side effects were similar to those of people given a placebo instead and ranked only as mild gas, upset stomach, heartburn, headache, and dizziness.

Green tea does contain caffeine, though less than black tea or coffee. If you are sensitive to caffeine or struggle with anxiety or insomnia, green tea may not be your cup of tea.

For people with anemia, especially during chemotherapy, it's important to know that green tea may lower the absorption of iron. This can be avoided by drinking green tea at a time separate from meals, and waiting at least one hour after meals to drink your tea.

For People Receiving Chemotherapy

It's very important to talk with your oncologist if you are in the midst of cancer treatment. Some nutritional supplements, as well as vitamin and mineral supplements, may interfere with chemotherapy. Green tea did not appear to interact with most anticancer medications in the studies reviewed (and rather, enhanced the effects of chemo in a few) with the exception of a few. An animal study suggested that green tea extract could possibly decrease the effects of Velcade (bortezomib.) In another study, the extract was found to inhibit the activity of Sutent (sunitinib) - though yet another study found that it enhanced the effect of this drug. Neither of these drugs is ordinarily used for lung cancer. Camptosar (irinotecan) is a chemotherapy drug which is sometimes used for lung cancer. One study found that this drug was not affected by green tea extract, but another found that ECGC extract reduced the level of Camptosar significantly. In addition, some studies have found that ECGC extract can affect drugs metabolized by the enzyme CYP3A4 in the liver, while others have not found an effect, though also noted was that the ECGC content of different extracts varies widely. Unless your oncologist believes it could help, it's probably best to avoid green tea extract supplements while on chemotherapy, especially treatments which include irinotecan.

The new immunotherapy medications appear to work best when there is inflammation near a tumor. Since green tea has anti-inflammatory functions, it is might be wise to hold off on the tea when using these drugs - but again that's a conversation you'll need to have with your oncologist. Medicine is changing rapidly and new studies are reported every day.

How Much Green Tea?

If you’ve heard the jokes about lab rats consuming the equivalent of 80 pounds a day of a chemical to see if it causes cancer, you may be wondering how much green tea is best.  And that is a good question. Some of the studies on green tea have tested large amounts on lab animals - for example, the equivalent of drinking 20 or 30 cups a day. Others have looked at more "normal" levels of tea consumption, even the effect of one cup per day. There's not a magic number, but some investigators claim that an ideal would be 4 cups per day.

Some people choose to get their green tea in the form of dietary supplements. If you and your oncologist decide to do this (always, always talk to your oncologist before taking any supplement) be aware that studies have found that the information provided on these supplements is not necessarily very accurate. Since dietary supplements have little regulation in the United States, the amount of the "good" green tea compounds mentioned on the label may not be the same as what is actually present in the product. If you do go this route, choose a good quality product, and keep in mind that you may pay for what you get.

How to Prepare Green Tea for Maximum Benefits

To get the maximum benefits of the components of green tea, it helps to know how to prepare and serve it. For example, the ready-to-drink green tea drinks you pick up at the grocery store have very low levels of EGCG. With iced tea, it's hard to know what the content of catechins would be unless you know the process by which it is brewed.

Check out these tips on how to best brew green tea for the health benefits. Using boiling water helps extract the catechins, and longer steeping times may also result in more of the good stuff in your cup. For those who are sensitive to caffeine, decaffeinated green tea is available. Unfortunately, it appears that the decaffeinating process also reduces catechins such as EGCG.

How you serve your green tea can make a difference as well. It's a good idea to leave out the cream, as dairy products bind EGCG preventing its absorption. Lemon does the opposite, so adding a touch of lemon to your tea may do more than enhance the flavor.

A Word About Foods vs Supplements

Before you finish reading don’t immediately grab your keys, jump in your car, and run to the nearest health food store to buy a supplement of green tea. We still don’t know if the protective and cancer-fighting properties of green tea lie in the compounds mentioned if the effect is related to another chemical in green tea not yet discovered, or results from a combination of several compounds that work together or against each other. Getting a nutrient via food can be quite different than getting it through a supplement. For example, it was found that men who ate diets high in the phytochemical (plant-based chemical) beta-carotene had a substantially lower risk of developing lung cancer. When researchers gave volunteers beta-carotene as a supplement, however, the beta-carotene supplement not only failed to prevent lung cancer, but the opposite occurred. Men taking beta-carotene supplements had a higher risk of developing lung cancer than those who did not.

Other Health Benefits

Green tea appears to have health benefits in addition to what has been found in the cancer arena. It's been looked at for its benefits on the heart and its ability to improve the ratio between good and bad cholesterol. For weight loss, it appears that green tea increases metabolism. ​There's more, and based on the number of clinical trials currently in process, we will likely be hearing more in the near future.

Next Steps

If you're reading this with an interest in prevention, check out these superfoods that may lower the risk of lung cancer. If you're living with cancer, take a look at these lung cancer-fighting foods. And it can't hurt to take a peek at this list of things that may improve lung cancer survival that your doctor might not mention.


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