Hello, I am @cancerdoctor, a radiation oncologist in South Korea.
I had worked in Seoul National University Hospital in Korea, and I am working for public health now.
I am here in order to provide several important note regarding cancer.
It's getting colder every day, so it seems that hot coffee comes to people's mind when fighting off the winter chill. I enjoy my share of coffee everyday, and I am currently preparing for a Barista certification as part of my hobby.
Which brings me to today's note; I want to talk about COFFEE and CANCER.
What comes into your mind when you think of coffee and health?
Coffee is a double edged sword. Coffee contains about 50-150 mg of caffeine in a cup of coffee. The caffeine affects our body in many ways. It can aggravate gastrointestinal diseases, act as diuretics, and awake our mind.
There have been some debates about the effect of coffee to hypertension or other cardiovascular diseases. However, there is a report showing that people who drink three cups of coffee everyday have lower death rates and incidences of cardiovascular diseases, showing us that moderate amout of coffee is helpful to our body.
Then, how about cancer? Can coffee cause cancer, or prevent cancer?
There are various kinds of anti-oxidants and phenols in coffee, which have anti-cancer effects shown by laboratory experiments. Caffeine improves glucose metabolism and insulin intolerance when drinking coffee over time. This can lead to a prevention of diabetes mellitus and cancer as well.
2. Prostate cancer
There have been various reports showing a protective effect for prostate cancer. Most of the studies published before the 2000s concluded that there is no correlation between coffee and cancer. Yet, recent prospective studies have shown that coffee reduces a risk of prostate cancer.
J Natl Cancer Inst. 2011 Jun 8; 103(11): 876–884.
Coffee Consumption and Prostate Cancer Risk and Progression in the Health Professionals Follow-up Study
Kathryn M. Wilson, et al.
"We observed a strong inverse association between coffee consumption and risk of lethal prostate cancer. The association appears to be related to non-caffeine components of coffee."
The study above is a long term clinical trial since in United States. According to their reports in 2011, coffee consumption was related to a lower risk of lethal prostate cancer, and possibly related to anti-cancer effects due to the non-caffeine components of coffee.
3. Stomach cancer
Excessive intake of coffee can aggravate gastrointestinal disease such as gastritis, gastric ulcer, and so on. For this reason, the relationship between coffee and stomach cancer has been questioned. However, most of studies investigating coffee and stomach cancer have shown that there is no significant correlation between coffee consumption and stomach cancer.
4. Colorectal cancer
It is difficult to make a conclusion in terms of colorectal cancer. In some reports, there was no relationship between coffee and colorectal cancer, but others show a significant relationship. There's a hypothesis that coffee can stimulate a bowel movement and decrease secretion of the bile duct and sterols, which might prevent damage of mucosa. Also, caffeine can decrease insulin intolerance as well as flavonoid in coffee act as an anti-oxidant, which coud aid in the prevention of developing cancer.
Coffee consumption and risk of colorectal cancer: a meta-analysis of case–control studies
Carlotta Galeone, et al.
"The reduced risk was consistent across study design (hospital vs. population based), geographic area, and various confounding factors considered. It may reflect a real protection but also partly or largely be due to reverse causation, i.e. decreased coffee consumption among cases following the onset of bowel symptoms."
This study is a meta-analysis which collected meaningful studies about the correlation between coffee consumption and colorectal cancer. According to the study, people who had drunk coffee over long time had lower risks for colorectal cancer regardless of other factors.
However, the authors also warned that the results may have been disturbed, because people usually stop drinking coffee when they have bowel problems such as stomachache, diarrhea, abdominal soreness, etc.
JNCI: Journal of the National Cancer Institute, Volume 97, Issue 4, 16 February 2005
Coffee, Tea, and Caffeine Consumption and Incidence of Colon and Rectal Cancer
Karin B. Michels, et al.
"However, participants who regularly consumed two or more cups of decaffeinated coffee per day had a 52% (95% CI = 19% to 71%) lower incidence of rectal cancer than those who never consumed decaffeinated coffee."
The National Institutes of Health in US established large prospective investigation systems by collecting data from nurses and health professionals. The study above analyzed a correlation between coffee consumption and incidences of colorectal cancer with the catalogued data. They reported that caffeinated coffee was not related to the incidences of colorectal cancer, but those who regularly drank decaffeinated coffee had lower risks of rectal cancer.
5. Liver cancer
There have been many studies showing the effectiveness of coffee preventing incidences of liver cancer.
Gastroenterology, Volume 132, Issue 5, May 2007, Pages 1740-1745
Clinical–liver, pancreas, and biliary tract
Coffee Consumption and Risk of Liver Cancer: A Meta-Analysis
Susanna C.Larsson, Alicja Wolk
"Overall, an increase in consumption of 2 cups of coffee per day was associated with a 43% reduced risk of liver cancer (RR, 0.57; 95% CI, 0.49–0.67)"
In the study above, the investigators analyzed five large studies with an estimated total of 240,000 people, and reported that people who had drank 2 cups of coffee per day was associated with a 43% reduced risk of liver cancer.
6. Breast cancer
We expected that coffee could lower a risk of breast cancer, but most of the studies concluded that there is no significant correlation between coffee consumption and incidences of breast cancer.
Cancer Genetics, 19 July 2005
Coffee consumption and breast cancer risk among BRCA1and BRCA2 mutation carriers
André Nkondjock, et al.
"These results suggest that among women with BRCA gene mutation, coffee consumption is unlikely to be harmful and that high levels of consumption may in fact be related to reduced breast cancer risk"
Nevertheless, according to recent reports including the study above, among those with the BRCA gene mutation, high coffee drinkers who had 6 or more cups of coffee per day had a lower risk of breast cancer. The BRCA gene mutation is the most well-known gene mutation causing breast cancer. People who have the BRCA gene mutation have a risk for breast cancer that ranges from 65% to 90%. This study implied that coffee could be helpful to people who are susceptible to breast cancer. Coffee is an important source of phytoestrogen, which might have an anti-cancer effect to high risk women for breast cancer.
7. Pancreatic cancer
Cancer Genetics, 19 July 2005
Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective
World Cancer Research Fund & American Institue for Cancer Research
"There is ample evidence, including prospective data, which is consistent and with low heterogeneity, and which fails to show an association. It is unlikely that coffee has any substantial effect on the risk of pancreatic cancer."
Some researchers have said that coffee can be a risk for pancreatic cancer back in the 1980s. There have been dozens of studies about this subject since. Some showed no effect for risk, some even showed a non-significant increased risk, and others displayed increased risk or mortality. According to a report by World Cancer Research Fund and American Institue for Cancer Research, coffee is unlikely to have any substantial effect on the risk of panceatic cancer.
Today, I discussed how coffee affects cancer; however, we cannot say that coffee is ultimately good or bad for cancer. But at least coffee is not significantly harmful when it comes to cancer.
So I'll be enjoying a nice cup of coffee today like always.
- Kathryn M. Wilson, Julie L. Kasperzyk, Jennifer R. Rider, et al. Coffee consumption and prostate cancer risk and progression in the health professionals follow-up study. J Natil Cancer Inst. 2011 Jun 8; 103(11):876-884.
- Karin B. Michels, Walter C. Willett, Charles S. Fuchs, et al. Coffee, tea, and caffeine consumption and incidence of colon and rectal cancer. JNCI, 2005 Feb; 97(4):282-292
- Carlotta Galeone, Federica Turati, Carlo La Vecchia, et al. Coffee consumption and risk of colorectal cancer: a meta-analysis of case–control studies. Cancer Causes & Control, 2010 November, 21(11):1949-1959.
- Susanna C.Larsson, Alicja Wolk, Clinical–liver, pancreas, and biliary tract. Coffee Consumption and Risk of Liver Cancer: A Meta-Analysis, Gastroenterology, 2007 May, 132(5):1740-1745.
- Karin B. Michels , Lars Holmber, Leif Bergkvist, et al. Coffee, Tea, and Caffeine Consumption and Breast Cancer Incidence in a Cohort of Swedish Women. Ann Epidem, 2002 Jan, 12(1): 21-26.
- André Nkondjock, Parviz Ghadirian, Joanne Kotsopoulos, et al. Coffee consumption and breast cancer risk among BRCA1 and BRCA2 mutation carriers. Cancer Genetics. 2005 Jul, DOI: 10.1002/ijc.21296.
- World Cancer Research Fund & American Institue for Cancer Research. Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective. 2007.