Hot Tea and Increased Cancer Risk
Study Links Tea Temperature With Cancer of the Esophagus
Mar 29, 2009
In a study published this month in the British Medical Journal, a group of scientists studying the patterns of tea drinking and esophageal cancer found that both temperature and time post pouring greatly impact the risk of esophageal cancer.
The team, Islami F. et al, of the Digestive Disease Research Center, Shariati Hospital, Tehran University of Medical Sciences in Tehran, Iran, selected the area of Northern Iran (specifically the province of Golestan), to run the study because it has one of the highest rates of esophageal (oesophageal) squamous cell carcinoma in the world. Large amounts of tea are consumed in this area and other risk factors of smoking and alcohol use were low. It was also noted that cases of esophageal cancer (of the squamous cell carcinoma type) did not differ between sexes as is generally the case.
Esophageal Cancer Rate And Survival Statistics
- There are over 500,000 deaths worldwide from esophageal cancer.
- 14,280 cases of esophageal cancer are diagnosed annually in the United States with 16,470 new cases diagnosed per year.
- Survival rates vary based on the stage at diagnosis.
- The American Cancer Society has reported that 18% of white patients and 11% of African-American patients survive at least 5 years after diagnosis (this varies with stage).
- Five-year survival rates (percent of patients surviving five years after diagnosis) of 15.6% in the United States, 12.3% in Europe, and 31.6% in Japan have recently been reported.
Esophageal Cancer Risk Factors
Risk factors include the following:
- Older age - Most cases of esophageal cancer occur in those between 55 and 70 years of age.
- Sex - Men are more likely to be diagnosed than women.
- Race - In the United States, blacks are at higher risk for the squamous cell type and whites are at a higher risk for adenocarcinoma of the esophagus.
- Poor diet (diet low in fruits and vegetables).
- Preexisting Barrett's esophagus condition - Patients with Barrett's condition of the esophagus suffer from long term gastric reflux causing severe irritation with an increased risk of esophageal cancer.
- Smoking
- Alcohol use
- Flushing with alcohol use - a recent study found a relationship between those who experience facial flush when drinking alcohol and an increased incidence of cancer of the esophagus.
- Prior radiation treatment - Previous radiation treatment in general esophageal area.
- Occupation - A career in dry cleaning, mining, granite work, sandstone, brick, concrete and/or tile work increases the risk primarily due to continued exposure to silica dust and dry cleaning solvents.
Types of Esophageal Cancer
The two most common forms of esophageal cancer are
- Squamous cell carcinoma (also called epidermoid carcinoma) - most often occurring in the upper and middle esophagus. Squamous cell carcinoma is the most common esophageal cancer in the black population in the United States and of all esophageal cancers worldwide.
- Adenocarcinoma - usually forming in the lower part of the esophagus, near the stomach. Adnocarcinoma is the most common esophageal cancer in the white population of the United States and has increased by 50% in blacks and 450% in whites in the last twenty years.
Other types include - sarcoma, lymphoma, small cell carcinoma and spindle cell carcinoma. As well as metastasis from breast or lung cancers.
Esophageal Cancer Symptoms
Symptoms of esophageal cancer may include some or all of the following:
- Difficulty and pain when swallowing
- Weight loss
- Pain in the chest
- Coughing
- Hoarseness
- Indigestion
- Heartburn
Tea And Cancer Study Method
The investigators in Iran compared proven cases of esophageal squamous cell cancers against a neighborhood control group and then also in a larger group of over 48,000 tea drinkers with details as follows:
- There were 300 proven cases of esophageal squamous cell cancer.
- The proven cases were matched with 571 neighborhood controls and assessed.
- A group of 48,582 were then entered into the cohort study - 98% drank black tea regularly, an average of one liter per day.
- 39% drank tea at temperatures of less than 60 degrees celcius.
- 38.9% at 60-64 degrees celcius.
- 22% at 65 degrees celcius or higher.
Tea And Cancer Study Results
- Results showed that drinking hot tea or very hot tea was associated with a significant increased risk of esophageal cancer.
- Drinking tea two to three minutes after pouring or less was associated with a significantly increased risk of squamous cell cancer of the esophagus (less than two minutes after pouring associated with a five fold higher risk).
- Drinking hot tea (65-69 degrees C) was associated with twice the risk of esophageal cancer when compared to the group drinking lukewarm tea (65 degrees C or less).
- Drinking very hot tea (70 degrees C or more) was associated with a remarkable eight fold risk.
Tea And Cancer Study Conclusions
Drinking hot tea was strongly associated with a higher risk of esophageal cancer (squamous cell carcinoma), with higher risks associated as tea temperatures increase.
Letting tea sit after pouring, for longer than three minutes, can significantly lower the risk of squamous cell carcinoma of the esophagus.
Additional Sources:
Science Daily
WebMD
National Cancer Institute
Mayo Clinic
News-Medicine.net
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