Head and neck cancer is the seventh most common cancer in the world. Both alcohol and tobacco use increase a person's risk of these cancers, so stopping smoking and drinking can reduce the chances of developing them. Diet can also help.

Coffee and tea consumption have been among the dietary factors seen as offering some protection against the risk head and neck cancer. That is why an international team of researchers studied the records from more than 9,500 cases of head and neck cancer, and 15,780 controls without cancer, to look at how much coffee and tea participants drank.

They found that drinking coffee and tea was protective. It reduced the risk of different types of head and neck cancer, including cancers of the mouth and throat.

Peoplee who drank more than four cups of caffeinated coffee a day had a 17 percent lower risk of developing head and neck cancer than those who drank less.

Study participants had filled out questionnaires about how many cups of caffeinated coffee, decaffeinated coffee and tea they drank every day, week, month and year.

Those who drank more than four cups of caffeinated coffee a day had a 17 percent lower risk of developing head and neck cancer than those who drank less. They also had a 30 percent lower risk of cancer of the oral cavity and a 22 percent lower risk of developing throat cancer.

Drinking three or four cups of caffeinated coffee a day was associated with a 41 percent lower risk of hypopharyngeal cancer, a cancer of the lower throat.

Decaf coffee reduced the risk of head and neck cancers, too, though at a lower rate. People who drank decaffeinated coffee had a 25 percent lower risk of developing cancer of the oral cavity than those who did not drink any coffee.

Tea drinkers had a 29 percent lower risk of hypopharyngeal cancer. People drinking only one cup of tea a day had a nine percent lower risk of developing head and neck cancer and a 27 percent lower risk of hypopharyngeal cancer.

In addition to caffeine, there are likely other bioactive compounds that contribute to the anti-cancer effects of coffee and tea, Yuan-Chin Amy Lee, senior author of the study, explained. Polyphenols, for example, compounds found in caffeinated and decaffeinated coffee and in tea, have antioxidative and anticancer properties that inhibit the growth and spread of cancer cells.

“Coffee and tea are very complex,” Lee, an investigator at the University of Utah's Huntsman Cancer Institute and an adjunct associate professor at the University of Utah School of Medicine, told TheDoctor, “So our findings support the need for more data and more studies about the impact coffee and tea can have in reducing cancer risk.”

A less welcome and unexpected finding was that people who drank more than one cup of tea a day had a 38 percent increased risk of developing laryngeal cancer. This may occur because theophylline, a bioactive compound in tea, reduces pressure in the lower esophageal sphincter, contributing to acid reflux and gastro-esophageal reflux disease or GERD. Because previous studies have found that GERD increases the risk of laryngeal squamous cell carcinoma, the researchers believe theophylline may increase the risk of laryngeal cancer by causing GERD.

Polyphenols found in caffeinated and decaffeinated coffee and in tea may also contribute to cancer protection. They have antioxidative and anticancer properties that inhibit the growth and spread of cancer cells.

More studies are needed to better understand the protective effects of coffee and tea. For example, this research was based on an analysis of 14 studies that were mostly done in North America and Europe, so the findings may not be generalizable to other populations such as in South America, Africa and Asia where coffee and tea consumption differs from that in Europe and the U.S. Participants were also not asked for information about the duration of their coffee or tea consumption or the concentration, temperature, types of coffee and tea they consumed or the processing technique used to brew their coffee or tea.

The study is published in Cancer.