BOSTON (CBS) – Researchers in Boston have found that alcohol is a major contributor to cancer deaths and years of potential life lost.

Dr. Timothy Naimi, at Boston University School of Medicine, says this is the first time in 30 years that researchers have looked closely at alcohol and cancer deaths.

“When it comes to alcohol consumption and cancers, clearly excessive drinking is the riskiest type of drinking,” Dr. Naimi said. “But when it comes to cancer, there is no safe level of alcohol consumption.”

Researchers found that alcohol resulted in about 20,000 cancer deaths annually, accounting for about 3.5 percent of all cancer deaths in the U.S.

“Even what some people would consider moderate amounts are important risk factors for some cancers,” said Naimi.

Previous studies have shown that alcohol consumption is a significant risk factor for cancers of the mouth, throat, esophagus and liver. More recent research has shown that alcohol also increases the risk of cancers of the colon, rectum and female breast.

Breast cancer was the most common cause of alcohol-related cancer deaths in women.

“Alcohol is a big preventable cancer risk factor that has been hiding in plain sight,” said Naimi.