Oral cancer has doubled the number of young people affected because of drinking, smoking and a unhealthy diet, warn experts.
Researchers at the Aberdeen University also found that cancers are becoming increasingly common among younger people.
The five-year study looked at 350 patients under the age of 50 with UADT cancers and 400 patients who did not have the diseases.
Almost nine in 10 of the cancers were caused by smoking drinking alcohol and/or a lack of fruit and vegetables in the diet-the factors already known to fuel the tumours in the elderly.
"Cancers of the upper aero-digestive tract are on the increase throughout the world and to date the increases have been greatest in young adults under the age of 50," the Daily Mail quoted Gary Macfarlane, lead author of the study.
"Our study aimed to determine whether smoking, alcohol consumption and low fruit and vegetable intake remained the most significant risk factors for UADT cancers in this age group, or whether other "novel" factors including genetics and infection could be relatively more important.
"The results of our study further emphasise that the message we need to be communicating to the public remains the same - that smoking, drinking and diet are the major triggers of these diseases at all ages," he said.