Relatively small lifestyle changes could cut the number of cancer diagnosis per week in the U.K. by 2,500, according to a new study from Cancer Research U.K. 

That equates to more than 135,5000 cases a year, or 37.7% of all cancers diagnosed annually. 

Smoking continued to be the single largest preventable cause of cancer, representing nearly 18% of all cases in men and 12.4% of all cases in women. 

Obesity is the next largest preventable cause of cancer, with about 6.3% of cases being tied to excess weight. About 7.5% of female diagnoses are tied to obesity while that number dips to 5.2% in men. 

The third largest preventable cause of cancer is overexposure to UV radiation from the sun and tanning beds. 

Rounding out the top preventable causes of cancer in the U.K. are alcohol consumption, lack of fiber and outdoor air pollution. 

"Obesity is a huge health threat right now, and it will only get worse if nothing is done. The U.K. Government must build on the successes of smoking prevention to reduce the number of weight-related cancers. Banning junk food TV adverts before the 9 p.m. watershed is an important part of the comprehensive approach needed," said Professor Linda Bauld, Cancer Research U.K.'s prevention expert.