Drinking one alcoholic drink daily as well as being overweight can increase the risk of developing breast cancer, warns a study of over two lakh women.

"That means that consequently, even relatively small preventable proportions translate into large numbers of preventable breast cancers," said Maarit Laaksonen, from the University of New South Wales in Australia.

Over the next decade, drinking alcohol will lead to 13 per cent increase of breast cancer cases in pre-menopausal women and six per cent in post-menopausal breast cancers. Being overweight or obese will contribute to 13 per cent cases.

Together, these modifiable risk factors -- regular alcohol consumption and excessive weight gain -- will be responsible for nearly 30,000 cases of breast cancer by next decade, noted the study published in the International Journal of Cancer.

Further, the use of menopausal hormone therapy was found to account for seven per cent of post-menopausal breast cancers, with over 90 per cent of this burden caused by a long-term use. 

Similarly, long-term use of oral contraceptives accounted for seven per cent of pre-menopausal breast cancers.

However, it is not recommended that women restrict their use of oral contraceptives as they are actually cancer-protective and provide long-term protection against endometrial and ovarian cancers, suggesting that the potential benefits, including reproductive benefits, outweigh the harms, Laaksonen said, adding that further studies are needed to confirm the results. 

Maintaining a healthy weight and not consuming alcohol regularly could help prevent thousands of breast cancer cases, he suggested.