Researchers made it possible to foresee which breast cancer sufferers will be helped by a leading cancer drug called Tamoxifen, they said on Saturday.

The results of a study on more than 1,000 women showed that lowering breast density by taking Tamoxifen also reduced the risk of tumors coming back. It has been already demonstrated that women with dense breasts are more likely to develop breast cancer, compared to women who have less non-fatty tissue, researchers reported at a breast cancer conference held in San Antonio, Texas.

After about 12 months of taking the drug, which has been used for 25 years to treat breast cancer in women and men, participants in the study whose breasts became less dense had a 63 percent diminished risk of developing the disease.

On the words of Jack Cuzick of the Wolfson Institute of Preventive Medicine in London, "it is important to find a way to predict who will respond to Tamoxifen, and changes in breast density may constitute an early indicator of benefit."

An estimated 10 percent of women have dense breasts. The risk of breast cancer is four up to five times higher among these women, compared to the risk in those without dense breasts, Cuzick said. Physicians often confront with difficulties as far as reading dense breasts on mammograms concerns.

Cuzick added that if a woman's breast density didn’t alter during the 1-year treatment, she was much more prone to develop the deadly disease notwithstanding the use of Tamoxifen.