Professor Yosef Shiloh, of Tel Aviv University's Sackler Medical School, has won the prestigious Clowes Award presented by the American Association for Cancer Research, it was announced this week.

This is the first time the AACR, the world's largest organization for cancer research, has given this award to an Israeli researcher.

"Professor Shiloh is an international leader in his field and an extraordinary scientist," AACR director Dr. Margaret Foti wrote in the explanation for awarding him the prize. "His work has launched a scientific revolution and opened up new horizons in the understanding of how the living cell copes with DNA damage, which is among the main factors in cancer."

Shiloh will receive the prize, which includes a $10,000 grant, a commemorative plaque, and funding to attend with a guest the AACR Annual Meeting in Orlando Florida in April.

Shiloh has devoted his career to research ataxia telangiectasia (A-T ), a rare, neurodegenerative, inherited disease that affects many parts of the body and causes severe disability. In Israel it is manifested mostly among people of North African origin and the Palestinian and Bedouin communities.

Shiloh has made several discoveries that contributed to understanding the disease, including discovering the defective gene causing it. This enabled detection of the disease in the early stages of pregnancy and paved the way to understanding its basis - a defective DNA damage response. Shilo said on Monday that he was very surprised to learn he had won the prize.

"I knew of my nomination but gave it a very small chance," he told Haaretz. "Out of the 50 winners preceding me, only four were not U.S. citizens."

Shiloh began researching A-T in 1977 after meeting a family from the Negev whose four children suffered from the disease. His work focused on the mechanisms that enable the cell to overcome DNA damage caused by various environmental factors such as radiation, chemicals in food and pollutants.

This damage is common in healthy people as well, but it is repaired by complex defense mechanisms, which are vital to preserving cell life and preventing cancer. These defense mechanisms, however, are not activated in A-T patients.

"Our great hope is that understanding the complex defense mechanism will enable new ways of treating the disease and other diseases caused by failures in our defense from DNA damages," Shiloh said.