A simple vinegar test slashed cervical cancer death rates by one-third in a remarkable study of 150,000 women in the slums of India, where the disease is the top cancer killer of women.

Doctors reported the results Sunday at a cancer conference in Chicago. Experts called the outcome "amazing" and said this quick, cheap test could save tens of thousands of lives each year in developing countries by spotting early signs of cancer, allowing treatment before it's too late.