An inexpensive vinegar cancer test cut the rate of cervical cancer deaths by one-third in the slums of India, a study found. At a cancer conference in Chicago, doctors said the vinegar cancer test spots early signs of cancer. The test could save tens of thousands of lives in developing countries. Cervical cancer is a top killer of women in India. India has nearly one-third of the world’s cases of cervical cancer, more than 140,000 each year.

A vinegar cancer test is a low-cost alternative for countries that can’t afford such screening tools as pap smears and tests for HPV, the virus that causes a majority of cervical cancers. The study found that the cervical cancer death rate was cut by 31 percent. Researchers estimate the test could prevent 22,000 deaths in India and 72,600 worldwide annually. The introduction of pap tests and tests for HPV significantly reduced the incidence of cervical cancers in the U.S. A pap test involves examining a cervical swab and screening it for abnormal cells linked to potentially pre-cancerous and cancerous processes.

Dr. Ted Trimble of the National Cancer Institute in the U.S., the main sponsor of the study, said ‘‘That’s amazing. That’s remarkable. It’s a very exciting result.’’

The test can be performed by local people with just two weeks of training. The test is low-tech. It is a visual examination. People are taught to swab the cervix with diluted vinegar, which can make abnormal cells briefly change color. It doesn’t require fancy lab equipment.

Dr. Surendra Shastri of Tata Memorial Hospital in Mumbai, who led the research, said ‘‘It’s just not possible to provide Pap smear screening in developing countries. We don’t have that kind of money.’’

The testing began in 1998 when researchers enrolled 75,360 women to be screened with the vinegar cancer test every two years. The control group consisted of 76,178 women who were given cancer education ad vouchers for a free Pap test, though researchers briefly came under fire from the U.S. Office for Human Research Protections for not adequately informing participants in the control group about Pap tests for screening. Both groups of women got free hospital treatment if tests found cancer. The study was planned for 16 years, but after 12 years it showed lives were being saved with the screening. The control group was also offered screening. Over 99 per cent of cases of cervical cancer are caused by HPV.

Government officials in India are already making plans to expand the vinegar testing to a wider population.