The results of the study, reported at a cancer conference in Chicago, could save tens of thousands of women’s lives each year in developing countries, where conventional pap smear tests and tests for HPV, which causes most cervical cancers, are too expensive.

The test used in the Indian study involved swabbing the cervix with a solution of diluted vinegar, which makes abnormal cells temporarily change color. This allows cancerous cells to be spotted early, which can save many lives – maybe up to 72,600 worldwide, researchers said.

The study in India was a hard slog in a country where women must often ask husbands or fathers for health care decisions. Social workers knocked on doors in slums to try to persuade women to be tested.

“We went to every single house in the neighborhood assigned to us introducing ourselves and asking them to come to our health talks. They used to come out of curiosity, listen to the talk but when we asked them to get screened they would totally refuse,” one of the social workers said. “The women were both scared and shy.”

One woman accused medical workers of trying to steal her kidney when she was examined, and a health worker was beaten by locals when women learned they would have to disrobe for the procedure.

But the persistence paid off. While the study was originally envisioned as lasting 16 years, researchers realized at 12 years there were conclusive results that lives were being saved.

Indian health officials now plan to expand the tests to a wider population of women.

This simple test, which can be administered by non-medically trained personnel, will save millions of lives over time. And that is a very good thing.