The Pap test is first introduced into physician's offices, enabling doctors to detect and begin treating cervical cancer before it has a chance to spread. Over the following decades, the Pap test is credited with driving down cervical cancer death rates in the U.S. and other wealthy countries. Yet cervical cancer remains a major cause of death in low-resource settings around the world, where access to screening and treatment is limited.

George Papanicolaou discovers that vaginal cell smears can reveal the presence of cervical cancer. This finding paves the way for the development of the first effective cancer screening test over the next 15 years. With refinements over the following decades, the Papanicolaou test (or Pap test, or Pap smear) remains the gold standard for cervical cancer screening and has been credited with reducing cervical cancer deaths by 70 percent in the U.S.