Papanicolaou smear screening and cervical cancer. What can you expect?

More than 90% of the total female population of three Swedish counties between the ages of 30 and 59 years, 53% of women between 60 and 69 years, and 25% of women older than 70 years were screened for cervical cancer with the Papanicolaou smear over a ten-year period. The uniqueness of the study is that in Sweden it is possible to follow up the entire population during their lifetimes via a population register, which has its roots in the 17th century, natural to Swedes but almost incomprehensible in the United States or United Kingdom. Every Papanicolaou smear taken was computer recorded and linked on an individual level to the cancer registry. There were 207,455 women followed up for ten years. No women were lost to follow-up. There was a 75% decrease in invasive cervical cancer incidence among women who had smears taken at least once during the ten-year period. Among those women who had never had smears taken, the incidence of invasive cervical cancer was four times as great as among those women who had been examined at least once. We estimate that the system proposed by Swedish Medical Board (at least one smear every three years) for cervical cancer screening can reduce the incidence of invasive cervical cancer to a level between one and five cases per 100,000 women per year in a completely screened population.