Regular Pap smears improve the chances of surviving cervical cancer, according to Swedish research confirming the life-saving benefits of screening every three years during a woman's 20s, 30s and 40s.
The findings about the benefits of widespread testing every three years are particularly relevant for women in this country, where the U.S. Preventive Services Task Force last fall recommended that healthy women 21 to 65 undergo a Pap smear every three years, rather than continuing to make the test an annual medical ritual. The task force noted that overtesting has enormous financial and physical consequences for women.
Sweden is a good natural laboratory for studying cervical cancer survival for several reasons. It has a strong national screening program that calls women in for testing every three years from ages 21 to 50 and every five years from 51 to 60, maintains good databases tracking how they fare, and provides broad access to testing and care.
"This is an excellent study and helpful for the screening message," said Dr. Mark Einstein, director of gynecologic oncology at Montefiore Medical Center in the Bronx, N.Y. "In such a highly accessible health system as there is in Sweden with registries that are the envy of the world, this study shows that Pap testing impacts survival from cervical cancer. It also tells us that Pap tests are still an essential part of cervical cancer screening."
Einstein noted that cervical cancer used to be the No. 1 cancer killer of women in the early 20th century, but that after the adoption of widespread measures that today also include testing for human papillomavirus (HPV), a sexually transmitted infection responsible for the vast majority of cervical malignancies, as well as HPV vaccination, "cervical cancer does not even make the top 10 prevalent cancers in U.S. women anymore."
However, he said, "In the United States, more than half of women who get cervical cancer have never been screened or have been under-screened."
Swedish women diagnosed with cancer detected through a Pap screen within the previous six months had a better prognosis than those diagnosed because they came in with symptomatic cancer, the researchers from Uppsala University and the Karolinska Institute reported. In addition, women whose symptomatic cancer was diagnosed during the three or five years between regular tests fared better than symptomatic women who were overdue for repeat screening, they found.
Their results, based on a study of the 1,230 Swedish women diagnosed with cervical cancer between 1999 and 2001, and followed for an average of 8.5 years afterward, appeared online Thursday in the British Medical Journal.
The researchers sought to determine whether detection of cervical cancer by screening resulted in a better prognosis or just resulted in earlier diagnosis, and found that the prognosis indeed was better if the testing caught the cancer. Looking at the big picture, they found that screened women whose cancer was picked up by a Pap test had a higher so-called cure rate (meaning they survived cancer-free) than those whose cancers were found after they already had symptoms.
"This is an important observation because this was a prospective study with a decent-sized study group," said Dr. Matthew Anderson, a gynecologic cancer specialist at Baylor College of Medicine in Houston, Texas. "Outcomes are a whole lot better if you catch the disease early. It's more treatable, less likely to have developed metastases and can be treated less aggressively with likely fewer side effects and complications."
Study Doesn't Address More Frequent Screening
Anderson noted that the study "does little to address the value of cervical cancer screening more frequently than every third year. It does say that some minimum of regular screening is better than none."
Anderson also questioned the age at which Swedish women are tested every five years instead of every three years, because of the finding that half the women who died from cervical cancer within five years of diagnosis were older than 50.
"Given that women in Scandinavia or the United States who are alive at age 60 have a very good likelihood of being alive at age 80, this seems like a big price to pay for those women unlucky enough to develop a cervical cancer at age greater than 50. Critics would counter that the median age for cervical cancer patients is mid-40s, but the rate is clearly not zero after age 50 and the experience of these investigators supports that."