Cervical Cancer Screening: Too Many Are Left Unprotected

A meta-analysis by Spence and colleagues published in Preventive Medicine shows that undergoing Pap smears irregularly or never was the primary explanation for the development of invasive cervical cancer, followed by false negative tests and poor follow-up of abnormal results.

Papanicolaou and Traut first reported the usefulness of the Papanicolaou smear (''Pap test") for detecting neoplastic cervical cells in 1943. A smear of cells of the uterine cervix indicating the progression of the cancer's growing malignity provided a powerful screening tool that became rapidly used after WWII without its efficacy being evaluated in a randomized control trial. In the United States, the Pap test is credited with having halved the annual cervical cancer incidence rate (from 17.2 to 8.0 per 100,000) and mortality rate (from 6.2 to 2.9) from 1973 to 1999.

In 2000, 83% of U.S. women age 18 and older who had not had a hysterectomy reported having had a Pap test within the past 3 years. The recent discovery of a vaccine against human papillomavirus (HPV), the main cause of cervical cancer, opens the way to the primary prevention of the disease.

The natural history of cervical cancer progression combined with the availability of an HPV vaccine and an effective screening test indicate that eradication of the disease is a plausible objective.

To reach that goal, however, it is important not to give up on the minority of women who do not fully benefit from available prevention methods and unfortunately fail to be reached by health promotion messages. Dr. Eduardo Franco, the study's principal investigator, commented on the findings: "Cervical cancer is a sentinel disease of inequity. The socio-economic disparity already seen with availability of screening could aggravate if vaccination fails to reach the daughters of women at greatest risk. Like mothers, like daughters; the latter unvaccinated and unprotected by screening will eventually contribute to the sad reality of cervical cancer statistics in the future. The solution is to adopt vaccination and screening as universal strategies, with the latter modified to make cost-effective use of limited resources."

The article, "Process of care failures in invasive cervical cancer: Systematic review and meta-analysis" appears in Preventive Medicine, Volume 45, number 2-3, August-September 2007, published by Elsevier.