A Critical Evaluation of the Pap Test and Its Role in Reducing Cervical Cancer Deaths
Posted by medconsumers on March 1, 2007
Widespread use of the Pap test has successfully reduced cervical cancer incidence and mortality. This bit of medical wisdom has largely gone unchallenged with one noteworthy exception in 1978, when Anne-Marie Foltz and Jennifer L. Kelsey co-authored “The Annual Pap Test: A Dubious Policy Success” in the Milbank Memorial Fund Quarterly. This critique is worth recalling today, now that the Pap test is an integral part of the discussion surrounding the merits of the new HPV vaccine. Many consumer advocates who are against mass HPV vaccinations see Pap testing as the safer alternative.
Would that things could be that simple.
The Pap test’s role in the much-heralded “dramatic” decline in the cervical cancer death rate is overstated, according to Foltz and Kelsey, because the rate began to drop well before the Pap test became widely used. Moreover, they report that estimates of the effect of hysterectomy on this decline vary from 10% to 25%. (Hysterectomy involves the removal of the cervix which is the neck of the uterus.)Foltz and Kelsey estimated that one in five American women are without a uterus. After their paper was published, the U.S. hysterectomy rate eventually rose to one in three women. At very least, this would explain why the incidence of cervical cancer has declined in the last 50 years.
Whatever the reasons, the decline in cervical cancer deaths can hardly be described as dramatic. In 1968, there were 7,108 cervical cancer deaths in the U.S. (by 1973, nearly 50% of women reported having had one Pap test during the previous year). In 1976, there were 5,525 deaths. [In 2006, it was 3,700 deaths. For the role of the Pap test in half these deaths in 2006, see below.]
Cervical cancer is not a major cause of death in the U.S. or other Western countries, wrote Foltz and Kelsey, who pointed out that screening people for a disease of low prevalence flies in the face of the medical research standards set by leading thinkers of the time. “The lower the prevalence, the less likely it is that a positive test will correctly identify a woman who really has cancer. This means that many women with positive test results but without disease will be referred unnecessarily for further diagnostic tests and treatment, with concomitant costs and worry,” explained Foltz and Kelsey, respectively, of the Graduate School of Public Administration, New York University; and the Department of Epidemiology and Public Health, Yale School of Medicine.
Wrong Women are Getting Pap Test
Making a point that is relevant today in the promotion of Gardasil, a 1976 editorial in The New England Journal of Medicine raised the issue of whether the wrong women were being screened, “since it was the middle-class low-risk women who were coming in for Pap tests, while the low-income high-risk women were not being seen in clinics.”
If low-risk women are the major customers for the Pap test, their odds of false alarm test results will be unacceptably high, but that was never a major concern to the promoters of cervical cancer screening, chief among them, the American Cancer Society. “The accuracy and reliability of the Pap test have not been established despite its use for over 30 years,” wrote Foltz and Kelsey in 1978.
In other words, no clinical trial has ever been conducted to determine the value of the Pap test because its promotion predated the introduction of the “gold standard” of medical research. Had a large trial randomly assigned women to a Pap test or no Pap test, its efficacy and harms would have been established. And the harms are many, especially in the early days of the Pap screening, according to Foltz and Kelsey. The primary purpose of the Pap test was to detect cancer or tiny lesions that may be pre-cancerous. But by 1978, it was known that these so-called “early,” pre-cancers, carcinoma in situ detected so frequently on a Pap test do not always progress to become deadly, if left untreated.
According to Foltz and Kelsey, this was acknowledged by pathologists, but it took time for the word to get out to the surgeons (i.e., gynecologists). The unnecessary hysterectomies, oophorectomies (surgical removal of the ovaries), and biopsies for “cancers” that would have spontaneously regressed went uncounted. The focus was entirely on the decline in cervical cancer deaths.
Today, a hysterectomy following a Pap test-discovered pre-cancerous lesion or a carcinoma in situ (Latin for cancer in place) is no longer as common. But then again, who’s counting? What were cancers or precancers in another era have long since been renamed as LSIL (see the quote below) or ASCUS, which stands for atypical squamous cells of uncertain significance. The latter nicely describes the unknowns that continue to surround most of what is currently detected on a Pap test.
Today, other harms are acknowledged to result from mass Pap screening. The following quote is from the National Cancer Institute’s Web site www.cancer.gov. “Based on solid evidence, regular screening with the Pap test leads to additional diagnostic procedures (e.g., colposcopy) and treatment for low-grade squamous intraepithelial lesions (LSIL), with uncertain long-term consequences on fertility and pregnancy. These harms are greatest for younger women, who have a higher prevalence of LSIL, lesions that often regress without treatment.”
Maryann Napoli, Center for Medical Consumers© March 2007
“Half of the 9,710 U.S. women who develop cervical cancer have not had a Pap test. The other half of all cervical cancers occur in women who have had one. Imperfect testing is estimated to be responsible for 30% of all cervical cancers in women who have had Pap test and improper follow-up of abnormal test results for another 10%. Even under the best screening circumstances, an incidence rate of two to three per 100,000 women can be expected. Some risk factors for not having a Pap test are lack of insurance, poverty, geographic isolation, and lack of provider.”
From the American Cancer Society Guidelines for Human Papilloma Virus (HPV) Use to Prevent Cervical Cancer and Its Precursors reported in CA: A Journal for Clinicians, January 23, 2007.
CDC: HPV Prevalent, But Not Cancer-Causing Types
Could it be a coincidence? Just as the media was losing interest in Gardasil, the Centers for Disease Control and Prevention (federal promoters of all vaccines) published a study in the Journal of the American Medical Association entitled, “Prevalence of HPV Infection Among Females in the U.S.” (Why no study of prevalence in males?)
The short of it is this: HPV is much more common than previously thought. In fact the prevalence is highest among those aged 20 to 24 years. The overall prevalence is 26.8%, but the overall prevalence of the high-risk HPV types (i.e., potentially cancerouse) was only 2.6%. Though this study also noted previous research showing that “approximately 90% of infections clear within two years,” the new findings have already begun to play out in the media as: HPV is prevalent, get your Gardasil shots.