clinical updates

To: Health Care Provider
From: Robert J. Teears, M.D.
Boise Pathology Group, P.A.
Date: March 26, 2003

Re: ThinPrep Pap Smear Versus Conventional Pap Smear

As you may be aware, St. Luke’s Pathology Department Laboratory has been providing the ThinPrep pap test for cervical cancer screening since 1997. The ThinPrep pap test is a fluid-based method of slide preparation that was approved by the USFDA and has been shown to be significantly more effective than the conventional pap for the detection of low grade squamous intraepithelial lesions and more severe lesions in a variety of patient populations. Since approval, more than 70 studies evaluating various benefits of this technology have been published in peer-reviewed medical literature. These studies consistently demonstrate an increased detection of cervical abnormalities, a significant improvement in specimen adequacy, and viability for adjunctive testing for sexually transmitted infections.

Another recent article comparing conventional and ThinPrep paps included 1,985,350 conventional paps compared to 166,619 ThinPrep paps. The data was analyzed to eliminate the effect of any selection bias toward ThinPrep for high risk patients. Use of ThinPrep pap smears showed a greater than 100% increase in detection rate of squamous intraepithelial lesions (1.3% - 3.4%) which was statistically significant after correcting for selection bias. There was a marked improvement (233%) in detection of high grade squamous intraepithelial lesions in high risk cases and a decrease in the ASCUS to SIL ratio from 3.1 to 1.5. There was also a significant decrease in the false negative proportion (57%). (Archives of Pathology & Laboratory Medicine. Volume 127, page 200-204, February, 2003.)

Another advantage of the ThinPrep pap test is its approval by the FDA for "reflex" HPV DNA testing directly from the initial specimen vial using the Digene Hybrid Capture II Assay. We believe this feature has taken on particular significance with the publication of the new "2001 Consensus Guidelines for the Management of Women with Cervical Cytological Abnormalities and Cervical Cancer Precursors," published in the April 24, 2002, issue of the Journal of the American Medical Association (JAMA). A panel of 121 medical experts in the field of cervical cancer screening and management, representing 29 leading medical organizations, developed these guidelines. Regarding the issue of various approaches for managing borderline pap results called ASCUS (atypical squamous cells of undetermined significance), the 2001 Consensus Guidelines state: "Reflex" Human Papilloma Virus (HPV) DNA testing is the "preferred approach" for managing patients with borderline pap results. The guidelines observed, "Reflex HPV DNA testing offers significant advantages since women do not need an additional clinical examination for specimen collection, and 40% to 60% of women will be spared a colposcopic examination. Moreover, women testing negative for HPV DNA can rapidly be assured that they do not have a significant lesion."

We believe that this is a very clear message and a strong endorsement of this method of managing patients with borderline cytology results. The publication of the 2001 Consensus Guidelines, together with the weight of scientific evidence and our own experience of the clinical advantages of the ThinPrep pap test, leads us to strongly urge clinicians to consider complete conversion to the liquid-based ThinPrep method from the conventional method of cervical cancer screening.

We will continue to accept conventional pap smears at our laboratory when requested. However, we believe that it is in the best interest of our health providers, their patients, and our laboratory to provide a single, standardized approach to cervical cancer screening encompassing the latest technology in liquid-based screening.

We urge you to refer to your own specialty literature, colleagues, and residency training programs regarding the efficacy of the ThinPrep method for the detection of cervical squamous intraepithelial lesions. All necessary collection supplies, including slides, requisition forms, cervical brooms, brushes, spatulas and vials of the ThinPrep solution are provided at no charge as is a short instruction video tape on proper method of sample collection for the ThinPrep pap smear.

Thank you for taking the time to review this information. We greatly appreciate your loyalty to Boise Pathology Group at St. Luke’s Hospital and look forward to continuing to provide you with the highest quality laboratory services.

If you have any questions regarding this information, please feel free to contact any one of us at 381-2378 or 381-2367.