Medicolegal affairs. International Academy of Cytology Task Force summary. Diagnostic Cytology Towards the 21st Century: An International Expert Conference and Tutorial

Modeling Cervical Cancer Screening Strategies With Varying Levels of Human Papillomavirus Vaccination

IMPORTANCE

Cervical cancer screening is a lifesaving intervention, with an array of approaches, including liquid-based cytology (LBC), molecular testing for human papillomavirus (HPV) infection, and combinations via parallel cotesting or sequential triage. Maximizing screening efficacy while minimizing overtreatment is vital, especially when considering how the HPV vaccine will affect the interpretation of results.

OBJECTIVES

To estimate the likely outcomes of different screening modalities and to model how the increasing uptake of the HPV vaccine could affect the interpretation of screening results.

DESIGN, SETTING, AND PARTICIPANTS

This decision analytic model established a simple Markov model to compare the outcomes of different cervical cancer screening modalities on a simulated population of women (aged ≥25 years), considering different levels of HPV vaccination.

MAIN OUTCOMES AND MEASURES

The number of cases of cervical intraepithelial neoplasia (CIN) grade 2 and 3 detected and missed, the number of false positives, and the number of tests required to achieve a given level of accuracy. Positive and negative predictive values of different modalities were simulated under varying levels of HPV vaccination and therefore HPV prevalence.

RESULTS

In a simulated population of 1000 women aged 25 years and older with an HPV prevalence of 2%, HPV-based modalities outperformed LBC-based approaches, detecting 19% more true positives (HPV test sensitivity, 89.9% [95% CI, 88.6%-91.1%]; LBC test sensitivity, 75.5% [95% CI, 66.6%-82.7%]). While cotesting markedly reduced missed cases, detecting 29% more true positives than LBC alone (19.5 [95% CI, 19.3-19.7] per 1000 women screened vs 15.1 [95% CI, 13.3-16.5] per 1000 women screened), it unacceptably increased excess colposcopy referral by 94% (184.4 [95% CI, 181.8-188.0] false positives per 1000 women screened vs 95.1 [95% CI, 93.1-97.0] false positives per 1000 women screened). By contrast, triage testing with reflex screening substantially reduced false positives by a factor of approximately 10 (eg, HPV with LBC triage, 9.6 [95% CI, 9.3-10.0] per 1000 women screened). Over a lifetime of screening, reflex approaches with appropriate test intervals maximized therapeutic efficacy; as HPV vaccination rates increased, HPV-based screening approaches resulted in fewer unnecessary colposcopies than LBC approaches (HPV testing, 80% vaccine coverage: 44.1 [95% CI, 40-45.9] excess colposcopies; LBC testing, 80% vaccine coverage: 96.9 [95% CI, 96.8-97.0] excess colposcopies).

CONCLUSIONS AND RELEVANCE

In this decision analytic model, the effectiveness of cervical cancer screening was dependent on the prevalence of cervical dysplasia and/or HPV infection or vaccination in a population as well as the sensitivity and specificity of various modalities. Although screening is lifesaving, overtesting or modalities inappropriate to the target population may cause significant harm, including overtreatment.

Is an indistinct picture "exactly what we need"? Objectivity, accuracy, and harm in imaging for cancer

Assumptions about the epistemic ideal of objectivity, closely related to ontological assumptions about the nature of disease as pathophysiological abnormality, lead us into oversimplified ways of thinking about medical imaging. This is illustrated by current controversies in the early detection of cancer. Improvements in the technical quality of imaging failed to address the problem of overdiagnosis in breast cancer screening and exacerbate the problem in thyroid cancer diagnosis. Drawing on Douglas and on Daston and Galison, I distinguish 3 dimensions of objectivity (accuracy, reliability, and precision) and demonstrate ways they may be at odds, as illustrated in the early detection of cancer. Guidelines for evaluating the efficacy of diagnostic imaging are insufficiently sensitive to this complexity. Improving imaging quality may raise epistemic issues, place disease definitions in question, and lead to overall harm or to changes in the distribution of harms and benefits among population subgroups. With a nod to Wittgenstein, I argue that we cannot take for granted that "an indistinct picture" is not "exactly what we need."

Assessment of the Validity and Reproducibility of the Pap Smear in Mexico: Necessity of a Paradigm Shift

BACKGROUND AND AIMS

An assessment was performed of the quality of Pap readings in 19 cytology laboratories (CLs) in Mexico from the Cervical Cancer Screening Program.

METHODS

Nine CLs were affiliated with the Health Ministry (SSA), and ten were affiliated with the Mexican Social Security Institute (IMSS). Two sets of 200 cervical cytology specimens were prepared, one set for each institution. Fourteen percent of the specimens were positive and six were inappropriate for diagnosis (3%). All cervical cytology specimens were processed in the cytopathology laboratory at the General Hospital of Mexico, and histopathology was available for each positive case.

RESULTS

Thirty percent of the SSA reading centers had a sensitivity of at least 80%; however, not one of the ten IMSS laboratories evaluated reached this figure. Some reading centers had a sensitivity <65%, meaning that nearly half of the specimens with a cytology consistent with cervical neoplasm were not identified.

DISCUSSION

Given these results, it is a priority to effect a paradigm shift combining various screening tests to improve adherence to standards and enhanced cost-effectiveness of the early detection of cervicouterine cancer (CC) in Mexico.

Is it necessary to repeat cervical cytology at the tie of a colposcopy?

OBJECTIVES: to evaluate whether repeating Papanicolaou smear testing at the time of colposcopy improves agreement between cytology and histopathology in the diagnosis of cervical cancer. METHODS: this cross-sectional study included 397 women referred for colposcopic evaluation following an abnormal cervical smear test. The cytology was repeated at the time of the colposcopy using a conventional medium. The two cytology tests were compared with each other and with the histopathological findings obtained by colposcopy-directed biopsy. The 2001 Bethesda system and the WHO 1994 classification were used for reporting cytology and histology results. The kappa coefficient was used to determine the agreement between methods. RESULTS: the comparison between the initial cytology findings and cytology performed at the time of colposcopy revealed a kappa of 0.297 (95%CI: 0.235-0.359), indicating a fair degree of agreement. When the results of the initial cytology were compared with histopathology, a kappa of 0.261, considered to represent a fair degree of agreement, was obtained (95%CI: 0.181-0.340). A kappa of 0.408, considered to represent moderate agreement, was found when the second cytology findings were compared with the histopathology (95%CI: 0.332-0.485). CONCLUSIONS: the agreement between cytology and histology improved when cytology was repeated at the time of colposcopy, following an initial abnormal test.

Living with uncertainty: equivocal Pap test results and the evolution of ASC terminology

Communication of equivocal findings and their significance has been a significant challenge related to Pap testing throughout its history. Terminology to report these findings has changed considerably to accommodate the changes in understanding of cervical neoplasia, and to accommodate new management strategies, tests, and technologies. This article reviews the evolution of terminology for equivocal Pap test findings from the original Papanicolaou classification to the current the Bethesda System 2001 atypical squamous cells terminology, the implication and use of these terms, and the changing landscape of cervical neoplasia screening, which prompted these terminology changes. Emerging issues related to improving risk stratification through the introduction of additional terms and the impact of human papillomavirus testing may alter terminology of equivocal findings in the future.

Error reduction and risk management in cytopathology

Currently, tort reform is not a major priority in either the Congress of the United States or in state legislatures. Thus, it is fortunate that medical negligence claims against pathologists are relatively infrequent, at 8.3% per year per 100 insured pathologists (data from the Doctors' Company, 2000-2003). However, claims for "missed" cervical cytology specimens rank third, behind those for alleged misinterpretation of breast biopsies and pigmented skin lesions. The severity of cervical cytology errors is high, at almost $700,000 per claim, surpassed only by those concerning melanoma. There are common threads that appear consistently in the analysis of slides from allegedly misdiagnosed cervical cytology cases, including small-cell variants of high-grade squamous intraepithelial neoplasia (HGSIL), present in small numbers; hyperchromatic crowded cell groups; atypical squamous cells of undetermined significance (ASCUS); smears taken during menses; other bloody smears, particularly with degenerative features or excessive inflammation; others showing atypical repair; and unsatisfactory samples. It is important for pathologists to spend time with cytotechnologists to emphasize the patterns of abnormal smears at low microscopic magnification and those backgrounds featuring blood and inflammation which require particular attention. Managing the "look-back" requirement of the Clinical Laboratory Amendments of 1988 (CLIA88) is also crucial; the need to issue amended reports as a consequence of that provision is quite rare. Procedures for administrating and reporting retrospective reviews under the CLIA88 should be clearly outlined in a peer-reviewed procedure document in each laboratory. They should be reviewed and approved by risk managers or insurance carriers, and documented in such a manner that one obtains maximal protection from legal discovery. Consumer education is particularly important in maintaining laboratory performance and reducing risk from error in cytology. Periodic feedback to clinicians on the quality of their smear preparations, the use of ancillary techniques (eg, human papillomavirus testing), and discussion of reporting terminology are important. Moreover, one should stress the need for pertinent clinical history that is often required to initiate quality control measures for evaluation and reporting of cervical cytology specimens. The incidence of cervical cancer in the United States, at only 9700 new cases per year, is low, emphasizing the need for clinical vigilance, attention to unexplained symptoms and signs, and biopsies of any cervical abnormality. These and other efforts may assist in reducing the risk of litigation attached to allegedly false-negative gynecologic and nongynecologic cytology samples.

Results of multiple-slide, blinded review of Papanicolaou slides in the context of litigation. Determining what can be detected regularly and reliably

BACKGROUND

Multiple-slide, blinded review has been endorsed by several cytology and pathology organizations as the most appropriate method for the review of cervicovaginal specimens in the context of litigation. This process involves review of litigation slides in a blinded manner by multiple independent cytotechnologists and the comparison of those results with those of validation cases that are comprised of known abnormalities with biopsy follow-up. To the authors' knowledge, the results of this method have not been previously published.

METHODS

The results of the blinded review program at the Center for Cytopathology and Molecular Research at the Medical University of South Carolina for the years 1998-2004 were reviewed.

RESULTS

A total of 135 litigation slides and 122 validation slides were reviewed. The interpretations of these cases were found to be significantly different (P < 0.001). Litigation cases were significantly more likely to be interpreted as either negative for intraepithelial lesion (NIL) or atypical squamous cells/atypical glandular cells (ASC/AGC) (P < 0.001). The results appeared to be independent of the individual cytotechnologists involved. Approximately 10% of litigation cases were called at least ASC/AGC by all observers and 4% were interpreted as NIL by all observers. For litigation cases, ASC/AGC was found to be just as reproducible as high-grade squamous intraepithelial lesion. The results demonstrated that only 10% of litigation cases are regularly and reliably identified as abnormal, whereas a single review as performed by an expert cytologist can be expected to classify 56% of cases as abnormal.

CONCLUSIONS

This program suggests that a majority of litigation cases are not regularly and reliably identified as abnormal, and a single review will routinely overestimate the percentage of cases that are identified regularly and reliably.

Cytopathology proficiency testing: Where do we go from here?

With the recent introduction of nationwide proficiency testing in cytopathology (PTC), reconsideration of several aspects of this controversial quality assurance method becomes justified. This paper discusses various merits and demerits of the PTC system currently prescribed by federal regulations, points out perceived deficiencies, and suggests methods for improvement.

Cytologic diagnosis: expression of probability by clinical pathologists

BACKGROUND

Clinical pathologists use descriptive terms or modifiers to express the probability or likelihood of a cytologic diagnosis. Words are imprecise in meaning, however, and may be used and interpreted differently by pathologists and clinicians.

OBJECTIVES

The goals of this study were to 1) assess the frequency of use of 18 modifiers, 2) determine the probability of a positive diagnosis implied by the modifiers, 3) identify preferred modifiers for different levels of probability, 4) ascertain the importance of factors that affect expression of diagnostic certainty, and 5) evaluate differences based on gender, employment, and experience.

METHODS

We surveyed 202 clinical pathologists who were board-certified by the American College of Veterinary Pathologists (Clinical Pathology). Surveys were distributed in October 2001 and returned by e-mail, fax, or surface mail over a 2-month period. Results were analyzed by parametric and nonparametric tests.

RESULTS

Survey response rate was 47.5% (n = 96) and primarily included clinical pathologists at veterinary schools (n = 58) and diagnostic laboratories (n = 31). Eleven of 18 terms were used "often" or "sometimes" by >/= 50% of respondents. Broad variability was found in the probability assigned to each term, especially those with median values of 75 to 90%. Preferred modifiers for 7 numerical probabilities ranging from 0 to 100% included 68 unique terms; however, a set of 10 terms was used by >/= 50% of respondents. Cellularity and quality of the sample, experience of the pathologist, and implications of the diagnosis were the most important factors affecting the expression of probability.

CONCLUSION

Because of wide discrepancy in the implied likelihood of a diagnosis using words, defined terminology and controlled vocabulary may be useful in improving communication and the quality of data in cytology reporting.

Outcomes of screening to prevent cancer: analysis of cumulative incidence of cervical abnormality and modelling of cases and deaths prevented

OBJECTIVE

To determine the frequency of different outcomes in women participating in cervical screening.

DESIGN

Analysis of screening records from 348 419 women, and modelling of cases of cervical cancer and deaths with and without screening.

SETTING

Cervical screening programme in Bristol.

RESULTS

For every 10 000 women screened from 1976 to 1996, 1564 had abnormal cytology, 818 were investigated, and 543 had abnormal histology. One hundred and seventy six had persistent abnormality for two years or more. In the absence of screening 80 women would be expected to develop cancer of the cervix by 2011, of whom 25 would die. With screening 10 of these deaths would be avoided. Comparison of cumulative abnormality rates with numbers expected to develop cancer in the absence of screening suggests that at least 80% of high grade dyskaryosis and of high grade dysplasia would not progress to cancer. The lifetime risk of having abnormal cytology detected could be as high as 40% for women born since 1960.

CONCLUSIONS

Screening is labour and resource intensive. It involves treatment for many women not destined to develop invasive cancer. The increased intervention rate for cervical abnormality in England is due to change in practice, not a cohort effect, and is probably the reason for the marked fall in incidence and mortality during the 1990s. For other cancers there is scope for major iatrogenic harm from screening because of invasive tests and treatments.

Litigation cells: their incidence and classification in gynecologic smears

"Litigation cells" are defined as benign cells which may mimic dysplasia or cancer and might be used by plaintiffs' witnesses to imply that the cytotechnologist or pathologist "missed" cells of dysplasia or cancer. We reviewed 180 cervical smears from 166 patients who had hysterectomy for benign leiomyomas. All smears were performed within 12 months prior to hysterectomy. None of the uteri contained dysplasia or cancer on histologic examination. 90.6% of smears reviewed had at least one cell or cell group with atypia mimicking dysplasia or cancer. These "litigation cells" were classified as follows: parabasal cells, metaplastic squamous cells, degenerated endocervical cells, reactive endocervical cells, endometrial cells, neutrophils, histiocytes, and air-dried cells. Diseases mimicked by these cells included squamous cell carcinoma, high-grade squamous intraepithelial lesion, low-grade squamous intraepithelial lesion, adenocarcinoma, and glandular dysplasia. These "litigation cells" can be correctly classified by experienced cytotechnologists and cytopathologists and recognized as benign. We recommend that in all cases of alleged malpractice against cytotechnologists and/or pathologists the smears should be reviewed by a panel of individuals trained and experienced in cytopathology. The smears should be reviewed without knowledge of the clinical outcome and in an environment that simulates the normal screening practice.

Estimating the percentage of Papanicolaou smears that can be reproducibly identified: modeling Papanicolaou smear interpretation based on multiple blinded rescreenings

BACKGROUND

Multiple blinded rescreenings of Papanicolaou (Pap) smears for litigation purposes is based on the assumption that a subset of Pap smears can be reproducibly identified. The size of this subset is not known.

METHODS

To estimate the size of the subset of Pap smears that can be reproducibly identified, a model was constructed based on the results of repeated blinded screenings in the AutoPap Primary Screening System Trial. Additional analysis came from data in the literature.

RESULTS

Routine and AutoPap-assisted screening both have a detection rate for all detected abnormal cases of < 50%. Models with only two subsets or types of slides each with a different detection rate correlated well with the available data. Data from multiple rapid reviews strongly supported the existence of additional definable subsets. Although the percentage of cases with an expected detection rate of 100% in a three-subset model might have been as high as 30% of the abnormal cases detected in a single review, all estimates that included a second subset of slides with at least a 50% detection rate limited the percentage of slides in the 100% sensitive subset of slides to < 2% of all abnormal slides and < 6% of all abnormal slides detected by a single screening.

CONCLUSIONS

Repeated screenings of Pap smears allowed more accurate models of the sensitivity of Pap-smear screening and the overall incidence of abnormal cases. The data strongly supported the existence of multiple subsets of Pap smears, which can be defined by repeated blinded rescreenings. The percentage of slides that can be reproducibly identified was small.

Pathologists and the judicial process: how to avoid it

This review article covers the full range of issues concerning malpractice as it relates to pathologists. Following a brief summary as to the incidence and general statistics on the outcome of lawsuits as well as common pathology misdiagnoses resulting in lawsuits, the definition of malpractice is discussed. These include duty, breech of standard of care, proximal cause, and damage. Details are provided as to what a pathologist should do from the initial threat of a lawsuit, to the initial lawsuit, and through the initial physician/lawyer meeting. An in-depth analysis as to how pathologists should handle themselves through the discovery process and, in particular, deposition is provided. Plaintiff attorneys' goals at deposition are covered in depth. These goals include: 1) education about the pathologist's case and strategies; 2) impeachment of the pathologist's credibility; and 3) judgment as to how effective a witness the pathologist will be at trial. Various types of plaintiff's attorney at deposition are summarized. Also discussed is the post-deposition meeting with the legal representative, whether to settle, and specific issues relating to trial. Finally, general tips on how to avoid a lawsuit in pathology are reviewed.

Perceived sensitivity of mammographic screening: women's views on test accuracy and financial compensation for missed cancers

OBJECTIVES

To estimate women's expectations of the accuracy of screening mammography and to explore attitudes towards compensation for missed cancers.

DESIGN

Cross sectional survey (by telephone).

SETTING

Australia; population-based survey conducted in April 1996.

PARTICIPANTS

Random sample of women aged 30-69 years. A total of 2935 women completed the Breast Health Survey (adjusted response rate 65%). A random sample of 115 completed this sub-survey on perceived sensitivity of mammographic screening and compensation for missed cancers.

RESULTS

About one third of women (32.2%, 95% CI 23.7, 40.7) had an unrealistically high expectation of the sensitivity of screening mammography, reporting it to be 95% or higher. Approximately 40% of the women (43.5%, 95% CI 34.4, 52.6) thought that screening mammography should pick up all cancers (should have a sensitivity of 100%). Just under half the women (45.2%, 95% CI 36.1, 54.3) said financial compensation should be awarded for a cancer missed by screening mammography even if the cancer was missed as a consequence of the small failure rate of the test. Younger women living in metropolitan areas and women who had realistic expectations of the accuracy of the tests were more likely to favour financial compensation.

CONCLUSION

Unrealistically high expectations of the sensitivity of screening mammography were common in this group of women. Many women favoured financial compensation for missed cancers even if the cancer was missed solely because of the failure rate of the test. Public education is required to inform women of the limited sensitivity of breast cancer tests but this may not reduce claims for financial compensation when cancers are missed.