Risk : How does it define cervical cancer screening?

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Marcia Stafford
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1 Risk : How does it define cervical cancer screening? Alan G. Waxman, MD, MPH Dept. of Obstetrics and Gynecology University of New Mexico The University of New Mexico

2 Disclosures I have no commercial interests to disclose. Photos: George Papanicolaou NIH Monkeys and Apes are mine

3 Educational Objectives Review screening intervals historically and basis for current recommendations. List three different risk levels used in setting the threshold for colposcopy. Discuss the inconsistencies in our understanding of acceptable risk in cervical cancer screening.

4 Finding Balance in Cervical Screening agw We use imperfect tests for screening and diagnosis. False positive results lead to unnecessary colposcopy and treatment with possible adverse consequences. False negative tests can result in cancers developing in the interval between screening. How much risk are we willing to accept and how do we define risk?

5 The public health perspective of risk focuses on benefits and risks for the overall population. How many precancers and cancers will develop in a population despite screening at a given interval? Can we as a society accept these numbers? How many unnecessary colposcopies and treatments are we willing to accept to prevent one cancer? agw

6 The individual woman and her provider want a simpler estimation of risk. What are my chances of getting cancer before my next screening? What are my chances of getting a treatment I didn t need? agw

7 How often should women get a Pap Test? Papanicolaou 1928: Papanicolaou -cervical cytology 1943: Papanicolaou and Traut publish monograph 1957: ACS Uterine Cancer Year promotes annual Pap 1960: Birth Control Pill Between the 1980 and 2012, U.S. guidelines changed 7 times.

8 Current U.S. Guidelines: ACS/ ASCCP/ ASCP, ACOG, USPSTF Start screening at age 21 with cytology every 3 years. From age 30 65, co-testing every 5 years is recommended. If HPV not available, continue with cytology alone every 3 years. Primary HPV screening after age 25 using FDA approved test is also acceptable. Saslow et al J Low Genit Tract Dis. 2012; 16(3)

9 Does a negative cytology every 3 years or a negative HPV test every 5 years offer a risk that s acceptable? Joint European Cohort Study compared HPV testing with conventional Pap in 6 countries N=24,295 Rate of CIN 3+ after baseline negative test 3 yrs 4 yrs 5yrs 6yrs Pap 0.51% 0.69% 0.83% 0.97% HPV- 0.12% 0.19% 0.25% 0.27% Dillner, J. et al. BMJ 2008;337:a1754

10 Does a negative cytology every 3 years or a negative HPV test every 5 years offer a risk that s acceptable? 1.4 million women followed with cotesting since 2007 Kaiser Permanente Northern California (KPNC) Pap negative at baseline 5 year Risk of CIN % Pap and HPV both negative at baseline 5 year Risk of CIN % Katki et al J Lower Genital Tract Dis 2013;17(5):S28-35

11 So a woman with a negative cotest screened every 5 years can be reassured that her risk of getting CIN 3 or worse before her next screening is only 8 out of 10,000. That seems like a reasonable risk to take. AGW

12 Recently a Minority Viewpoint suggested that the risk of cancer with cotesting every 5 years is too high. Changing cotesting interval from q 3 years to q 5 years 2.71 additional cancers / 1,000 women (1 in 369) 0.61 additional deaths / 1,000 women (1 in 1,639) Assuming 72 million women aged in U.S. 195,000 additional cancers over lifetime 44,000 additional deaths over lifetime Kinney et.al. Obstet Gynecol (2);

13 agw Calculating number of deaths on a population level puts risk in a different perspective!

14 With the strategy of equal management for equal risk it s important to know what the risk is for different screening results. AGW

15 For example, if a woman has LSIL on her Pap, what s the chance she will have CIN 3 or cancer in the near future? AGW

16 In the ALTS trial, the 2 year cumulative risk of CIN 3+ for a cytology result of LSIL was 10 % HSIL LSIL ASC-US HPV+/ASC-US 10% Castle. Am J Obstet Gynecol October; 197(4): 356

17 By convention, we set that level of risk as the threshold for colposcopy. HSIL LSIL ASC-US HPV+/ASC-US Colposcopy Observe 10% Castle. Am J Obstet Gynecol October; 197(4): 356

18 Did we choose the threshold for colposcopy because 10% represented a high enough risk? Or because LSIL seemed a risky enough Pap? HSIL LSIL ASC-US HPV+/ASC-US Colposcopy Observe 10% Castle. Am J Obstet Gynecol October; 197(4): 356

19 In the KPNC study, the 5 year cumulative risk of CIN 3+ for a cytology result of LSIL was only 5.2 %. Our patients understanding of What is my risk? becomes blurred. HSIL LSIL ASC-US HPV+/ASC-US Colposcopy Observe 5.2% Castle. Am J Obstet Gynecol October; 197(4): 356

20 Our patient with LSIL might well be confused. Is her risk 10% in 2 years (Undoubtedly higher over 5 years) Or is it 5.2% over 5 years? agw

21 Some have criticized the ASCCP Guidelines as being based on data that is specific to a population that may not be typical of the U.S. as a whole. The population make up of N. California Kaiser subscribers is different from the state-wide registry of New Mexico, yet the determination of risk is quite similar as is the rank order of diagnoses. 5 year cumulative risk of CIN 3+ in two different U.S. populations Cytology NM HPV Pap registry KPNC HSIL LSIL ASC-US ASC-US / HPV ASC-US / HPV Cytol negative Gage J. Obstet Gynecol. 2016;128 :

What level of risk is acceptable? Can we set the colposcopy threshold based on a numeric level of risk or should we base it on a consensus agreement that LSIL cytology is too risky to watch? Is.

22 What level of risk is acceptable? Can we set the colposcopy threshold based on a numeric level of risk or should we base it on a consensus agreement that LSIL cytology is too risky to watch? Is.08% risk of CIN 3+ at a 5 year screening interval a safe threshold on which to base our screening interval? Should we abandon CIN 3+ as an untenable surrogate endpoint for our studies and require instead the considerable rarer endpoint of cancer? agw

23 These are questions without easy answers that challenge us as we develop guidelines and counsel our patients. Thank you. agw

October 9, Dear Ms. Chowdhury:

October 9, Dear Ms. Chowdhury: October 9, 2017 Joya Chowdhury, MPH Senior Coordinator, USPSTF Department of Health and Human Services Agency for Healthcare Research and Quality Center for Evidence and Practice Improvement Room 06E65A