Correspondence

Extending the Interval between Cervical-Cancer Screenings

N Engl J Med 2004; 350:414-415January 22, 2004

Article

To the Editor:

Although the conclusion of the article by Sawaya et al. on the interval between cervical-cancer screenings (Oct. 16 issue)1 may be correct, they failed to note one of the large biases. They presumed the same sensitivity and specificity for colposcopy whether the abnormal Papanicolaou test had been preceded by one or more years without a Papanicolaou test. A finding of grade 2 or grade 3 cervical intraepithelial neoplasia on colposcopic biopsy in a patient who has not had a Papanicolaou test for three years is more likely to be an invasive cancer on cold-knife conization than is the case for a patient who had a normal result or even an abnormal result on a Papanicolaou test the previous year.

Peter W. Rufleth, M.D.
6 Main St., Hyannis, MA 02601
prufleth@hotmail.com

1 References

1. 1

   Sawaya GF, McConnell KJ, Kulasingam SL, et al. Risk of cervical cancer associated with extending the interval between cervical-cancer screenings. N Engl J Med 2003;349:1501-1509
   Full Text | Web of Science | Medline

Author/Editor Response

It is possible that some women with at least three prior normal tests and high-grade cervical intraepithelial neoplasia were ultimately given a diagnosis of cancer on the basis of conization; this likelihood may increase as the time between the previous normal test and the abnormal test prompting colposcopy increases. In our study, this interval ranged from 9 to 36 months. Since only 16 of 32,320 women were in this diagnostic category, the number of potentially missed cancers would be small; invasive cancer is rare in women with normal results on recent screening tests1,2 and is uncommonly diagnosed at the time of conization.3,4

In This Week in the Journal5 our article is described as concluding that “screening performed once every three years is associated with an excess risk of cervical cancer of no more than 3 in 100,000.” This statement requires clarification. “Every three years” implies a lifetime screening periodicity; we reported only the estimated excess risk associated with extending the screening interval for a single three-year period (which we estimated at 3 in 100,000). Lifetime screening every three years, as compared with every year, can be expected to have excess-risk estimates greater than 3 per 100,000. Projecting outcomes further in the future, however, requires accounting for competing causes of mortality and diminishing differences in risk that we noted between screening strategies as women age. The next steps in formulating rational health care policies include performing cost-effectiveness and cost–utility analyses to identify screening strategies that maximize benefits and minimize costs and harm.

George F. Sawaya, M.D.
University of California, San Francisco, San Francisco, CA 94118

Shalini Kulasingam, Ph.D.
Duke University, Durham, NC 27710

Herschel Lawson, M.D.
Centers for Disease Control and Prevention, Atlanta, GA 30341

5 References

1. 1

   Janerich DT, Hadjimichael O, Schwartz PE, et al. The screening histories of women with invasive cervical cancer, Connecticut. Am J Public Health 1995;85:791-794
   CrossRef | Web of Science | Medline

2. 2

   Sung HY, Kearney KA, Miller M, Kinney W, Sawaya GF, Hiatt RA. Papanicolaou smear history and diagnosis of invasive cervical carcinoma among members of a large prepaid health plan. Cancer 2000;88:2283-2289
   CrossRef | Web of Science | Medline

3. 3

   Andersen ES, Nielsen K, Pedersen B. The reliability of preconization diagnostic evaluation in patients with cervical intraepithelial neoplasia and microinvasive carcinoma. Gynecol Oncol 1995;59:143-147
   CrossRef | Web of Science | Medline

4. 4

   Costa S, Nuzzo MD, Rubino A, et al. Independent determinants of inaccuracy of colposcopically directed punch biopsy of the cervix. Gynecol Oncol 2003;90:57-63
   CrossRef | Web of Science | Medline

5. 5

   This week in the Journal. N Engl J Med 2003;349:1493-1493
   Full Text