Misclassification of microinvasive cervical cancer and carcinoma-in-situ of the cervix

Abstract

Kavanagh AM, Brown R, Fortune D, Mulvany N, Scurry J, Giles GG. Misclassification of microinvasive cervical cancer and cardnoma- in-situ of the cervix. Int J Gynecol Cancer 1998; 8: 46-50. We estimated the extent of misclassification of microinvasive cervical cancer and carcinoma-in-situ by reviewing the histology of all cases of squamous cell micro invasive disease (N = 61) and a random sample of cases of squamous cell carcinoma-in-situ (N = 35) reported to the Victorian Cancer Registry in 1992. Five cases (3 microinvasive and 2 cardnoma- in-situ) were excluded for technical reasons or because we were unable to obtain the slides for review. Four pathologists reviewed the slides and came to a consensus diagnosis. Eleven cases (19.0%, 95% CI 8.9-29.1) of squamous cell microinvasive cancer had squamous cell carcinoma- in-situ on review and three cases (5.2%, 95% CI 0.0-10.9) were invasive cancer. Two cases (6.1%, 95% CI 0.0-14.1) of carcinoma-in-situ had microinvasive disease on review. Adjusting squamous cell cervical cancer incidence rates for overcalling of squamous cell carcinoma-in-situ as squamous cell microinvasive cancer results in a 5.7% reduction in the age-standardized incidence rate of squamous cell cervical cancer; however, adjusting for both the overcalling of squamous cell carcinoma-insitu and the undercalling of squamous cell microinvasive cancer as squamous cell carcinoma-in-situ results in a 49% increase in the agestandardized incidence rates of squamous cell cervical cancer. Errors in cervical cancer incidence rates hinder the evaluation of cervical cancer screening programs.