Morphogenesis of cervical cancer.Findings from San Diego County Cytology Registry

The San Diego Cytology Registry collected results on cytology examinations on more than 180,000 women; more than 60,000 of these had multiple examinations. The age-specific prevalence and incidence rates for suspicious and positive cytology and for dysplasia, carcinoma in situ and invasive cancer of the cervix are presented. These are analyzed in terms of the morphogenesis of cervical cancer. Carcinoma in situ reaches its maximum incidence rate among women aged 25 to 29. The rates then decrease and continue at a low level after age 35. This peak of incidence at an early age has implications as to the pathogenesis of cervical cancer. Incidence rates for dysplasia also rise rapidly and at an earlier age than carcinoma in situ. Dysplasia remains at a high incidence over a longer age span than carcinoma in situ but decreases precipitously after age 40. Dysplasia and carcinoma in situ together would exceed the needs for invasive cervical cancer and some would need to terminate by regression. The prevalence rates for dysplasia and carcinoma in situ are several times greater than their respective incidence rates. Estimates of average duration for each are 3.8 years of dysplasia and 8.1 years of carcinoma in situ. Not all new disease developing from a population that has been repeatedly negative cytologically is found in a carcinoma in situ stage. The authors conclude that 10 to 15% of carcinomas of the cervix become invasive early in their development.