Preliminary Findings of the Memphis-Shelby County Uterine Cancer Study and Their Interpretation

Abstract

The use of prevalence and incidence rates for determining average duration of the prevalence period is briefly described. Preliminary data covering the period 1952-1955 are presented on carcinomas in situ and invasive cancers of the cervic found by means of vaginal cytology in 1st examination of 82,957 women living in Memphis and Shelby County, Tennessee; and the annual rescreening findings in 26,005 women examined a 2d time, and 6702 examined a 3d time. Calculations from age-specific incidence and prevalence rates indicate that invasive cervical cancer has an average duration of 3 to 4 years from the beginning of stromal invasion to symptomatic, clinically suspect, cancer. The data are less adequate for estimating the duration of carcinoma in situ. If the assumption is made that the latter is invariably the precursor of invasive cervical cancer the estimated average duration is 4 to 5 years. Crude estimates without this assumption provided an estimate for white women in this same range; for Negro women somewhat less. A significant proportion of women who develop cervical cancer appear to progress from negative cytology to positive cytology associated with an early invasive cancer of the cervix in 1 year.