CANCER-DIAGNOSIS AFTER A REPORT OF NEGATIVE CERVICAL CYTOLOGY

Objectives: 1. To determine the annual rate of interval squamous cance r of the cervix after a negative Papanicolaou smear report. 2. To eval uate the proportion of women with cervical cancer who received negativ e cervical smear reports during the three years before the cancer diag nosis.Design and setting: Objective 1. A prospective study of the inci dence of squamous cervical cancer from 1990 to 1993 among women who re ceived negative cervical smear results in Victoria in 1990. Objective 2. A retrospective audit of preceding cervical smear results from 1990 to 1993 in women diagnosed with cervical cancer in Victoria in 1993. Results: The average interval cervical cancer rate was 2.54 squamous c ancers per 100 000 women per year (95% confidence interval, 1.75-3.67) during the first three years after a negative smear report. The inter val cancer rate did not vary by age group nor by the endocervical stat us of the negative smear report. Of the 233 cases of cervical cancer d iagnosed during 1993, 56 women (24%) had negative cervical cytology re ported during the preceding three years. The frequency of preceding ne gative cervical cytology was greater for non-squamous cancer (22 women [33%] from 66 cases) than for squamous cancer (34 women [20%] from 16 7 cases). Conclusion: The rate of interval cancer diagnosis is very lo w compared with expected rates in the absence of screening, indicating the effectiveness of the cervical screening program in Victoria.