Recent negative cytology prior to histologically confirmed carcinoma in situ of the cervix.

Women with histologically confirmed carcinoma in situ of the cervix were studied within the records of the Victorian Cervical Cytology Registry. The prevalence of histologically confirmed carcinoma in situ during 1992 was 2.67 per 1,000 women screened. Thirty per cent (401 of 1,327) of the women with carcinoma in situ had negative cervical cytology reported during the 2 years prior to the diagnosis of carcinoma in situ and at least 49% (648 of 1,327) had negative cytology during the preceding 5 years. Adenocarcinoma in situ comprised 3.4% of all cases; these women were significantly older and more likely to have had a recent negative smear report than women with squamous carcinoma in situ. Fifty-five per cent of the women with squamous carcinoma in situ had HPV reported on the biopsy compared with only 27% of the women with adenocarcinoma in situ. Ten per cent of the women with carcinoma in situ had a past history of cytological or histological abnormality; this proportion did not vary by type of carcinoma in situ. This relatively high proportion of negative cytology in close proximity to a diagnosis of carcinoma in situ is to be expected if there is active treatment of lesser lesions and frequent screening of members of the community.