Reasons for cervical cancer despite extensive screening.

OBJECTIVE

To explain an age adjusted incidence rate of cervical cancer of 10.1 and 10.5 per 100,000 women, despite extensive screening.

SETTING

The Swedish county of Gävleborg in 1986 and 1987.

METHODS

Thirty eight patients with "cervical cancer" reported to the central cancer registry in Sweden were investigated. The patients and their diagnoses were scrutinised in a double blind manner.

RESULTS

Eighteen per cent (7/38) of cases were shown to be mistakes in data transfer; 11% (4/38) of cases were endocervical adenocarcinomas; 13% (5/38) were histopathological misinterpretations and should have been reported as carcinoma in situ. Of the remaining 22 patients with invasive squamous cancer, 12 (55%) had not participated in the gynaecological health control programme. Of the 10 participants with invasive squamous cancer despite this participation, eight (80%) had repeatedly had abnormal Papanicolaou smears without further gynaecological/histopathological examination and treatment. There was no evidence of cases of carcinoma in situ or endometrial cancer diagnosed in 1986-87 being squamous cervix cancer. The true incidence of squamous cervical cancer among participants was 3.0 per 100,000 for the two years scrutinised. If all the patients with Papanicolaou smear abnormalities had been properly managed at the right time, and the treatment had been successful, the incidence of invasive squamous cancer would have been 0.8 per 100,000 women among participants as opposed to 38.2 per 100,000 among non-participants.

CONCLUSION

The evidence strongly suggests overascertainment of cervical cancer, which conceals the success of screening, and also suggests that much attention must be given to clinical management of detected lesions in cervical screening. Care is needed in applying accurate histopathological criteria when making a diagnosis of invasive squamous cancer, to separate squamous cancer from other malignant tumours of the cervix, and in data transfer to cancer registries.