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The accuracy of cervicovaginal cytology following radiotherapy for cervical cancer is compromised by the anatomical and tissue changes resulting from irradiation. Collection of representative samples may be more difficult, and benign radiation changes, post‐irradiation dysplasia, and the frequent occurrence of repair cells and active stromal cells in post‐irradiation smears may cause diagnostic problems. Nevertheless, cytology is a valuable tool for the detection of locally recurrent cervical cancer. It is simple and economical to perform at the time of clinical follow‐up examination, and may detect occult tumour recurrence. Awareness of the cellular changes resulting from irradiation, and the varied composition of post‐irradiation smears may lead to more accurate interpretation of the cytological findings.

The accuracy of cervicovaginal cytology testing in the detection of recurrent cervical carcinoma was investigated by correlating clinical and histology records with cytology smear results for two groups of patients. All patients had been treated with radiotherapy, with or without pelvic surgery, for carcinoma of the uterine cervix. Abnormal cervicovaginal smear results were present for 45.7% ( 32 70) of patients with histologically diagnosed recurrent cervical carcinoma including a correct prediction of recurrent cervical carcinoma in 32.8% ( 23 70) of cases. A cytologic diagnosis of recurrent carcinoma was present for 48.9% ( 23 47) of cases with local recurrence. The positive predictive value for a histologic diagnosis of recurrent cervical carcinoma after a positive cytology report for a group of 61 patients was estimated to be 98.4%. A cytologic diagnosis of locally recurrent cervical carcinoma preceded clinical signs in 15 61 (24.6%) of cases. These results indicate that although cervicovaginal cytology after radiotherapy for cervical cancer does not have high sensitivity it is a reliable test for the diagnosis of local recurrence. Cytologic examination of the vaginal vault or cervix after treatment may thus provide an early diagnosis of tumor recurrence or persistence, in some cases prior to the onset of clinical signs.

Summary: Papanicolaou smear screening for cervical cancer has become an established practice in most developed countries. This is because the cervix is relatively accessible to investigation and treatment, and early stages in the morphogenesis of cervical cancer are both recognizable and easily treated. The Pap smear is a valid test. It is simple, relatively inexpensive, reliable, and free of risk. Although the test has far from perfect sensitivity, it has high specificity, and false‐positive results are rare. In most reported series, the majority of false‐negative results have been found to be attributable to collection errors rather than laboratory errors. Despite the importance of Pap smear screening, controlled prospective trials have not been undertaken to determine its efficiency in reducing cervical cancer incidence and mortality. However, countries with well‐organized programmes, wide population coverage and correct follow‐up appear to have had some impact on mortality from cervical cancer. Nevertheless, coverage of high‐risk groups, particularly women over 40 years of age, remains the greatest problem. Recommendations on the frequency of testing vary considerably. Statistical models indicate triennial testing may deliver almost all of the effectiveness of annual testing at a substantially reduced cost, but the numerous reports of false‐negative results argue strongly in favour of annual screening. It is possible that these problems may be solved in the future by increasing the sensitivity of the test and/or by the use of additional tests.