Accrual rate-limiting factors in a Swedish randomised ductal carcinoma in situ (DCIS) trial - a demographic study

Abstract

In the last two decades the introduction of mammographic screening in the Western world has increased the number of diagnosed ductal carcinomas in situ (DCIS) considerably. In situ carcinoma of the breast is considered a heterogeneous disease, the natural history of which is not well known. Thus, appropriate treatment needs to be established. For this reason, a randomised trial studying the effect of breast conserving operation with or without postoperative radiotherapy was instituted in Southern Sweden in 1987. The aim of the present study was to assess patient accrual, identify limiting factors, and evaluate possible ways to influence these factors in order to increase patient accrual. Between 1987 and 1992, 331 patients had been registered with DCIS in the Regional Tumour Registry, 96 of which had been randomised. All 331 were subjected to chart review studying clinical data, mammography reports, cytology and pathology reports to identify inclusion and exclusion criteria according to the design of the trial. It was found that 5% (18/331) had an incorrect diagnosis of DCIS. According to the trial protocol 52% were not eligible (162/313). Fifty-eight per cent (n=88) of the 151 eligible patients had been correctly randomised. The most common reason for exclusion was lesion size. In 21% (66/313) the lesion was 'too large'. Several other limiting factors were identified such as in cytological and pathological definitions and reports, lack of information/awareness in certain physicians, patient reluctance to participate, which in turn may be influenced by the previous factor. With increased information to participating hospitals and considering the above given facts it should be possible to increase accrual from the 28% noted in the present consecutive demographic study to at least one-third of the diagnosed cases of DCIS