In situ and small invasive breast cancer register in Victoria, 1988 to 1992: tumour characteristics and patient management.

Abstract

All cases of in situ and invasive breast cancer are reported to the Victorian Cancer Registry. In 1988 a special subregister of all cases of carcinoma in situ and small invasive cancers up to 10 mm in size was established--the In situ and Small Invasive Breast Cancer Register (ISSIBCR). This was unique in being a population-based register and only possible because in Victoria, as in some other Australian states, all cancers including in situ disease are reported to the Central Cancer Registry. Between 1 January 1988 and 31 December 1992, 517 cases of in situ cancers and 892 invasive cancers of < or =10 mm in diameter were registered. During the study period, mammography screening was progressively introduced in Victoria and the number of cases, in both categories registered annually, doubled. The method of detection, the pathology and treatment of these lesions are described. It is of interest that 46.5% of the in situ cancers and 68.8% of the invasive cancers were detected either by the patient or her doctor on clinical examination. Total mastectomy was the method of treatment in 35.4% of in situ cancers and 42.0% of small invasive tumours. Only 38.0% of patients with small invasive cancers treated by breast-conserving surgery had irradiation of the affected breast. This register provides a valuable resource for the follow up of the natural history and outcome of treatment of the affected women.