Population-based Parameters for Breast Clinics in Brazil

Migowski, Arn

INTRODUCTION: Even in settings where mammographic screening coverage is high, a large proportion of breast cancer cases still presents as a palpable lesion. Nevertheless there are currently no parameters for the establishment of reference services for breast cancer diagnosis. The objetive of the study is to estimate population-based parameters for the necessity of diagnostic procedures for breast cancer, considering simultaneously symptomatic patients and those originating from the screening.

METHODS: The first step was to estimate the number of new cases of breast cancer based in data from cancer registries. The second step was to calculate the proportion of cases treated in a breast clinic that originally correspond to palpable lesions. We use two alternative approaches in this step: data from published studies or a estimative based on data from cancer registries. The third step was to calculate the total demand expected in the breast clinic, including suspected cases that have no confirmation of cancer. In this step we assume that the detection rate of cancer in subsequent screening examinations is about 0.4%, that 8.3% of screened women will have abnormal tests and that 10% of cases with palpable suspicious lesions referred by primary care will confirm cancer diagnosis. The last step is to calculate the demand for diagnostic procedures, considering the differences in the cases coming from palpable lesions and those coming from screening. Finally, the model was applied in one Brazilian state.

RESULTS: In accordance with the calculated parameters, the ratio between actual production and the estimated need was 7%, 18%, 54% and 71% respectively for fine needle aspiration, core biopsy, excisional biopsy and diagnostic mammography.

CONCLUSIONS: The estimated parameters shows that there are difficulties in accessing diagnostic confirmation, compromising the effectiveness of early detection programs and contradicting the common sense that only focuses on offering screening mammography.