Características clinicopatológicas dos cancros da mama diagnosticados em participantes, não participantes e não convidados ao programa de rastreio de cancro da mama no norte de portugal em (2003-2008): parte um – avaliação

The aim of this study was to evaluate the clinical and pathological characteristics of the invasive breast cancers diagnosed in women participant in the beginning of breast cancer screening programme, compared to cancers detected in non-participants and in not invited women. Data was retrieved from the population-based North Region Cancer Registry and from the organized population-based Breast Cancer Screening Programme (BCSP) of the north region of Portugal, and records were matched to select the three groups for comparison. In 125 screening participants, 75.8% of invasive breast cancers were ≤ 20 mm, 67.7% had no axillary lymph nodes metastasis and 58.1% were stage I. These characteristics were significantly more favourable than those found in breast cancers detected in non-participants (57 women) or not invited (314 women). After multivariable analysis, size remained the only distinguishing characteristic of breast cancers detected within the screening programme compared to the other two studied groups. Breast cancers detected in screening participants were significantly smaller, which is consistent with findings by other authors. The more favourable prognostic characteristics of the breast cancers detected in a population exposed to screening (including interval cancers) indicate a possible mortality reduction in the future.