Breast cancer screening: a survival analysis in Algarve, Portugal

Abstract

Abstract Background Breast cancer is the leading cause of cancer death in women worldwide and it is an health concerns in Algarve, a southern region in Portugal. The mammographic screening is performed with the aim of early detection and reduce mortality due to breast cancer. However, there are some controversies with mass screening due to overdiagnosis, overtreatment and false-positive results. We examined whether tumor characteristics were different for women with breast cancer diagnosed via mass screening compared with women non-participants of the screening programme. We also explored the survival differences between the groups. Methods We performed a cohort study using the data obtained from Registo Oncológico Nacional, the Portuguese national cancer registry, and the regional breast cancer screening programme. The Chi-squared test, Fisher exact test, and Mann-Whitney test was performed to test the differences with the screening status. For survival analysis, the Kaplan-Meier curves were examined and then we used Cox regression to explore the differences in survival by screening status. Results The worsen stages and the HER2 expression were significantly associated with being a non-participant of the regional screening programme. The survival time was also different with women screened having a bigger survivance when compared with non-participant. After the adjustment for variables associated with screening status, there was no evidence that the risk of women with breast cancer screening-detected was different from women non-participant. Conclusions Screening status was associated with a better tumor stage and non HER2 expression. Despite the lead-time bias, it was not identified survival differences between screening status, which is in agreement with other breast cancers survival analysis. These results are in agreement with the commission of the regional breast cancer screening programme in identifying precociously the breast cancers. Key messages Breast cancer screening in Algarve identify precociously the breast cancers. There is no evidence that the risk of women with breast cancer screening-detected was different from women non-participant in breast cancer screening in Algarve.