Long-term prognosis of breast cancer detected by mammography screening or other methods
1 Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Biomedicum Helsinki 2U, Tukholmankatu 8, PO Box 20, FI-00014 Helsinki, Finland
2 Molecular Cancer Biology Program, Biomedicum Helsinki, University of Helsinki, Tukholmankatu 8, PO Box 20, FI-00014, Helsinki, Finland
3 Departments of Palliative Medicine and Oncology, Tampere University Hospital and University of Tampere, Teiskontie 35, PO Box 2000, FI-33521,Tampere, Finland
4 Department of Oncology and Hematology, Oulu University Central Hospital, Kajaanintie 50, PO Box 20, FI-90029, Oulu, Finland
5 Cancer Center, Kuopio University Central Hospital, Puijonlaaksontie 2, PO Box 1777, FI-70211, Kuopio, Finland
6 Institute of Medical Technology, University of Tampere and Tampere University Hospital, Biokatu 8-12, PO Box 2000, FI-33520,Tampere, Finland
7 Department of Oncology, Helsinki University Central Hospital, Haartmaninkatu 4, PO Box 180, FI-00029, Helsinki, Finland
8 Division of Global Health, Karolinska Institutet, SE-17177, Stockholm, Sweden
Breast Cancer Research 2011, 13:R134 doi:10.1186/bcr3080Published: 28 December 2011
Previous studies of breast cancer have shown that patients whose tumors are detected by mammography screening have a more favorable survival. Little is known, however, about the long-term prognostic impact of screen detection. The purpose of the current study was to compare breast cancer-specific long-term survival of patients whose tumors were detected in mammography screening compared with those whose tumors were detected by other methods.
Breast cancer patients diagnosed within five specified geographical areas in Finland in 1991 and 1992 were identified (N = 2,936). Detailed clinical, treatment and outcome data, as well as tissue samples, were collected. Women with in situ carcinoma, distant metastases at the time of primary diagnosis and women who were not treated surgically were excluded. The main analyses were performed after excluding patients with other malignancy or contralateral breast cancer, followed by sensitivity analyses with different exclusion criteria. Median follow-up time was 15.4 years. Univariate and multivariate analyses of breast cancer-specific survival were performed.
Of patients included in the main analyses (n = 1,884), 22% (n = 408) of cancers were screen-detected and 78% (n = 1,476) were detected by other methods. Breast cancer-specific 15-year survival was 86% for patients with screen-detected cancer and 66% for patients diagnosed using other methods (P < 0.0001, HR = 2.91). Similar differences in survival were observed in women at screening age (50 to 69 years), as well as in clinically important subgroups, such as patients with small tumors (≤ 1 cm in diameter) and without nodal involvement (N0). Women with breast cancer diagnosed on the basis of screening mammography had a more favorable prognosis than those diagnosed outside screening programs, following adjustments according to patient age, tumor size, axillary lymph node status, histological grade and hormone receptor status. Significant differences in the risk of having future contralateral breast cancer according to method of detection were not observed.
Breast cancer detected by mammography screening is an independent prognostic factor in breast cancer and is associated with a more favorable survival rate as well as in long-term follow-up.