Early detection of second breast cancers improves prognosis in breast cancer survivors

Patients and methods: Subjects were women with histology-verified second (invasive or in situ) breast cancer (N = 1044) in a breast centre in Florence (1980-2005). Symptom status, test, tumour stage, and outcomes data were obtained from clinical records and linkage with mortality registry. Disease-specific survival was measured from first cancer diagnosis to avoid lead-time bias. Sensitivity analysis was used to allow for length-time bias. Results: Second cancers (IBR = 455; CBC = 589; median age 60 years) were diagnosed in 699 asymptomatic and 345 symptomatic women (67% versus 3%, P < 0.0001). Mammography was more sensitive than clinical examination (86% versus 57%, P < 0.0001); however, 13.8% of cases were only identified clinically. Asymptomatic cancers were smaller than symptomatic for both IBR (P < 0.001) and CBC (P < 0.001). Early-stage tumours were more frequent in asymptomatic (58.1%) than symptomatic (22.6%) women (P < 0.0001). Fewer women with asymptomatic than symptomatic CBC had node metastases (P = 0.0001). Hazard ratio (HR) for asymptomatic (relative to symptomatic) detection was 0.51 (0.32-0.80) for IBR, 0.53 (0.36-0.78) for CBC, and 0.53 (0.40-0.72) in all subjects (P < 0.0001). Length bias-adjusted HRs ranged from 0.53 to 0.73. Conclusion: Detection of second breast cancers in the asymptomatic phase leads to detection of early-stage cancer and improves relative survival by between 27% and 47%.