Evaluation of service mammography screening impact in Italy. The contribution of hazard analysis

Abstract 12,987 invasive breast cancer cases were diagnosed in women aged 50–69 upto the year 2001 in nine Italian areas where a screening programme was active. Cases were followed up in 2005 for a total of 1921 breast cancer failures. The 10-year survival rates were 85.3% for the invited group against 75.6% for the non-invited. A time dependent analysis was performed using 5-year intervals. Crude hazard ratios for the invited group in comparison to the not invited group were 0.52 and 0.64 respectively in the (0–5) year and [5–10] year time windows. Hazard ratio adjusted for tumour characteristics was 0.96 in the [5–10] year time window, suggesting minimal or any length bias. Consistent with the results of randomised trials, these analyses of service screening data document a mortality reduction of 36% at 5–10 years after diagnosis.