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

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.