Interpret what the results mean. Specifically, did the screening program have a significant impact on breast cancer mortality or not? 

One issue is that there may be time trends in breast cancer mortality that have nothing to do with screening. To control for this, a non-screening time period was identified (period C) during 1996€“2005 in each region during which breast cancer screening was not introduced (in the above region it would be from 1996€“2000). In addition, a time period 10 years prior to this non-screening period was identified during 1986€“1995 (period D) (in the above region from 1986 1990). The breast cancer mortality exposure in these two periods was as follows: 

Table 14.40: Comparison of breast cancer mortality between period C and period D

 

Transcribed Image Text:

# person-years # deaths Period C 1,866,741 (non-screening period from 1996–2005) (experience 10 years prior to period C) 396 Period D 1,898,989 494