Background: Invitation to mammography screening of women aged 40 to 49 years is a matter of debate in many countries and a cost-effective alternative in countries without screening among women aged 40 to 49 years could be inviting those at higher risk. The relative effectiveness of mammography screening was estimated for subgroups based on the breast cancer risk factors parity, age at time of birth of first child, and socioeconomic status (SES).
Methods: The SCReening of Young Women (SCRY) database consists of all women aged 40 to 49 years in Sweden between 1986 and 2005 and was split into a study and control group. The study group consisted of women residing in areas in which women aged 40 to 49 years were invited to screening and the control group of women in areas in which women aged 40 to 49 years were not invited to screening. Rate ratio (RR) estimates were calculated for 2 exposures: invitation and attendance.
Results: There were striking similarities noted in the RR pattern for women invited to and attending screening and no statistically significant difference or trend in the RR was noted by risk group. The RR estimates increased by increasing parity for parity of 0 to 2 and ranged from 0.55 (95% confidence interval [95% CI], 0.38-0.79) to 0.79 (95% CI, 0.65-0.95) for attending women. The RR for women with high SES was lower than that for women with low SES (RR, 0.72 [95% CI, 0.60-0.86] and RR, 0.79 [95% CI, 0.63-0.99], respectively). For women aged 20 to 24 years at the time of the birth of their first child, the RR was 0.73 (95% CI, 0.58-0.91) and estimates for other ages were similar.
Conclusions: There was no statistically significant difference noted in the relative effectiveness of mammography screening by parity, age at the time of birth of the first child, or SES.
Keywords: breast cancer; cancer screening; mammography; mortality; parity; risk factors; socioeconomic status (SES).
© 2014 American Cancer Society.