Effectiveness of Population-Based Service Screening With Mammography for Women Ages 40 to 49 Years With a High or Low Risk of Breast Cancer: Socioeconomic Status, Parity, and Age at Birth of First Child

BACKGROUNDInvitation 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). METHODSThe 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. RESULTSThere 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. CONCLUSIONSThere 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. Cancer 2015;121:251-8. (c) 2014 American Cancer Society. The invitation to mammography screening of women aged 40 to 49 years is an issue of debate in many countries and a cost-effective alternative in those countries without screening among these women could be inviting only those women at higher risk. For the 3 risk factors in the current study, the relative effectiveness for the high-risk groups was found to be the same as or higher than that of the low-risk groups, indicating that screening of high-risk groups (eg, nulliparous women) may be an alternative.