Breast cancer (BC) is the most common cancer among women in Quebec. Screening plays an important role in reducing its burden. BC incidence in adult women with congenital heart disease (ACHD) has not been studied.

To compare ACHD women BC incidence rates to general population. To assess if ACHD women have comparable BC screening rates to non-ACHD women.

The Quebec CHD database which includes 84,498 CHD patients was used to calculate the incidence rate of BC among ACHD women in 1992–2009. Age-specific and cumulative incidence of BC were calculated. The age-standardized incidence rate ratio (ASIR) was also calculated using direct standardization to compare rate to the general population and for 4 periods of time. Yearly BC screening participation rate was measured from 1989–2009, as the percentage of screen-eligible women, aged 50–69, who completed at least one mammogram within the 24 months. We compared it to the rate in Quebec general population.

The incidence rate of BC progressively increased with advancing age with 21% of cases<50y, 45% in 50–69y. In our cohort, 1 out of 10 women (9.8%; 95% CI, 8.6–11.0) developed BC over the course of adulthood. The ASIR was less<1 before 2006 and 1.25 (95% CI, 1.23–1.26) in 2006–2009 indicating an increased risk of BC among ACHD women than general population in the recent era. Compared to the general population, ACHD women had lower yearly BC screening participation rates from 1989 (18.3% vs. 22.1%) to 2009 (64.6% vs. 67.9%) and still inferior to the official target participation rate (70%).

The incidence of BC in ACHD women has increased and is now higher than the general population. Primary care physicians and cardiologists should collaborate to ensure appropriate cancer screening for ACHD women among whom attention to cancer screening may be overlooked. Further analyses will assess the impact of radiation from cardiac imaging and BC risk in this high exposed population.