A recent population-based cohort study in England has shed light on the long-term risks of invasive breast cancer and breast cancer-related death following the diagnosis of non-screen detected ductal carcinoma in situ (DCIS). The study, conducted from 1990 to 2018, included 27,543 women and compared the risks for women diagnosed with DCIS outside the NHS breast screening program with those diagnosed via the screening program.

The study found that by the end of 2018, 3651 women with non-screen detected DCIS had developed invasive breast cancer, which was more than four times higher than expected based on national cancer incidence rates. This elevated risk persisted throughout the follow-up period, particularly among women aged 60 years. Additionally, the cumulative risks of invasive breast cancer and breast cancer death were found to be higher for women with non-screen detected DCIS compared to those with screen-detected DCIS. However, the absolute differences at 25 years were relatively small, with a 1.6 percentage point difference for invasive breast cancer and a 0.6 percentage point difference for breast cancer death.

Furthermore, the study revealed that there is no evidence of a decrease in invasive breast cancer rates for women whose DCIS was diagnosed more recently. However, the breast cancer death rates for women diagnosed more recently have shown a significant decrease, likely attributable to improved treatment of invasive disease.

The findings of this observational study also indicated that breast cancer mortality rates were similar across various treatment groups.