- Estrogen receptor (ER)-positive ductal carcinoma in situ (DCIS) is associated with higher risk for contralateral breast cancer (CBC) than ER− DCIS in the Surveillance, Epidemiology, and End Results (SEER) analysis.
Why this matters
- Most cases of DCIS are ER+, yet few patients receive hormonal therapy.
- Retrospective cohort study of 46,007 women with DCIS diagnosed between 1990 and 2002 in the SEER database.
- Multivariable competing risk regression was used to identify predictors of time from index DCIS to CBC (in situ or invasive).
- Funding: Patient-Centered Outcomes Research Institute.
- Most women with DCIS were white (82%); average age was 58.4 years.
- 75% of patients had ER+ DCIS.
- Median follow-up time was 14 years, 2 months.
- ER− DCIS was 40% less likely to have CBC than ER+ DCIS (HR, 0.6; 95% CI, 0.5-0.8).
- At 10 years, the model estimated that 5.3% (95% CI, 4.8%-5.9%) of ER+ DCIS will have CBC compared with 3.4% (95% CI, 2.7%-4%) of ER− DCIS, after adjusting for other factors.
- Possible underascertainment of CBC.