Abstract P3-17-03: DCIS and the risk of breast cancer death - A case control study

Abstract

Abstract Introduction The risk of breast cancer death after a primary ductal carcinoma in situ (DCIS) is less than 2 % after 10 years. Whereas in situ recurrences do not influence survival, a 17-fold elevated risk of breast cancer specific mortality has been shown for invasive recurrences. Adjuvant radiotherapy (RT) effectively reduces recurrences after breast conserving surgery (BCS) for DCIS, but no studies have been able to demonstrate a survival benefit from adjuvant RT treatment or from choosing mastectomy instead of BCS. Here patient and tumour related risk factors for breast cancer death in women with a pure primary DCIS were studied. Patients and methods Women registered with a primary DCIS, between 1992-2012 in three of Sweden´s health care regions with a population of approximately 5.2 million, were enrolled in a nested case-control study. Out of 6,964 women with DCIS, 96 patients who later died from breast cancer were identified. Four controls per case (n=318) were randomly selected by incidence density sampling. We retrieved medical records and pathology reports and calculated OR with 95% CIs for various variables using conditional logistic regression. Results Of the 96 cases, 10 patients developed distant metastasis without a known local recurrence. In 56 patients death was preceded by an invasive ipsilateral recurrence and in 3 patients by a recurrent ipsilateral DCIS. Seven patients had invasive breast events in both the ipsilateral and the contralateral breast. Seventeen patients had contralateral invasive breast cancer and 3 patients contralateral DCIS. Multifocality and tumour size over 25mm (OR 2.6 (1.6 to 4.2)), positive or uncertain margin status (OR 2.8 (1.6 to 4.9)) and detection outside screening (OR 2.1 (1.2 to 3.9)) increased the risk of breast cancer death in univariate analysis, when adjusted for age and year of diagnosis. Suspicion of micro-invasion and nuclear grade 3 was associated with a nonsignificant increased risk, OR 1.8 (0.6 to 5.0) and 2.6 (0.9-6.5), respectively. The risk was not affected by age or treatment. Tumour size and margin status remained significant in the multivariable analysis, when adjusted for treatment and for contralateral breast cancer (OR 2.0 (1.2 to 3.7)). Conclusion In the present study, large tumours and positive or uncertain margin status were significant risk factors for later breast cancer death after a primary DCIS. More extensive treatment was not related to a lower risk. The significance of tumour biology and nuclear grade will be further examined and evaluated. Citation Format: Wadsten C, Garmo H, Fredriksson I, Sund M, Wärnberg F. DCIS and the risk of breast cancer death - A case control study [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-17-03.