Abstract P1-17-07: Cancer management and outcome of very young non-pregnant patients with breast cancer diagnosed at 40 years or younger– GBG 29
Authors: S Seiler, S Schmatloch, M Reinisch, T Neunhöffer, M Schmidt, C Bechtner, F Marmé, M Wagner, V Möbus, T Reimer, A Kleine-Tebbe, B Sinn, E Stickeler, M Untch, W Janni, F Seither, S Loibl
Journal: Cancer Research (2019)

Abstract Introduction Breast cancer diagnosed in young women who are 40 years (yrs) or younger is a relatively rare disease. However, it represents the most common cause of cancer-related deaths in this age-group. Furthermore, young age at diagnosis is associated with an increased risk of recurrence and worse survival. To date, general concepts concerning oncological cancer management should be driven by clinicopathological tumor characteristics and should adhere to standardized protocols for patients in general, but little is known about the oncological cancer treatment and outcome of this very young women in today's clinical practice. Patients and Methods The breast cancer in pregnancy registry study (BCP/GBG29/BIG 03-02) is a multicenter, international, observational study. BCP was established to investigate the oncological management and outcome of breast cancer in pregnancy. Since 2014 non-pregnant patients who are 40 yrs or younger are eligible if diagnosed with histological confirmed invasive breast cancer, independent of the type of treatment as control cohort. All patients received oncological treatment according to local standards. In this study the following endpoints will be analyzed descriptively for the young non-pregnant women cohort: breast cancer staging at diagnosis, biological characteristics of breast cancer at diagnosis, diagnostic procedures, treatment modalities, toxicity, pathological complete response after neoadjuvant chemotherapy, disease-free survival and overall survival. Results From February 2014 until June 2018, 969 non-pregnant patients ≤40 yrs have been registered. The median age at diagnosis was 35 yrs (range 19-40). Overall, 90.1% of patients had a stage T1-2 at diagnosis and 67.1% of patients had negative lymph nodes. 86.7% of tumors were invasive ductal carcinomas and 4.1% lobular carcinomas. Grading (G) 3 was reported in 55.5%. 26.6% of tumors were luminal A-like (ER- and/or PgR-positive, HER2-negative, G1-2), 40.0% luminal B-like (ER- and/or PgR-positive, HER2-negative, G3 or ER- and/or PgR-positive, HER2-positive, any G), 7.7% HER2 positive non-luminal-like, and 25.7% triple negative breast cancers. 3.8% of young non-pregnant patients had metastatic disease at primary diagnosis. Conclusion This registry comprises a large cohort of young non-pregnant patients with breast cancer diagnosed at the age of 40 yrs or younger and provides important data about a modern breast cancer treatment as well as oncological outcome in this setting of young women. Further results including oncological management, toxicity, and survival will be presented at the meeting. Citation Format: Seiler S, Schmatloch S, Reinisch M, Neunhöffer T, Schmidt M, Bechtner C, Marmé F, Wagner M, Möbus V, Reimer T, Kleine-Tebbe A, Sinn B, Stickeler E, Untch M, Janni W, Seither F, Loibl S. Cancer management and outcome of very young non-pregnant patients with breast cancer diagnosed at 40 years or younger– GBG 29 [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-17-07.