Abstract P5-08-01: Contemporary local and regional recurrence rates in very young breast cancer patients
Authors: Aalders KC , Postma EL , Strobbe LJ , van der Heiden-van der Loo M , Sonke GS , Boersma LJ , van Diest PJ , Siesling S , van Dalen T 
Published: May 2016

Introduction: Historically, young breast cancer patients proved to have a poorer prognosis regarding survival and locoregional recurrence. Over the last two decades, the survival of breast cancer patients has improved substantially, while at the same time locoregional recurrence rates decreased. The diminishing recurrence rates in the overall breast cancer population and acknowledgement of tumor biology and intrinsic subtypes in relation to age, raise the question whether the historically high locoregional recurrence risk in young women has decreased over a time where systemic treatment has evolved, particularly for the aggressive tumor types that occur frequently in young women. The aim of this study was to evaluate contemporary local and regional recurrence rates in very young breast cancer patients in relation to tumor biology in the shape of intrinsic subtypes.

Methods: Women &lt;35 years of age who were operated for primary unilateral invasive breast cancer between 2003-2008 were selected from the Netherlands Cancer Registry. Patients were categorized according to intrinsic subtypes using hormone receptor and HER2 status. The 5-year risks of developing local recurrence (LR) and regional lymph node recurrence (RR) were estimated using Kaplan Meier statistics. The prognostic influence of different clinicopathological and treatment factors was assessed.

Results: A total of 1,000 patients were identified. The overall 5-year LR and RR rates were 3.5% and 3.7% respectively and a decreasing trend for both rates was observed over time.

Overall 5-year local, regional and distant recurrence rates over time in breast cancer patients &lt;35 years (n=1,000)  Local recurrence*Regional recurrenceDistant metastases  NRateNRateNRate2003n=21384.2%116.1%3617.8%2004n=212105.6%105.1%3819.2%2005n=18232.0%53.1%2514.6%2006n=17053.2%21.2%138.2%2007•n=11722.1%10.9%98.1%2008•n=10633.2%44.4%1010.0%Totaln=1,000313.5%333.7%13113.9%*Local recurrence (ipsilateral in-breast recurrence + new primary) •Fewer patients were included in the years 2007-2008 compared to earlier years due to the fact that some hospitals did not provide data for those years. Rates represent Kaplan Meier estimates

Intrinsic subtype proved to be a prognostic factor for both LR and RR (P=0.0556 and P=0.0141, respectively). Particularly HR-/HER2+ tumors were associated with high LR and RR rates. Patients with lymph node metastases at time of diagnosis had a higher RR-risk in both the total population (P=0.0349) as well as within the different intrinsic subtypes, although only significantly in the triple negative group (P=0.0401). Type of surgery did not influence the rate of LR and RR in this study.

Conclusions: Overall, the LR and RR rates in very young breast cancer patients were relatively low and decreased over time. The higher recurrence rates in this population were associated with the presence of more aggressive intrinsic subtypes. We emphasize that tumor biology should guide decision-making towards optimal treatment in this specific population. Although longer follow-up is needed, especially for this very young patient population, the results of this study provide important insight in the locoregional recurrence risks for this historically high-risk population.

Citation Format: Aalders KC, Postma EL, Strobbe LJ, van der Heiden-van der Loo M, Sonke GS, Boersma LJ, van Diest PJ, Siesling S, van Dalen T. Contemporary local and regional recurrence rates in very young breast cancer patients. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-08-01.