Abstract P6-08-01: Contemporary risk of local, regional and contralateral breast cancer recurrence
Authors: Aalders Kim C , van Bommel Annelotte CM , van Dalen Thijs , Sonke Gabe S , van Diest Paul J , Boersma Liesbeth J , van der Heiden-van der Loo Margriet 
Published: May 2015

Abstract
Background
Long-term follow-up of breast cancer patients aims to detect curable recurrence, and focuses on ipsilateral in-breast recurrence (LR), regional lymph node recurrence (RR) and contralateral breast cancer (CBC). In recent years there is mounting evidence of a decrease in locoregional recurrence rates. Non-surgical-treatment modalities have evolved extensively, while surgery has become less invasive over the last fifteen years. The present study aimed to address contemporary loco-regional recurrence rates evaluating time trends and the role of contributing factors.
Material and methods
The Netherlands Cancer Registry was searched for all female patients diagnosed and operated for a unilateral primary breast cancer (pT1-2,anyN,M0) between 1-1-2003 and 31-12-2006. Exclusion criteria were previous cancer, neo-adjuvant chemotherapy or incurable disease. Data on 5-year follow-up were available from hospital records and included the first site of recurrence and contralateral breast cancer (CBC). The 5-year risk of developing LR, RR and CBC were estimated using Kaplan Meier curves. Patients were censored at time of death, lost to follow-up or the development of distant metastases. Prognostic influence of various patient- and disease characteristics was assessed.
Results
A total of 35.006 eligible patients were identified. The 5-year rates of LR, RR, and CBC are presented in Table 1. The risk of CBC was higher than LR and RR. Over time, the rates decreased significantly for all three endpoints.
Table 1. Overall 5-year risk of local, regional and contralateral recurrence and distant metastases over time (period 2003-2006) Local recurrence(a)Regional recurrenceContralateral breast cancer no. of eventsrate (%)no. of eventsrate (%)no. of eventsrate (%)2003 (n=8933)1852,40%861,11%2273,08%2004 (n=9048)1812,35%831,07%1892,51%2005 (n=9055)1441,84%750,95%1902,49%2006 (n=7970)1311,87%500,70%1462,05%Overall (n=35.006)6412,12%2940,96%7522,55%(a)Local recurrence (ipsilateral in-breast recurrence + new primary). Rates represent Kaplan Meier estimates
The LR-rate was lower with breast conserving surgery (BCS) vs. amputation (1.8% vs. 2.5%), T1a-b vs. T1c-T2 tumors (2.0% vs. 2.5%), ER+ vs. ER- tumors (1.8% vs. 3.5%) and inversely related with age (highest in pts. &lt;35 yrs: 2.9%). LR rate seemed independent of HER2 status.
The 5-year RR-rate was 0.9% for N0 patients, and decreased from 1.0% to 0.7% over time. The risk of RR after amputation decreased from 1.8% to 0.9% over time, but was higher than after BCS (1.6% vs. 0.6%). Overall, the RR-rate was highest in the N&gt;1 group (1.4%) and the triple negative group (2.0%).
The CBC-rate was lower for patients who received chemotherapy (CT) than for patients who did not (1.6% vs. 3.1%). The CBC-rate only decreased over the years in the CT-group (3.7% to 2.5%).
Conclusions
Loco-regional recurrence rates have decreased substantially in recent years and have become very low. For the vast majority of patients the risk of LR is substantially lower than the risk of CBC and the risk of RR is rarely larger than 1.0%. These low rates might reflect improvements in systemic treatment.
Citation Format: Kim C Aalders, Annelotte CM van Bommel, Thijs van Dalen, Gabe S Sonke, Paul J van Diest, Liesbeth J Boersma, Margriet van der Heiden-van der Loo. Contemporary risk of local, regional and contralateral breast cancer recurrence [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P6-08-01.