Abstract P4-15-09: Refined estimates of local recurrence risk in a clinical utility study: Integrating the DCIS score, patient age and DCIS tumor size
Authors: Manders JB , Solin LJ , Leonard CE , Mamounas EP , Lu R , Turner M , Baehner FL , White J 
Published: February 2018

Background:Better tools are needed to estimate the risk of local recurrence (LR; DCIS or invasive) after breast-conserving surgery (BCS) for pts with DCIS in order to inform treatment decisions. Traditional clinico-pathologic (CP) factors, e.g., age and tumor size, provide an average LR risk derived from clinical trials and population studies. The Oncotype DX 12-gene DCIS Score assay has been validated to provide individual 10 yr LR risk estimates (Solin JNCI 2013; Rakovitch BCRT 2015). Previously we reported the impact of the DCIS Score result on radiotherapy (RT) recommendations including the pre-assay LR risk and RT recommendation and the change in RT recommendation from pre- to post-assay (Manders Ann Surg Oncol 2016).Recently a patient specific meta-analysis (MA) combined data from E5194 and Ontario DCIS Cohort (ODC) adjusting for pertinent clinico-pathologic factors to provide refined prediction estimates of LR risk after BCS alone (Rakovitch ASCO 2017). Herein we applied these risk estimates integrating DS, tumor size and patient age with adjustment for diagnosis in the year 2000 or later to refine estimates of LR in DCIS patients from the Manders et al study.

Methods: 13 U.S. sites enrolled pts with DCIS treated with BCS alone from 3/2014 to 5/2015. Pts with LCIS but no DCIS, invasive BC, or planned mastectomy were excluded. Data were prospectively collected on CP factors, physician estimates of LR risk, and DCIS Score. Refined estimates of 10-yr risk of LR are presented by DCIS Score result category (0-38; 39-54; 55-100), age group (≥50 vs &lt;50 yr) and tumor size (≤1; &gt;1-2.5; &gt;2.5 cm).

Results: Of the 127 pts enrolled, median age was 60 yr,79.5% were postmenopausal. Median size was 8mm & 39% were ≤5mm. Median margin width was 3.0mm. ER and PR by IHC were positive in 89% and 78% of pts, respectively. For patients ≥50 yr with tumors ≤1 cm and low risk DS, the 10-yr LR risk ranges from 5.3-10.0%. A high DS result is associated with a higher 10-yr median predicted risk of LR in all subsets (table 1). The DCIS Score integrated with tumor size and patient age and the adjustment for diagnosis in 2000 or later provided risk estimates that are often lower than those provided by the DCIS Score alone without adjustment for diagnostic year. Using DS alone the percentage of patients with risk of LR &lt;8% was 0%; however, incorporating patient age and tumor size with the DS and adjusting for diagnosis in 2000 or later, it increased to 30.9% of patients.

Conclusions: Integration of the DCIS Score assay, that provides individual risk estimates of LR, with patient age and DCIS tumor size and adjusting for diagnosis in 2000 or later, provides refined estimates of 10-yr LR risk after BCS alone for DCIS. This integration enhances prognostic LR risk estimates and frequently provides lower risk estimates with which to guide individualized treatment decisions.

Distribution of 10-year risk of local recurrence using DCIS Score (DS), tumor size, and age, adjusting for diagnosis in 2000 or later.  Low DS (&lt;39)Inter DS (39-54)High DS (≥55)Tumor Size(cm)Age(Yr)NMedian (Min-Max)%NMedian (Min-Max)%NMedian (Min-Max)%≤1≥50457.0 (5.3-10)810.8 (10.2-11.8)1015.1 (12.9-18.6) &lt;50810.3 (7.4-12.1)414.9 (14.1-15.4)0 &gt;1-2.5≥50249.5 (7.3-12.6)914.2 (12.9-15.6)519.6 (16.5-20.4) &lt; 50216.4 (16.1-16.7)220.4 (19.8-21.1)122.2 (22.2-22.2)&gt;2.5≥50515.7 (14.9-23.7)0 138.4 (38.4-38.4) &lt;500 141.2 (41.2-41.2)149.3 (49.3-49.3)

Citation Format: Manders JB, Solin LJ, Leonard CE, Mamounas EP, Lu R, Turner M, Baehner FL, White J. Refined estimates of local recurrence risk in a clinical utility study: Integrating the DCIS score, patient age and DCIS tumor size [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-15-09.