[118] Predictors of Local Recurrence (LR) in Patients with Ductal Carcinoma In Situ (DCIS) Treated by Breast Conserving Therapy (BCT): Value of the Memorial Sloan-Kettering (MSK) Nomogram

Laura C Collins, Ninah Achacoso, Zaineb Sharafali, Reina Haque, Larissa Nekhlyudov, Suzanne W Fletcher, Charles P Quesenberry, Laurel A Habel, Stuart J Schnitt. Beth Israel Deaconess Medical Center, Boston; Harvard Medical School, Boston; Kaiser Permanente, Northern CA, Oakland; Kaiser Permanente, Southern CA, Pasadena; Harvard Vanguard Medical Associates, Boston

Background: Various patient, treatment and pathologic factors have been associated with an increased risk of LR following BCT for DCIS. However, the strength and importance of individual factors has varied and the extent to which combining factors may improve prediction of risk is undetermined. Our aim was to assess, in a large population-based cohort of DCIS patients treated with BCT and known outcome, the value of the recently published MSK nomogram which combines clinical and pathologic features to predict the risk of LR in patients with DCIS treated with BCT.
Design: We identified patients diagnosed with a first unilateral DCIS between 1990-2001 treated with BCT at 3 integrated health plans. Slides from the index DCIS of patients with recurrences (cases=190) and controls (N=305) were reviewed. Regression methods were used to estimate relative risks (RR) of LR associated with clinical and pathologic factors. The MSK DCIS nomogram was then applied to the study population to compare the nomogram-predicted and observed risks for LR at 5 yrs.
Results: Among the 495 patients in the case-control analysis, the only pathologic features associated with increased LR in univariate analysis were larger lesion size (RR=3.0 for ≥20 low power fields of DCIS;95% CI 1.6-5.6) and involved (RR=2.9;95%CI 1.6-5.3), or close (<1mm)(RR=2.4;95%CI 1.6-3.8) margins. The risk estimates provide by the MSK nomogam showed approximately 90% correlation with the observed rates of LR and were stronger than those provided by evaluation of individual features.

RR of LR among women with DCIS in relation to MSK nomogram probability quartiles

MSK nomogram probability quartiles	5 yr Observed LR (%)	Nomogram Predicted RR	95% CI
Quartile 1 (2-<8)	4.8	1.0	Ref
Quartile 2 (8-<13)	8.5	1.8	1.0-3.4
Quartile 3 (13-<20)	20.9	5.2	2.6-10.3
Quartile 4 (20-53)	33.1	9.9	4.8-20.4

The associations between the nomogram-predicted and the observed LR rates were maintained when the analyses were restricted to patients treated with and without radiation therapy.
Conclusions: When applied to a population of patients with DCIS treated with BCT with known outcome, the MSK DCIS nomogram provided highly accurate prediction of the 5-year LR risk. This nomogram, therefore, may be a useful decision aid in selecting treatment for patients with DCIS.
Category: Breast

Monday, March 19, 2012 1:15 PM

Platform Session: Section B, Monday Afternoon