[253] Molecular Subtypes of DCIS in African-American (AA) and Caucasian (CA) Women.

Bashar Sharaf Aldeen, Jining Feng, Hind Nassar-Warzecha. Wayne State University/Detroit Medical Center, MI; Johns Hopkins Medical Institutions, Baltimore, MD

Background: Molecular subtypes of breast cancer have been extensively studied in invasive carcinoma. Few studies have shown that the same classification could be applied to DCIS. We report the distribution of the molecular breast cancer subtypes in DCIS among AA and CA women, their association with prognostic factors and their impact on follow-up.
Design: TMAs were constructed from paraffin blocks of 94 DCIS cases selected from a cohort of 217 AA and 141 CA patients with DCIS diagnosed between 1996 and 2000 (data previously reported). We included cases with >1 focus of DCIS and available blocks. Each case was represented by two to five 1mm diameter spots (average=2.5 ±1.1) depending on the amount of DCIS; 3 TMA blocks were obtained and labeled by antibodies for ER, PR, HER2, KI67, CK5/6. The cases were subtyped as Luminal A (ER+ and/or PR+; HER2-), Luminal B (ER+ and/or PR+; HER2+), HER2+ (ER-, PR-; HER2+), basal-like (BL) (ER-, PR-, HER2-; CK5/6+) or unclassified triple negative (UTN) (ER-, PR-, HER2-,CK5/6-). Information on DCIS grade, size and follow-up were obtained.
Results: In this study, 67 (71%) patients were AA, and 27 (29%) were CA with mean age at diagnosis of 61 ± 12 y for AA and 58 ± 11 y for CA.
The table summarizes the distribution of DCIS subtypes by ethnic group and the DCIS grade (G), mean expression of KI67 (% KI67) and average DCIS size (T) in each group and subtype.

Mol. types, n (%)G1 / G3% KI67T (cm)Mol. types, n (%)G1 / G3% KI67T (cm)
Luminal A, 52 (80)16 / 1231.98Luminal A, 25 (92.6)5 / 63.11.35
Luminal B, 7 (10.8)1 / 422.59Luminal B, 2 (7.4)0 / 02.50.7
HER2+, 1 (1.5)0 / 181.5HER2+, 0n/an/an/a
BL, 2 (3.1)0 / 23.54.5BL, 0n/an/an/a
UTN, 3 (4.6)0 / 362.1UTN, 0n/an/an/a

Mean follow-up was 116±36 months. Recurrence was seen in 8 AA patients (2 DCIS, 6 inv. ca.) and 1 CA (DCIS). Margins in these cases were uninvolved. DCIS was luminal A in 6 AA and 1 CA and luminal B in 2 AA patients (they recurred as inv. ca.).
Conclusions: 1) In AA patients, the distribution of molecular subtypes is different in DCIS than that previously reported in invasive carcinoma; in the latter 55% were luminal A vs. 80% of DCIS lesions in our study. 2) HER2+, BL, and UNT DCIS were seen only in AA patients; in these subtypes, KI67 was higher than in luminal types and none had G1 DCIS. 3) The risk of recurrence of DCIS might not be higher in non-luminal subtypes, larger studies are needed to confirm this finding.
Category: Breast

Monday, February 28, 2011 1:00 PM

Poster Session II # 68, Monday Afternoon


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