[118] Comparison of Oncotype DX™ Recurrence Score by Histologic Subtype of Breast Carcinoma

Philip E Bomeisl, Cheryl L Thompson, Lyndsay N Harris, Hannah L Gilmore. University Hospitals Case Medical Center, Cleveland, OH; Seidman Cancer Center, Cleveland, OH

Background: Oncotype DXTM is a commonly used 21 gene assay that predicts the benefit of chemotherapy for node-negative patients with all types and grades of estrogen receptor-positive breast cancer. Results are used to determine which patients may benefit from adjuvant chemotherapy. Though some data exists demonstrating that traditional pathologic features can predict score, there is little information published correlating specific histologic subtype of cancer and recurrence score (RS).
Design: The pathology database was searched for all Oncotype DXTM reports from 1/1/2008 to 10/1/2012. The corresponding original pathology reports were reviewed to determine histologic subtype, grade, and ER/PR/HER2 status. The pathologic features were compared with the Oncotype DXTM report data.
Results: A total of 146 cases were identified. The histologic subtypes seen were invasive ductal carcinoma (IDC, 71.2%), invasive lobular carcinoma (ILC, 15.8%), mixed invasive ductal and lobular carcinoma (ID+LC, 8.9%), invasive mucinous carcinoma (IMC, 2%), mixed invasive ducal and mucinous carcinoma (ID+MC, 1.4%) and tubular carcinoma (TC, 0.7%). These categories were stratified by grade and RS. Not unexpectedly, amongst the IDCs, higher grades were associtaed with a much greater likelihood of having a high RS (p<0.001). Most tumors with high RSs were IDCs. 15.4% of all IDC vs. 2.1% of the remainder of the tumor histologic types fell into this category.

Recurrence scores (RS) by histologic subtype and grade
 Low (0-17)Intermediate (18-30)High (31-100)
IDC (total)523616
Grade 120100
Grade 230205
Grade 32611
ILC (total)10130
Grade 1230
Grade 28100
ID+LC (total)1021
Grade 1300
Grade 2720
Grade 3001
IMC (total)030
Grade 1030
ID+MC (total)200
Grade 2200
TC (total)100
Grade 1100
Table 1

Conclusions: IDCs have the highest likelihood of all subtypes to have high RSs. From this data set, ILCs, IMCs (pure or mixed) and TCs were unlikely to have high RSs. Pure IMCs consistently had intermediate RSs despite the fact that they have favorable prognoses as compared with other subtypes. Clinicans may want to use Oncotype DXTM more sparingly in certain histologic subtypes of carcinoma and should interpret the results from special histologic subtypes with caution. Additional cases from special subtypes of breast carcinoma should be studied to confirm these results.
Category: Breast

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 32, Wednesday Morning


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