[2088] Review of ER, PR, and Her-2/Neu Immunohistochemisty Should Be Performed for Breast Cancer Patients Transferring Care to Another Institution

Julie M Jorns. University of Michigan, Ann Arbor, MI

Background: Breast cancer patients receive vastly different care depending on ER/PR and Her-2/neu status. Even small differences in interpretation may alter treatment decisions, from which ancillary tests are ordered to which drugs patients ultimately receive.
Design: An electronic database query (1/08-6/11) identified patients seeking second opinion or transfer of care for the diagnosis of invasive breast carcinoma or ductal carcinoma in-situ. Patients were those who had pathology slides, including ER, PR, &/or Her-2/neu immunostains, performed at a contributing institution and reviewed at a referral center. ER/PR were interpretated as negative, weakly positive, and positive if <1%, 1-10%, and >10% of tumor showed nuclear positivity, respectively. Her-2/neu was interpreted as negative, equivocal, and positive if there was 0-1+, 2+, and 3+ membranous staining, respectively. ER, PR, & Her-2/neu status was assigned by retrospective review of reports from contributing and referral institutions. Discordance was defined as any change in interpretation for one or more reviewed stains. Future plans are to review all discordant cases to assess clinical impact.
Results: Partial analysis yielded 700 cases, 640 (91.4%) of which had concordant and 60 (8.6%) had discordant interpretations. Patients in both groups had no significant difference in clinicopathologic characteristics.

Clinicopathologic Features
 Concordant (N=640)Discordant (N=60)
Age (yrs)54.052.9
Sex (N, %)  
F638 (99.7)60 (100)
M2 (0.3)0 (0)
Procedure (N, %)  
Core489 (76.4)47 (78.3)
Excision/Lump128 (20)11 (18.3%)
Mastectomy14 (2.2)1 (1.7)
Other9 (1.4)1 (1.7)
Histology (N, %)  
DCIS/microinvasive71 (11.1)6 (10)
IDC500 (78.1)46 (76.7)
ILC51 (8)7 (11.6)
Other18 (2.8)1 (1.7)
Grade (N, %)  
1152 (23.7)10 (16.7)
2247 (38.6)19 (31.7)
3241 (37.7)31 (51.6)

Of the 60 discordant cases 55 (91.7%) had discordance in hormonal receptor (ER &/or PR) interpretation, 3 (5%) had Her-2/neu discordance, and 2 (3.3%) had ER/PR and Her-2/neu discordance. Discordance was most often due to ER/PR (PR>ER) disagreement of single interval change.

Discordant Cases
 Neg ⇔ Weak/Equiv (N, %)Weak/Equiv ⇔ Pos (N, %)Neg ⇔ Pos (N, %)
ER (N=60)8 (13.3)9 (15)0 (0)
PR (N=60)21 (35)17 (28.3)3 (5)
Her-2/neu (N=50)3 (6)2 (4)0 (0)

Conclusions: ER, PR, and Her-2/neu interpretation is subject to interobserver variability, this study resulting in small but significant discordance rate of 8.6%. As their interpretation may change clinical management review should be performed for patients seeking second opinion or care at another institution.
Category: Quality Assurance

Monday, March 19, 2012 1:00 PM

Poster Session II # 278, Monday Afternoon


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