Comparison of Estrogen, Progesterone and Her2 Receptors in Primary Breast Cancer and Paired Metastatic Lymph Nodes: An Immunohistochemical Study

Immunohistochemistry (IHC) of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (Her2) are important prognostic factors of breast cancer. However, discordance between IHC findings of primary tumor and ipsilateral metastatic lymph nodes (IMLNs) has been reported that might affect the criteria for adjuvant therapies in breast cancer in the future.
Sample size of the current study was estimated 50 (Macnemar test). We performed IHC for ER, PR, and Her2 on IMLNs of 50 paraffin embedded blocks of breast cancer patients with regional lymphadenopathy during the period. All-red score 2 was regarded as negative and 3 as positive for ER/PR. Her2 results were classified to 1 ( 0 and 1), 2, and 3. We used SPSS 16 to insert and analyze the data.
Mean age of patients was 49 yrs, and mean tumor size was 4.8 ± 3.53 cm. Twenty-four samples were pN1, 17 pN2, and 9 pN3. ER and PR were positive in 50% and 52 % of tumoral samples and 78% and 76% of IMLNs, respectively (fisher exact test, P = 0.003 and P = 0.011, respectively). The discrepancy between IHC of primary tumor and IMLNs for ER, PR and Her2 was 32% (P = 0.000), 24% (P = 0.002), and 48%, respectively. Overall, 34 patients (68%) showed disagreement in at least one of their receptors.
Discrepancy between IHC results of primary tumor and IMLNs was significant. Since metastatic clones in metastatic lymph nodes (MLNs) are potential sources of systemic metastasis, routine IHC on MLNs could play an important role in determining prognosis, indication for FISH, and finally, choosing adjuvant treatment.