DETECTION OF METASTASES IN SENTINEL LYMPH-NODES OF BREAST-CANCER PATIENTS BY MULTIPLE-MARKER RT-PCR

This study was undertaken to assess a multiple-marker RT-PCR and South ern blot assay for detection of metastases in frozen sections of senti nel lymph nodes from breast cancer patients. Sentinel lymphadenectomy was performed in 41 AJCC (American Joint Committee on Cancer) stage I- IIIA breast cancer patients and 57 sentinel nodes (SNs) were excised. The SN, which is the first node in the lymphatic basin to receive meta stases from the primary tumor, was identified using isosulfan blue dye . Hematoxylin and eosin (H&E), immuno-histochemistry (IHC) and RT-PCR were performed on adjacent sections of the SN. Six consecutive 12-mu m frozen sections of each SN were obtained for the RT-BCR assay to dete rmine expression of mRNA tumor markers C-Met, beta 1 --> 4GalNAc-T and P97. Metastatic breast cancer was detected by H&E in IO of 57 (18%) S Ns and by IHC in an additional 7 (12%). Only I of 17 (6%) SNs with met astases did not express any of the 3 tumor mRNA markers. C-Met, beta 1 --> 4GalNAc-T nd P97 tumor mRNA markers were expressed in 31 (78%), 2 1 (53%) and 25 (63%) of 40 SNs without metastases, respectively. At le ast 2 mRNA tumor markers were expressed in 25/40 (63%) histo-pathologi cally tumor-free SNs, whereas all 3 mRNA tumor markers were expressed in 17/40 (43%) SNs. Expression of ail 3 mRNA tumor markers in a SN was significantly higher in patients with a family history of breast canc er (p = 0.05), prior history of breast cancer (p < 0.05), infiltrating lobular carcinoma (p = 0.06), estrogen receptor-negative (p = 0.04) t umor or a higher Bloom Richardson score (p = 0.04). The multiple-marke r RT-PCR and Southern blot assay improves the detection of occult meta stases in the SN when compared to conventional H&E and IHC analysis. E xpression of all 3 tumor mRNA markers in the SN correlated with poor p rognostic clinico-pathologic factors compared to expression of 0 to 2 markers. (C) 1998 Wiley-Liss, Inc.