Bone marrow metastasis in nasopharyngeal cancer: early detection using EBER1 in situ hybridization

Previous studies have reported the abundant expression of EBER1 in primary nasopharyngeal carcinoma (NPC) metastatic to lymph nodes and bone marrow (BM). This study was done to research the use of EBER1 in situ hybridization to detect micrometastasis in the marrow of NPC patients.

A total of 41 patients who underwent BM biopsy either for routine pretherapeutic evaluation or suspected bone marrow metastasis were enrolled for study. Thirty-two patients underwent BM biopsy for routine staging examination (Group I) and 10 were examined for unexplained cytopenia, leukoerythroblastosis, disseminated intravascular coagulation, or extensive bone metastasis (Group II). The authors applied EBER1 in situ hybridization to investigate the expression of EBER1 in 42 BM specimens. Examinations were performed on paraffin embedded tissues using polymerase chain reaction-derived, digoxigenin-labeled EBER1 DNA probes.

Eight of 42 specimens (19%) were positive for BM metastasis. Just one (3%) had bone marrow involvement in Group I. However, seven (70%) were positive in Group II. All but one of them with bone marrow metastasis showed positive EBER1 in situ hybridization in the BM. Another patient suspected of having BM metastasis was negative for cytokeratin, but was positive for EBER1 in situ hybridization.

Routine bone marrow study is not recommended in the staging of NPC, since only 3% of patients had BM metastasis. EBER1 in situ hybridization of marrow specimens cannot detect malignant cells earlier in NPC, but can be usefully applied to cases of equivocal marrow metastasis.