Zinc levels are known to be elevated in certain cancer tissues. In this study, zinc content in metastatic and primary nasopharyngeal carcinoma (NPC) cells were quantitated by X-ray microanalysis at the ultrastructural level. Zinc levels of cancer cells derived from the cervical lymph node of a patient with metastatic carcinoma and that from the nasopharynx biopsy of another NPC patient with no clinical evidence of secondary spread, were analyzed. X-ray microanalysis revealed significantly higher cellular zinc levels in metastatic NPC cells. Zinc is a known anti-apoptotic agent and tumor response to radiotherapy is linked with apoptosis or programmed cell death. Raised zinc levels observed here could provide the biological basis for the observation of a higher percentage of distant metastasis in cervical node positive NPC patients treated by radiotherapy (the mainstay of treatment for NPC) as compared to those without regional nodal disease.

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