The flow-cytometric analysis of nasopharyngeal carcinoma treated with stereotactic radiosurgery

Stereotactic radiosurgery has been used in the treatment of nasopharyngeal carcinoma. To analyze the effect of radiosurgery on the flow cytometry DNA index and progression of cells through the cycles, 4 recurrent nasopharyngeal carcinoma cases were treated with stereotactic radiosurgery. The distribution of cells through the cycles was measured by flow cytometry at various times thereafter. The 50% isodose curve was placed at the tumor margin and the margin dose was 20 Gy. Biopsy of the nasopharynx was performed before and 1, 3, and 6 months after treatment. The specimens were then subjected to flow-cytometric analysis. The percentage of cells in the S phase was 27.6 +/- 1.0, 14.6 +/- 0.8, 12.1 +/- 1.6 and 11.3 +/- 1.3%; the proliferating index was 39.1 +/- 1.4, 17.0 +/- 0.9, and 14.3 +/- 1.2 and 14.1 +/- 1.5%, and the DNA index was 1.5 +/- 0.1, 1.6 +/- 0.2, 1.7 +/- 0.1 and 1.9 +/- 0.1 before and 1, 3, and 6 months after treatment, respectively. It is suggested that the percentage of cells in the S phase and the proliferating index decreased to normal after treatment with stereotactic radiosurgery. This study explores the preliminary radiobiological effect of stereotactic radiosurgery on the DNA content and the distribution of cells through the cycles in nasopharyngeal carcinoma.