The use of microfluorometry to study DNA in nasopharyngeal carcinomas: a possible prognostic tool?

A microfluorometric method was used to determine the nuclear DNA content in the nasopharyngeal carcinomas (NPC) of 25 patients treated before 1983. Eleven patients are still alive with no evidence of disease (NED), while the rest died of their disease (DOD). All of the patients received a cycle of radiotherapy, while some also received chemotherapy or neck dissections. The neoplastic cells studied were taken from the original biopsy blocks, deparaffinized, isolated by enzymatic treatment and mechanical fragmentation, and then Feulgen-stained. The cytofluorometric measurement was carried out by a microphotometer equipped for fluorescence excitation and connected to a computer. This method allowed us to construct a histogram of the DNA content in the neoplastic cells. Different neoplastic classes were identified and represent the heteroclonality of the tumor, which can be expressed by the heteroclonality index (HCT). From the collected data it appears that the NED patients all had a low HTC (less than 1) and only 7 of the DOD patients had low HTCs (less than 1). Six of the DOD patients with a low HTC were in advanced stages of their tumor at the time of diagnosis, while the remaining patient did not complete his treatment. Our results show that the DNA analysis of the NPC cell population may offer a useful tool in predicting the biological behavior of this tumor and also improving its treatment.