Predicting radioresistance in early glottic squamous cell carcinoma by DNA content

Treatments for throat cancer vary with the type of cancer found and the extent and location of disease. Localized tumors are highly curable with treatment involving either surgery or radiotherapy. In many cases, radiotherapy is preferred because it maintains function of the affected area. Tumor cells in some patients are resistant to radiotherapy and disease recurs after the initial treatment. It is important to be able to diagnose radioresistant cells before initiating radiotherapy so that time is not wasted using an improper treatment. Routine tissue examinations can not distinguish radioresistant cells from radiosensitive cells. This study assessed the relation between the DNA content of laryngeal (vocal cord) tumor cells and radioresistance. Radioresistant tumor cells of 14 patients and radiosensitive cells of 15 patients were obtained. DNA content of the cells was examined with flow cytometry to determine if the cells contained a normal (diploid) or abnormal (aneuploid) number of chromosomes. Samples from five patients with radioresistant tumor cells were found to have an abnormal number of chromosomes. There was no evidence that the radiotherapy itself caused the chromosomal abnormalities. These results suggest that tumor cells with an abnormal number of chromosomes are significantly more likely to be resistant to radiotherapy than cells with normal chromosome numbers. Further studies are needed to evaluate the use of DNA testing in deciding the best course of treatment for patients with laryngeal cancer. (Consumer Summary produced by Reliance Medical Information, Inc.)