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Radiotherapy is an integral part of the therapy for cancer of the head and neck. Unfortunately, not all cancers are equally susceptible to the effects of radiation, and many such cancers recur after radiation treatment. Researchers have speculated that some cancers are more resistant to irradiation because of purely physical factors such as their size and location. Other factors, such as the ulceration of a tumor and its stage of development, also seem to be important. A key factor seems to be the adequacy of the blood supply of the tumor; tumors which are poorly supplied with oxygen may have a greater chance of surviving radiation than those which are well oxygenated. However, two tumors which appear to be the same are often entirely different in their susceptibility to radiation. Some researchers have suggested that this is due to differences in the ability of the cancer cells themselves to repair the damage which is inflicted by the radiation. One way to approach this problem is to obtain cells from the cancers of human patients and grow them in tissue culture dishes, where there are no differences in oxygen supply. In this way, the response of cells to radiation may be studied without the influence of such variables. For this reason, cells were cultured from tumor specimens removed from 20 patients with cancer of the head and neck. Some of the cell lines which were established were found to be resistant to radiation, and others were radiosensitive. Radioresistant cells were obtained both from patients who had previously received radiation treatment and patients who had not. Similarly, radiosensitive cells were obtained even from patients whose cancer had recurred after radiotherapy. However, when only the radioresistant cells were compared, the amount of radiation required to kill a specified proportion of the cells from the previously irradiated patients was significantly higher than the radiation dose required to kill a similar fraction of cells from the other patients. These results indicate that resistance to radiation appears to be, at least in part, an intrinsic characteristic of the cancer cells themselves, and is not due entirely to the physical characteristics of the patient's original tumor. The physiological basis for this radiation resistance has not yet been identified, however. (Consumer Summary produced by Reliance Medical Information, Inc.)

This is a comprehensive retrospective study (1965–1984) of 130 patients with malignant parotid gland tumors. Patients were studied by comparison of presenting symptoms, histopathologies, treatments, disease-free intervals, and ultimate intervals. Facial paralysis was noted on presentation in 23% of the cases and regional neck node metastases were noted in 13%. Both findings correlated with prognosis. Seventy patients underwent surgery alone and 30 patients received combined therapy. The remaining patients were excluded from the study. The overall 5-year survival rate was 50%, with a 44% risk of recurrence. Fifty-six percent of the patients whose conditions subsequently recurred had their facial nerves sacrificed at time of surgery. Selected patients who received combined therapy experienced better local regional control and a prolonged disease-free interval as compared with those who underwent surgery alone. Combined therapy, however, provided no survival benefit for this group of patients. Adjuvant radiation therapy is recommended in the treatment planning of selected malignant tumors of the parotid gland.