MANAGEMENT OF LOCAL RESIDUAL PRIMARY LESION OF NASOPHARYNGEAL CARCINOMA .2. RESULTS OF PROSPECTIVE RANDOMIZED TRIAL ON BOOSTER DOSE

Although the question of booster dose for residual primary lesion arises in only 5% of nasopharyngeal carcinoma patients receiving radiotherapy, it poses a difficult problem for clinicians and should be followed. Hence, to test the validity of booster dose for residual primary lesion of nasopharyngeal carcinoma, a prospective randomized trial has been designed and carried out since January 1980. All patients who had a residual lesion in the nasopharynx at 70 Gy were biopsied. Those pathologically positive for cancer were randomized into two groups: (a) positive radiation group (PRG): patients were given further irradiation to a total dose of 90 Gy by the cone-down and assault technique, and (b) positive observation group (POG): patients were given no more irradiation but were followed periodically together with those who were pathology negative (NOG). A total of 78 patients were entered. The validity of booster dose was shown by the 5-year survival rates of the PRG, POG and NOG groups: 75% ( 3 4), 33% ( 1 3), and 58% ( 14 24), respectively. The total local recurrence rates of these groups were 6% ( 1 16), 36% ( 5 14), and 4% ( 2 48), respectively. The authors believe that booster dose for pathology positive residual lesion in the nasopharynx is necessary. The four factors leading to the development of a local recurrence are: (a) residual primary lesion proved positive by pathology but left unboosted, (b) well differentiated squamous cell carcinoma in the original primary lesion, (c) mild radio-response in the cancer parenchyma, and (d) mild radio-response in the interstitial tissue. © 1990.