Management of local residual primary lesion of nasopharyngeal carcinoma. II : Results of prospective randomized trial on booster dose

Abstract 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.