Objective  Preoperative radiotherapy has an important role in the treatment of maxillary squamous cell carcinoma.The role of tumor regression grading after radiotherapy on survival has not been reported to date.This study evaluates pathologic tumor regression grading of maxillary squamous cell carcinoma after preoperative radiotherapy and its prognostic value in correlation to long-term survival.

  Methods  Between January 1994 to May 2003, 36 patients with maxillary squamous cell carcinoma who were treated with preoperative radiotherapy were examined.Patients were composed of 26 males and 10 females with a median age of 57.5 years.Two patients had stage Ⅱ, 12 had stage Ⅲ, and 22 had stage Ⅳ diseases.Patients received 40 Gy to 90 Gy(median 60) preoperative irradiation to the maxillary area involved.Then, radical resection of the tumor was performed after a median break of 23 days.Serial sections of whole surgical specimens were examined using hematoxylin and eosin stain.Tumor regression was graded according to the histopathological grading criteria of chemotherapy-and radiotherapy-induced tumor regression.The relationship between treatment outcome(local control and overall survival) and pathologic tumor regression was analyzed.

  Results  According to the grading criteria of pathologic tumor regression, 33.3% of the patients had Grade I, 16.7% had Grade Ⅱ, and 50.0% had Grade Ⅲtumor regressions.With a median follow-up of 51 months, 14 patients(38.9%) recurred and 13 locally recurred.Five-year overall survival and five-year disease-free survival were 70.9% and 60.5%, respectively.Overall survival and disease-free survival correlated with tumor regression grades, but the survival difference between Grade Ⅱ and Grade Ⅲ was not significant.When Grades Ⅱ and Ⅲ were combined as 'severe responders' and Grade I was designated as 'mild responders, ' the overall and disease-free survivals of the severe responders were 91.3% and 87.1%, respectively, whereas those of the mild responders were 30.0% and 8.3%, respectively(P < 0.001).Ten of the 12(83.3%) patients with mild responders developed local recurrence, whereas three of the 24(12.5%) patients with severe responders developed local recurrence(P < 0.001).Multivariate analysis confirmed that histopathological tumor regression after radiotherapy is an important prognostic factor in maxillary squamous cell carcinoma(P=0.001).

  Conclusion  Microscopic histopathological evidence of tumor regression after radiotherapy in maxillary squamous cell carcinoma is an important prognostic factor in the long-term survival of patients.