Clinical and histological study on the histological complete response by preoperative chemotherapy in patients with squamous cell carcinoma of the oral cavity.

Tow hundred eleven patients with previously untreated squamous cell carcinoma of the oral cavity were treated with preoperative chemotherapy followed by definitive surgery between April 1976 and March 1990. A 12.8%(27/211) rate of histologically complete response was achieved. Patients who achieved a histologically complete response had a better 5-year cumulative survival rate than patients who were histogically positive for tumor in the surgically resected specimens (88.3% vs. 61.0%, p<0.025). Clinical and pathological pretreatment characteristics were analyzed to identify factors predictive of a histologically complete response. The malignancy grading was evaluated based upon three different morphological characteristics for tumor cell populations (type of differentiation, cellular atypism, mitotic index) and two characteristics for the tumor-host relationship (mononuclear inflammatory infiltrates, mode of cancer invasion). Negative histology in the surgically resected specimen was significantly correlated with the histological malignancy score (p<0.0001) as well as the T class (p<0.01). These results suggest that special consideration should be given to the histological malignancy score in addition to clinical manifestations in assessing the effect of preoperative chemotherapy and in the surgical treatment of oral squamous cell carcinoma.