Fig. 5　Overall survival according to the curability

Patients in the histologically curative operation（R0） group（grey line） showed significantly better prognosis than those in the non-curative group（R1, R1cis, R2）（black line; P＜0.01）.
R0 no residual carcinoma, R1 carcinoma remained histologically（histologically positive for resected margin）, R1 cis R1 with superficial spreading, R2 carcinoma remained macroscopically.