Abstract
To investigate the malignant potential of T1 sized type-D and type-F pulmonary adenocarcinoma (PA), the proliferative and invasive growth potentials of the tumor cells were examined. Ten surgically resected cases of type-D PA and eight cases of type-F PA, each classified as T1 and less than 3 cm in the largest dimension, were selected for this study. None of these cases had received pre-operative chemotherapy or radiotherapy. Using the Ki-67 labeling index (LI) for tumor cells, which indicates the proliferating growth potential, tumors averaged 42.80±19.66% in type-D PA, and 28.38±6.58% in type-F PA. This labeling index showed specific relationships with tumor dimension and lymph node involvement in both type-D and type-F PA. The cathepsin D-positive rate, indicative of invasive growth potential, was 70.0% in type-D PA, and 50.0% in type-F PA. The cathepsin D-positive rate showed specific relationships with tumor dimension and level of lymph node involvement in type-D PA, but only with dimension in type-F PA. We conclude that the malignant potential of type-D PA depends on the Ki-67 LI and the cathepsin D expression in the tumor cells, however for type-F PA the malignant potential depends on the Ki-67 LI. These findings should be useful in determining prognosis in routine pathologic examinations.
