Nuclear p53 accumulation by small‐sized adenocarcinomas of the lung

In order to evaluate the alterations of nuclear p53 accumulation in early stage adenocarclnomas of the lung, nuclear p53 accumulation by small‐sized peripheral adenocarcinomas of the lung was examined Immunohlstochemically. Peripheral adenocarcinomas of the lung, 2 cm or less in diameter, have been classified into two groups; one showing replacing growth of the pulmonary alveolar structure and the other showing non‐replacing growth. The former group has been subdivided into three microscopic subtypes: type A, localized bronchloloalveolar carcinoma (LBAC); B, LBAC with foci of pulmonary alveolar structural collapse; and C, LBAC with foci of active flbroblastic proliferation. Type C is thought to be advanced carcinoma, which develops progressively from types A and B. Two of 32 (6%) types A and B carcinomas, 37 of 133 (28%) type C carcinomas and 14 of 35 (40%) non‐replacement‐type adenocarcinomas showed positive nuclear staining for p53. The positive staining frequency was significantly higher for type C than for types A and B ( P <0.05). These results suggest that nuclear p53 accumulation occurs In the transition from the early to advanced stages of replacement‐type adenocarclnoma development and it may be a clinically useful Indicator of the degree of tumor malignancy.