Two hundred and eleven surgically resected primary lung tumors were studied 
immunohistochemically. According to histologic type, they were 129 
adenocarcinomas, 56 squamous cell carcinomas, 4 small cell carcinomas, 8 large 
cell carcinomas, 8 adenosquamous cell carcinomas, 5 so-called carcinosarcomas 
and 2 other tumors. Immunohistochemical expression of p53 and bcl-2 was studied 
in relation to the disease-free survival. Among the 211 patients with lung 
cancer, 109 were positive for p53 expression, and there was no significant 
relationship between p53 expression and sex, or clinicopathological stage and 
size of the tumor, although the patients with squamous cell carcinoma had a 
significantly higher frequency of p53 expression than those with 
adenocarcinomas. The frequency of p53 expression was significantly higher in the 
patients with poorly differentiated adenocarcinomas than in those with other 
histologic types. Seventy four of the 211 patients were positive for bcl-2 
expression and bcl-2 expression was higher in the stage I patients and patients 
with small lung tumors 2cm or less in diameter than in the other patients. The 
patients with adenocarcinoma had a higher frequency of expression than those 
with squamous cell carcinoma but no difference was found in the histological 
differentiation of the tumor. The 5-year survival of patients positive for p53 
expression was poorer than that of those with negative expression and the 
survival rate was higher in the patients positive for bcl-2 expression than in 
those with negative expression. These findings suggested that the expression of 
p53 and bcl-2 is a useful marker of follow-up and prognosis, but will require 
more data concerning the mechanism of carcinogenesis. Seven cases of primary 
lung cancer were examined for genetic abnormality of the p53 gene. cDNA was 
synthesized from total RNA of primary tissues of lung cancer using oligo (dT) 
primer and reverse transcriptase and polymerase chain reaction (RT-PCR), and 
PCR-single strand conformation polymorphism (SSCP) analysis were performed. Five 
patients gave a positive result upon PCR-SSCP analysis of the p53 gene. To 
confirm the results of PCR-SSCP analysis, their nucleotide sequences were 
further analyzed and four of them had point mutations at different codons (154, 
176, 207, 236) and one had deletion of one nucleotide (245) in exon 5 and 8. 
Fifteen percent of 26 patients with small peripheral lung adenocarcinomas less 
than 2cm in diameter were already advanced in stage and various factors such as 
vascular invasion, pleural involvement and degree of scar grade were higher than 
in patients with clinicopathological stage I. In advanced cases, the frequencies 
of p53 expression was higher than in stage I cases. Concerning the relationship 
of the degree of scar grade to PDGF-B expression, we demonstrated the production 
of PDGF-B protein immunohistochemically and the expression of PDGF-B-mRNA by In 
situ hybridization in the adenocarcinoma cells and macrophages of the lung 
tumors. However, no significant correlation was observed between the degree of 
PDGF-B expression and collagen production in the fibrotic focus.