Polymerase chain reaction ( PCR ) showed EGFR amplification in 25 of 77 ( 32 % ) cases and p16 homozygous deletion in 32 of 77 ( 42 % ) cases .
O O O O O O O B-GeneOrGeneProduct O O O O O O O O O O O B-GeneOrGeneProduct O O O O O O O O O O O O