P53 accumulation, deoxyribonucleic acid ploidy and progression of bladder cancer

The alterations in deoxyribonucleic acid (DNA) ploidy and p53 expression during progression of bladder cancer were determined.

p53 Expression and DNA ploidy were studied in 51 patients with transitional cell carcinoma of the bladder (mean followup 5 years). Of 29 primarily superficial tumors (stages Ta and T1) 17 became subsequently invasive (greater than stage T2) within an average of 4 years (group 2) and 12 recurred superficially with no sign of progression during a mean followup of 10.8 years (group 1). Of the patients 22 had metastatic disease (group 3). Samples of tumors at diagnosis and recurrence or progression were analyzed by immunohistochemistry and flow cytometry.

p53 Accumulation was detected at diagnosis in 29 of the 51 patients (57%), including 3 of 12 (25%) in group 1, 5 of 17 (29%) in group 2 and 14 of 22 (64%) in group 3. The p values for the differences between groups 1 and 3, and 2 and 3 were 0.07 and 0.054, respectively. Abnormal DNA contents were noted in 3 of 12 (25%), 11 of 17 (65%) and 16 of 22 (73%) patients in groups 1 to 3, respectively, and the differences between groups 1 and 2, and 1 and 3 were statistically significant. Using these 2 genetic markers, we found genetic progression to be uncommon in groups 1 and 3, whereas in group 2 an initially negative p53 staining became positive at invasion into the muscle in 5 of 12 patients (42%).

The tumors in patients with superficial recurrences are mostly diploid and negative for p53, and those with metastasis are nondiploid and positive for p53 from the beginning, while further genetic progression is uncommon. However, p53 tends to accumulate frequently when the tumor begins to invade the muscle. There seems to be a need for caution against under staging an apparent stage T1 tumor that is positive for p53.