Objectives: Radiation therapy (RT) effect on p53 and p21 proteins after 27 Gy was analyzed.
Methods: A total of 80 biopsy specimens obtained from 40 patients with squamous cell carcinoma of the uterine cervix before RT and after 27 Gy of RT was investigated for combined p53 and p21 expression.
Results: Cancer cells and degenerated or swollen cancer cells caused by 27 Gy that were positive for p53 and p21 showed intranuclear reactivity. Cancer cells at 27 Gy showed stronger p53 positivity than intact cancer cells before RT. The mean p53-labeling index was significantly increased at 27 Gy (P = 0.005). Patients with more or less than 10% of labeling indexes were defined as positive (+) or negative (-), respectively. Four staining patterns of combined p53 and p21 staining were observed: p53(-)p21(-), p53(-)p21(+), p53(+)p21(-) and p53(+)p21(+). Of 40 patients, only three showed the p53(+)p21(-) pattern before RT and 13 showed p53(+)p21(-) pattern after 27 Gy. There was a significantly different distribution of the p53(+)p21(-) patients before RT and after 27 Gy (P = 0.012). These four staining patterns were not correlated with either 5-year survival rate or local control rate.
Conclusion: These results may suggest that (1) 27 Gy induces degeneration and necrosis of cancer cells and enhances p53 accumulation in cancer cells, and (2) a significant increase of p53(+)p21(-) patients is observed of RT.