Humoral immune response to p53 correlates with clinical course in colorectal cancer patients during adjuvant chemotherapy

Background and aims: Overexpression of p53 protein in malignancies induces an immune response in some cancer patients. We investigated whether production of serum antibodies against p53 (p53-Ab) is associated with pathohistological parameters of colorectal carcinoma and whether p53-Ab can serve as a tumor marker during cancer treatment. Patients and methods: Serum samples from 220 colorectal cancer patients during surgery and adjuvant chemotherapy and 42 healthy controls were tested for the presence of p53-Ab by ELISA. Expression of p53 protein in tumors was determined using mouse anti-human p53-Ab. Results: Serum p53-Ab were detected in 18% of patients while all controls were negative. A strong correlation between p53-Ab production and p53 protein expression was observed: 70% of p53-Ab positive cases had tumors positive for p53 vs. 52% of p53-Ab negative cases. There was also a significant predominance of p53-Ab positive cases in Dukes' stages B and C over stage A. Although surgery alone reduced p53-Ab levels, decreases in p53-Ab titer became significant midterm through chemotherapy compared to both pre- and postoperative values and remained decreased until the completion of treatment. Conclusion: The presence of p53-Ab in sera of patients with colorectal cancer indicates tumors in more advanced histopathologic stages (Dukes' B, C). Due to low sensitivity (18%) p53-Ab are not recommendable as a preoperative marker for colorectal cancer. However, due to high specificity (100%), their monitoring after surgery and adjuvant chemotherapy has potential for early diagnosis of tumor relapse in p53-Ab positive cases.