Imunoexpression of Ki-67 and p53 in rectal cancer tissue after treatment with neoadjuvant chemoradiation

Adjuvant or neoadjuvant chemoradiotherapy (CRT) increases the survival rates significantly, but it also increases morbidity. Molecular markers may help on prognosis evaluation and treatment choice.

The purpose of this study is to evaluate the imunoexpression of p53 and Ki-67 in rectal cancer tissue after CRT treatment.

Stage II or III rectal cancer patients were evaluated and treated with RT and 5-FU preoperatively (neoadjuvant treatment, NG) or after surgical resection of the cancer (adjuvant treatment, AG).

Thirty-one patients were enrolled in the NG and 30 in the AG; 63.95% were between 50 and 70 years, 50.8% were male, and 53% were in stage III. Of the tumors, 64.5% of the NG and 63.34% of the AG had not overexpressed p53 (p = 0.865) and 9.67% of NG and 33.33% of the AG tumors had a high proliferative index (HPI) of Ki67, p = 0.052. We have not found any difference among metastasis development in the groups (p = 0.708). After 5 years, patients with low proliferative index (LPI) of Ki67 tumors had the best survival rate (p = 0.041). Patients with positive or negative p53 tumors had similar survival (p = 0.35). Patients with HPI of Ki67 had an increased marginal risk for death (p = 0.069).

The rate of tumors that overexpressed p53 was similar in both groups. Patients with p53 positive tumors survived as long as those with p53 negative. Patients treated with chemoradiotherapy before surgical resection, expressed Ki67 in a small percentage. Rectal cancer patients with LPI of Ki67 had the best prognosis.