P53 AND THYMIDYLATE SYNTHASE EXPRESSION IN UNTREATED STAGE-II COLON-CANCER - ASSOCIATIONS WITH RECURRENCE, SURVIVAL, AND SITE

We initiated a retrospective study to determine whether p53 status and thymidylate synthase (TS) protein expression in primary colon tumors influence recurrence and survival for patients with stage II colon can cer. Tumor specimens from 45 consecutive untreated patients with stage II colon cancer were examined for p53 and TS protein expression using immunohistochemistry. The median follow-up was 5.1 years. Eighteen pa tients had left-sided tumors, and 27 had right-sided tumors. Fourteen of 45 patients (31%) developed recurrence. p53 overexpression was dete cted in the tumors of 18 patients (40%); 10 patients (55%) with p53 ov erexpression recurred; and 4 of 27 (15%) without evidence of p53 overe xpression recurred (P = 0.002), High TS expression was detected in the tumors of 16 patients (36%): 8 patients (50%) with high TS expression recurred, and 6 patients (21%) with low TS expression recurred (P = 0 .027), Patients with p53 overexpression had a significantly poorer sur vival than did those patients without p53 overexpression (P < 0.001). High TS expression was associated with poor survival (P = 0.004), p53 overexpression and high TS expression were significantly associated wi th left-sided tumors (P = 0.003 and P = 0.022), Thirteen of 16 patient s (81%) with high TS expression also overexpressed p53, and 24 of 29 p atients (81%) with low TS expression did not manifest p53 overexpressi on (P < 0.001), p53 and TS expression in primary stage LI colon cancer are associated and appear to influence recurrence and survival. In th is pilot study, left-sided tumors demonstrate significantly more p53 o verexpression and significantly higher TS expression than do right-sid ed tumors, which may explain the significantly poorer survival for pat ients with left-sided tumors.