Application of Petersen Index score for Dukes'B colorectal cancer in a population of 103 consecutive resected patients.

Dukes' B colorectal cancer (CRC) represents a wide spectrum of disease from early penetration through the bowel wall to aggressive and extensive tumours with extramural venous spread and involvement of the serosa, surgical margins or adjacent organs. Among Dukes' B cancers, Petersen Index allows stratification to identify those patients whom chemotherapy may benefit. One hundred and three resected patients with CRC Dukes' B were included prospectively in a database and considered in the present study. According to Petersen Index, a score (from 0 to 4) for each patient was calculated on the basis of peritoneal and margin involvement, venous invasion and tumour perforation. Twenty-four out of 103 tumours were located in the rectum and 79 in the colon. According to PI score 59 patients had a score of 0, 30 of 1 and 14 of ≥2. The overall R0 resection was achieved in 95.1 % of cases and the majority of patients with PI score of ≥2 were R1-2. The mean of harvested lymph nodes was 23.6 (±10.7) with no difference according to the PI score. Patients in the high-risk group had a worse 5-year survival rate (66.3 %) compared with the other group (P < 0.009). Multivariate analysis validated the PI score as a significant independent factor (P = 0.017). Both high-quality pathology and adequate harvested lymph nodes are needed for a proper staging. Even though the influence of PI score on survival is confirmed as it leads to an additional rate of colorectal cancer being considered for adjuvant therapy, we underline that a comparison with additional clinical and histological prognostic factors should be needed.