Prognostic impact of allelic losses in 1p32–36 (HYTM1), 4p15.2 (D4S2397), 5q22.2 (D5S346), 8p22 (D8S254), 18q12.3 (D18S474), and microsatellite instability for colorectal cancer
4132 Background: The aim of this prospective study was to analyse the prognostic impact of allelic losses in the chromosomal regions 1p32–36 (HYTM1), 4p14–16 (D4S2397), 5q22 (D5S346), 8p21–22 (D8S254), 18q12.3 (D18S474) and microsatellite instability (MSI) in colorectal cancer (CRC). The microsatellite markers HYTM1, D4S2397, D8S254, and D18S474 were previously shown to have prognostic relevance in retrospective studies. The National Cancer Institute (NCI) microsatellite panel (BAT25, BAT26, D2S123, D5S346 and D17S250) was used for MSI-Analysis. Methods: Between July 1999 and February 2004, the data from a total of 165 patients, preoperatively diagnosed with colorectal cancer, and operated on in the Department of Surgery, University of Wuerzburg were collected. Inclusion criteria were: (a) electively operated primary adenocarcinomas; (b) obtainment of fresh paired normal mucosa-tumor samples; (c) no postoperative death (survival < 1 month); and (d) availability of follow-up data. Allelic loss (LOH) was determined by comparing the PCR-patterns of tumor DNA with corresponding normal tissue (signal reduction of at least 50%). MSI-L (low microsatellite instability) was defined as one marker out of five NCI-markers, MSI-H (high microsatellite instability) as more than two markers to display microsatellite instability. MSI-H tumours were excluded for further LOH-analysis. The endpoint of the study was tumour specific death. Kaplan-Meier survival curves were compared using the log-rank test. Results: We found expected frequencies in age, gender, tumour stage, and tumour grading. Tumour stage, grading, and an allelic loss of D18S474 was confirmed to be of prognostic significance for UICC I-IV, I-III, and II cancer in univariate analysis. Tumour stage and LOH D18S474 were also independent prognostic variables in stage I-IV and I-III. There was no significant prognostic impact of a loss of the markers HYTM1, D4S2397, D5S346, D8S254, MSI-L and MSI-H in either UICC stage I-IV, I-III, and II colorectal cancer patients. Conclusions: A loss of D18S474 defines a high-risk subgroup of patients with stage I-IV, I-III and stage II colorectal cancers. No significant financial relationships to disclose.