CEA TISSUE-STAINING IN COLORECTAL-CANCER PATIENTS - CORRELATION WITH PLASMA CEA, HISTOLOGY AND STAGING

To study the expression of tissue carcinoembryonic antigen (CEA) by im munoperoxidase staining in colorectal adenocarcinomas and its relation with preoperative serum CEA and clinicopathological parameters, we st udied 85 unselected patients who underwent resective surgery for color ectal adenocarcinomas and were followed up for a mean of 66 mths. All tumors except 2 showed positive staining for CEA. The staining pattern was classifiable into 4 types: apical, cytoplasmic, basolateral and s tromal, according to the predominant sites of staining. We found a sig nificant positive correlation between tissue CEA staining pattern and preoperative plasma CEA. Plasma CEA levels were higher when tumor cell staining extended to basolateral regions of the cells and into stroma l tissues rather than restricted to apical and cytoplasmic regions (p = 0.012). Furthermore, tissue CEA staining also correlated positively with vascular invasion by tumor cells (p = 0.046), with basolateral an d stromal types associated with more frequent vascular invasion than a pical and cytoplasmic types. This was in contrast to the preoperative CEA which did not correlate with vascular permeation. We speculate tha t tissue CEA staining is useful in indicating possible vascular invasi on even at early stage whereas vascular invasion by a larger tumor bul k or even tumor metastases may be necessary to produce an increased pl asma CEA level that is detectable. On the other hand, preoperative pla sma CEA had a strong, positive relationship with tumor stage and morta lity (p < 0.001 for both). Preoperative CEA was higher in tumors showi ng moderate and poor differentiation, although it did not reach statis tical significance (p = 0.068), whereas tissue CEA staining had no cor relation with tumor differention. Although tissue CEA staining pattern s appear useful in explaining some pathophysiological events, it offer s little additional information to plasma CEA in management of patient s with colorectal carcinoma.