Determination of tumor aggressiveness in colorectal cancer by K-ras-2 analysis.

Markers that predict tumor aggressiveness on a case-by-case basis would enable individualization and optimization of oncologic therapy. To achieve this goal, the presence and specific type of K-ras-2 point mutation was determined from formalin-fixed, paraffin-embedded tissue sites in 247 primary and 166 metastatic-recurrent colorectal adenocarcinomas, using a novel approach consisting of topographic tissue selection, DNA amplification, and direct sequencing applicable to large and needle-biopsy-sized specimens. The results provide the basis for a genotypic classification of colorectal cancer capable of predicting individual tumor aggressiveness, including the pattern and extent of metastasis.