Figure 2.

Colorectal cancer progression model with typical morphological and chromosomal changes. Typical chromosomal imbalances associated with lymph node and liver metastasis formation are represented, DNA gains are shown in red; DNA losses in green. The two arrows indicate that lymphatic and hematogenous tumor spread may occur independently of each other, although there are alterations common for both dissemination pathways (e.g., deletions on 8p and 21q21). Additionally, there are characteristic morphologic features. Liver metastases typically show a kribriform solid tumor growth with pronounced apoptosis and necrosis with only little stroma, a pattern frequently detectable already in the primary tumor corresponding to a poorly differentiated carcinoma (G3, high-grade). In contrast, lymph node metastasis and nonmetastasizing primary tumors often show a predominant tubular differentiation with a strong desmoplastic stroma reaction and are thus classified as low-grade carcinomas (G1 and G2).