Colorectal cancer is the third most common cancer type worldwide with >50% of the patients succumbing from the disease.
Complete resection of the primary tumor and regional lymph nodes is the most important intervention in the treatment of colorectal cancer, and 70-90% of all colorectal cancer patients may undergo surgical resection. Evaluation of the resected specimen is an essential step in identifying prognostic factors in predicting disease recurrence. The American Joint Committee on Cancer (AJCC) and International Union Against Cancer (UICC) have introduced the tumor-node-metastasis (TNM) staging system, which assesses primary tumor (T), lymph node metastasis (N), and distant metastasis (M) to predict disease recurrence and survival.
Lymph nodes are key elements of the TNM staging system, and presence or absence of disseminated tumor cells is a highly significant factor in predicting disease-free survival and overall survival in patients with colorectal cancer without distant metastasis. The lymph node status is also a crucial factor in deciding on adjuvant chemotherapy after surgical resection. Although the underlying mechanism is not clear, it is suggested that tumor cells spread from the primary tumor site to the lymph nodes via lymphatic vessels and then on to the next distant organ. Therefore, regional lymph node metastasis is believed to be an essential step in tumor cell dissemination in colorectal cancer.
In the TNM staging system, lymph node status, pN-stage, has the highest prognostic value. Still patients with tumor spread to regional lymph nodes are missed by the routine method, histopathology. Attempts have been made to improve the prognostic value of metastatic lymph nodes, e.g. lymph node ratio, proximal lymph node distribution, as well as periglandular growth. However, these procedures have so far not been very successful.
Improving the technique for finding tumor cells in lymph nodes will have a direct impact on TNM-staging, whether used on its own or in conjunction with routine histopathology or any of the additional procedures mentioned above. ColoNode®, which accurately determines relevant biomarker mRNA levels, is likely to significantly improve pN-staging in colorectal cancer thereby saving patients’ life.