New research, published in the journal Science , has provided the first evidence that the century-old theory that cancer metastases from the primary tumour to nearby lymph nodes, and then to other organs, may not apply in all cases.
A study carried out by a team at Massachusetts General Hospital in the US, showed that for the majority of colorectal cancer patients studied, distant metastases originated directly from the primary tumour without involving the lymph system in the process.
Using a phylogenetic method to reconstruct the evolutionary relationship of primary tumours, lymph node metastases, and distant metastases in 17 patients with colorectal cancer, the authors found that the sequential progression model only applied to a third of the patients. In the other two-thirds, distant metastases and lymph node metastases originated from independent subclones within the primary tumour.
Senior author, Rakesh Jain said the study provides the first direct genetic evidence to explain why complete surgical lymph node removal does not always lead to extended survival. He added that the assay used in the study is safe and effective and could potentially be used in the clinical setting to help guide the management of patients with metastatic cancer.