Are immune cells associated with survival in colorectal cancer that has spread to the liver?

This study investigated which types of immune cells are more active in fighting colorectal cancer which has spread to the liver. It was found that T cells are the most active.

It is thought that the immune system response to colorectal cancer (CRC) is an important factor in determining whether the disease progresses or the patient survives. Most evidence relating to this was found in studies of stage 1-3 CRC. However recent findings suggest that the immune system plays an important role in fighting CRC which has spread to the liver (CRC-L).

Usually, immune cells such as T cells are thought to be the most important in determining CRC outcome. However, the liver has a higher number of NK cells (natural killer cells, cells that kill diseased cells) than other cells of the body. It is unclear which cell type is more important in determining CRC-L outcome.

This study aimed to determine whether T cells or NK cells were more active in fighting CRC-L. 21 patients with CRC-L who had liver surgery took part. The number of T cells and NK cells in the tumor and in the unaffected liver cells were calculated. Patients were monitored to measure survival.  

There was a higher level of T cells in the tumor (61.8%) than in the unaffected liver cells (37.4%). In contrast, NK cells made up a smaller proportion of tumor cells (12.9%) than unaffected liver cells (38.3%). In comparison to normal cells, the NK cell number of tumor cells was significantly lower (145 cells/mg) than in normal cells (832 cells/mg).

Overall survival was 43% at 5 years. Patients with a high level of T cells in the tumor had improved 5-year survival (60%) in comparison to patients with a low T cell level (0%). Lower NK cell levels were associated with a higher likeliness of survival.

The authors concluded that T cells are more active than NK cells in fighting CRC-L. It was concluded that the higher the level of T cell activity in the tumor, the higher the likeliness of survival after liver surgery.

If these findings are confirmed by larger-scale studies, they could be used to measure the likeliness of recurrence of cancer post-surgery in patients with CRC-L.  

Consult your doctor if you would like to discuss the role of your immune system in lowering the likeliness of recurrence.