Lymphocyte count reduction is associated with better rectal cancer outcomes

This study investigated the relationship between lymphocyte (a type of white blood cells) counts and treatment outcomes for patients with rectal cancer. Researchers suggested that lymphocyte count reduction may be caused by rectal cancer treatment and is associated with better tumor response.

Colorectal cancer is the third most common cancer worldwide. Chemotherapy and radiation therapy are commonly recommended before surgery. This treatment reduces the risk of cancer coming back. 

Chemotherapy and radiation therapy are used to kill cancer cells and stop the tumor from growing. However, it was showed recently that these treatments may cause an immune response. The immune system becomes active and attacks cancer cells. Prior studies showed that immune cells such as T lymphocytes, when found in and around the tumor may improve patient survival.

On the other hand, lower blood lymphocyte count was associated with a shorter overall survival and with side effects due to radiation therapy. It is not known how these treatments affect the immune cells located in the circulating blood.

This study included information about 371 patients with rectal cancer. These patients received chemotherapy with and without radiation therapy before surgery. Blood counts were measured before the treatment and before rectal surgery.

Circulating lymphocyte count decreased after therapy. This change was associated with tumor shrinkage. The average total lymphocyte reduction in the chemotherapy-only group was 14.29%. This reduction was 52.14% in the chemotherapy and radiation group. The total lymphocyte count reduction in the chemotherapy-only group was lower when compared to the radiation group. This may be due to the effect of the radiation on cancer cells.

Total lymphocyte count reduction was greater in the group with a good response (39.8%) compared to the group with a poor response (33.31%). Patients with a total lymphocyte reduction had a 2 times higher chance of tumor shrinkage.

This study concluded that circulating lymphocyte count decreases during therapy before surgery and it is associated with better tumor response. This may happen due to the immune response caused by the treatment.