In the rapidly advancing field of cancer immunotherapy, a new way of looking at tumors has emerged, along with a new vocabulary for classifying and describing them. Read on to learn what the terms “hot” and “cold” mean as applied to solid tumors.
Broadly speaking, cancer immunotherapy is an approach to treating cancer that works to retrain the body’s immune system so that it can better recognize and destroy cancer cells, which are so similar in appearance to healthy tissue that they are usually able to pass through the immune system’s defenses undetected and unchallenged. However, recent research has shown that some types of tumors are more likely than others to be engaged by the immune system.
This is where the new vocabulary comes in. Researchers today talk about “hot” tumors as those with a higher potential for immune infiltration, while “cold” tumors are those with low levels of immune engagement. From a patient's perspective, this generally means that the hotter the tumor, the better. The belief is that the immune system stays engaged after a hot tumor is removed through surgery, so the probability of a relapse is much lower. The idea behind new therapies such as oncolytic viruses is therefore to turn cold tumors into hot ones.
Researchers assess the “temperature” of tumors through a measure called the Immunoscore, which bases results on the density of two different T-cell types in a tumor sample. In at least one study so far conducted by Jerome Galon and his team at the Laboratory of Integrative Cancer Immunology in Paris, the Immunoscore was proven better at predicting the progression of cancer than other standard markers, such as pathological grade or tumor stage. While the study in question focused on colorectal cancer, the researchers believe that the concept should readily extend to other types of solid tumors.
