Let’s Get Some Vocab Out of the Way

Targeted therapies are a type of cancer treatment that seek out specific genes and proteins that control how cancer cells grow, divide, and spread. No targeted therapy can be prescribed without first testing for the specific biomarker the therapy would target.

Cancer biomarkers are biological markers produced by the body or tumor in a person with cancer. Biomarker testing helps a clinician identify and characterize important alterations in the tumor. Examples of a biomarker can be unexpected changes in the DNA, RNA, protein, or metabolic profile that are specific to the tumor. These profiles can easily be added to the diagnostic evaluation when a tumor is identified.

How genetic changes affect cancer development is a very active area of research, which has led to improvements in early detection, risk reduction, and the use of targeted therapies. The science is moving quickly, and some acquired gene mutations have become very treatable. In all cases, the key to getting treatment begins with comprehensive biomarker testing and understanding the type of tumor mutation you have.

Inherited Versus Acquired Mutations

A lot of biomarker testing focuses on DNA; specifically, any sort of genetic mutation that may be causing your cancer to grow. There are two basic types of genetic mutations that can lead to cancer. The least common form is an inherited mutation, which accounts for around 5% to 20% of all cancers. These mutations occur in a sperm or egg cell and pass directly from a parent to a child at the time of conception. As a baby develops, the mutation from the initial sperm or egg cell is copied into every cell within the body. Germline testing can reveal important genetic variations that a person was born with using a simple blood or saliva sample.

Acquired mutations are far more common. They occur from damage to genes in a particular cell during a person’s life, replication errors, or sometimes just plain old bad luck. This could occur in a lung or colon cell, which then goes on to divide and form a cancerous tumor. Cancers that are caused by these types of mutations are also called sporadic cancers and cannot be inherited or passed down from parent to child. Factors that cause these mutations include tobacco use, ultraviolet radiation, viruses, age, or sometimes bad luck.

Test to Treat

When it comes to acquired mutations, the type of mutation you have is important to understand as it influences what targeted therapies are available to you. New treatments have recently become available for mutations in genes encoding the cytoplasmic and mitochondrial forms of isocitrate dehydrogenase. Known as IDH mutations, IDH1 and IDH2 are frequently detected in cancers of various origins, including 20% of acute myeloid leukemia and cholangiocarcinoma, and 50% to 80% of chondrosarcoma (CHSs) and gliomas. These cancers affect the blood, liver, bones, cartilage, and brain. 

Mutations in IDH genes prevent cells from differentiating and in some cases, the cancer cells begin to grow out of control. It is important to note that IDH mutations don’t indicate the severity of the cancer, nor the likelihood of a good or bad prognostic outcome. The mutation is neutral in its significance to the overall course of the disease. However, it is helpful information in that it can guide you toward a treatment that targets that specific mutation.