The Relationship Between DNA and Cancer
DNA is the material present in our cells that makes up our genes. Genes carry the instructions our bodies use to grow and function.
Gene mutations and alterations in cancer development
Throughout life most cells are exposed to various ‘mutagens’. These agents induce changes in the DNA sequence.
- e.g. Tobacco smoke
- e.g. UV from the sun
- e.g. human papillomavirus
Sometimes, mutations arise during the normal cell DNA replication process. Normal healthy cells repair virtually all of these changes. Changes that are not repaired are termed mutations.
When a single cell acquires enough changes (mutations) in the DNA sequence of relevant ‘cancer gene(s)’ it begins to behave in an abnormal way characteristic of cancer.
This cell divides when it should NOT, leading to uncontrolled cell growth that invades local tissue and may ultimately spread throughout the body.
Mutations or alterations can also be inherited from a parent. This means that these cells are more susceptible to acquire enough mutations to become cancer. Less than 10% of gene mutations related to cancer are inherited. Most cancers come from acquired or “somatic” mutations that develop in some cells in a particular organ during one's lifetime.
Two types of genes are particularly important in the development of cancer: proto-oncogenes and tumor-suppressor genes. Proto-oncogenes code for proteins that help cells grow and divide, and tumor-suppressor genes help to stop cell growth when necessary. Often, the mutations that cause cancer are mutations in those genes that regulate cell growth.
Many mutations in these genes have been identified and have been discovered to be associated with one or more types of cancer. Today, researchers are collaborating to identify the catalogue of mutations that can occur in a cancer cell’s genome—all of the somatic alterations to cancer-related genes (genomic changes) present in different cancer types. This will create an invaluable atlas that can be used to better understand all forms of cancer and find new and more effective ways to control this disease.
Treating cancer at the molecular level
The identification of somatic alterations present in cancer is helping guide the development of new therapies focused on targeting and compensating for specific genomic defects. Pharmaceutical companies have already developed therapies that attack only cancer cells and have resulted in unprecedented efficacy in some cancer types. Several of these drugs are in clinical trials focused on patients who are most likely to respond to these specific treatments, based on the changes present in that person’s tumor.
As a result, a new era of personalized care is emerging in which information about the genomic changes specific to your cancer will help you and your doctor determine what treatments are most likely to work for you.