Cancer Genetics

DNA sequencing has changed the way we are preventing and treating caner. All cancers occur due to abnormalities in the DNA sequence. Some mutations are hereditary, most are sporadic. So far we have identified a couple genes that are associated with cancer, and are working to discover more. The ability to sequence a patients whole genome is being utilized in many different ways and helping the development of new personalized treatments for cancer.

Detection

Discovering the mutations in genes that result in cancer is an important step in understanding and curing caner. The Cancer Genome Atlas is an organization that is attempting to map the genetic changes in 20 cancers. As said in the Cancer Genome Atlas home page, cancer is a disease of the genome and as more is learned about cancer tumors, the more we are finding that each tumor has its own set of genetic changes. Understanding the genetic changes that are in cancer cells is leading to more effective treatment strategies that are tailored to the genetic profile of each patient’s cancer. (82) Click on the logo above for a link to their home page, to learn more about the Cancer Genome Atlas.

The Breast Cancer Genes

While researchers are on a mission to map more of the genetic variations that are linked to cancer, some have already been found. In 1994 scientist discovered the BRCA1 gene located on chromosome 17. A year later, BRCA2 was discovered. (83) These genes belong to a class known as tumor suppressors. Mutations in these genes have been linked to hereditary breast and ovarian cancer. (84) DNA sequencing allows for women to test and see if they inherited this mutation, which allows for early detection and early treatment.

Figure on right (84) Mutations in the genes BRCA1 and BRCA2 means an increased risk of developing breast cancer or ovarian cancer

CGEMS

In 2005 the Cancer Genetic Markers of Susceptibility project was launched. The goal of the project is to identify common inherited genetic variations associated with risk for breast and prostate cancer. (85) Click on the image for a link to the home page, to learn more about CGEMS.

New Treatments

As the DNA sequencing technology advances, there is no shortage of the information being discovered about genetics and disease. Applying all this into treatments is a little bit of a slower process, however some researchers have found very useful ways to use the technology.

In 2010, researchers at John Hopkins University developed a blood test based on the DNA of tumors that could help shape treatment for individual cancer patients. They sequenced the DNA of the actual tumor tissue looking not for tiny DNA changes but rearrangements in big areas of the tumor cell's genome. The DNA of the tumor cells vary greatly from the DNA of the normal tissue. The cancer cell's DNA can be used as a "fingerprint" of the cancer. The research suggest that by testing the blood of a patient for this "fingerprint", doctors will be able to tell whether a patient being treated is free of the disease or needs additional or more aggressive care. (86) According to an article written on the study, "The report represents one of the most tangible examples yet of how the ability to sequence a person's entire genetic code could have a direct impact on patient care." (86) With the rapid and cheap DNA sequencing technologies, scanning the DNA in the blood stream to detect any presence of mutated cancer DNA could be a very effective way of monitoring a patients condition.

A Bit of Ethics and Legal Issues

A topic of high interest to cancer researcher, patients, a pharmacologists, is the ability to patent genes. In 2009, the American Civil Liberties Union filed a law suit against Myriad Genetics Inc. for patenting the BRCA gene. The question on whether it should be legal to patent genes was taken all the way to the supreme court. March 26, 2012 the court decided that it was not legal to patent genes. Click on the image below to learn more.

The percentage of how often Breast Cancer is Hereditary (87)

Targeted Cancer Therapies

Targeted Cancer Therapy is a fairly new type of cancer therapy where drugs or other substances stop the growth of cancer cells by inhibiting specific molecules that are involved with the tumor progression (81) To develop the drug, scientist sequence the whole genome, find the mutation of a particular gene which causes the tumor cells to no longer be suppressed, and then design a drug that targets the defective protein coded by that gene. Many of these therapies has been approved by the FDA, and more still are undergoing clinical trials. For more information on targeted cancer therapies, click on the link below.