Introduction
If a gene becomes damaged, this damage is called a mutation. Mutations can cause the gene to not work how it should and cells can grow out of control. When cells grow too quickly or uncontrollably, cancer forms. Things like smoking or the environment may cause these mutations, or they may be inherited. If we could fix these mutations, we could stop cancer from starting.

Gene therapy
Gene therapy modifies a person’s genetic information to treat disease. The treatment uses a carrier, called a “vector,” to deliver new genetic material to a diseased gene. Viruses are the most common vectors because they are uniquely capable of infecting cells and transferring genes. The viruses are disarmed and therefore not harmful but do carry low risks. Recently, researchers have discovered how to use microscopic particles for delivery, instead of the viral vectors, which eliminates risks associated with the use of the virus.
Depending on the cancer and the type of therapy, the vector can be injected or introduced intravenously into the patient’s tissue, or a sample of the patient’s cells can be removed and exposed to the vector in a lab before being returned.

The goal of gene therapy
Gene therapies bring potential benefits.
1- Treatments are more precise than chemotherapy or radiation.
2- Gene therapies can be used in combination with other cancer treatments to enhance their effectiveness.
3- Patients do not have to undergo surgery.
4- They provide new opportunities for patients with rare cancers that don’t respond to other types of treatment.
5- There is a reduced chance of relapse as the modified cells remain in the body long-term and can identify and attack cancerous cells for many years.

Can gene therapy be combined with other treatments?
Yes, gene therapy can be combined with other forms of cancer treatment, including surgery, radiation and chemotherapy.

The ways to use gene therapy
Researchers are testing ways to use gene therapy to treat cancer. Gene therapy may be used to:
1- Replace missing or non-working genes. For example, p53 is a gene called a "tumor suppressor gene." Tumor suppressor genes prevent or stop tumors from forming. Cells that are missing this gene or have a non-working copy because of a mutation, may be "fixed" by adding working copies of p53 to the cell.
2- Stop certain genes that can cause new cancer or the spread of an existing cancer (called “metastasis”). These genes are called “Oncogenes.” By stopping these genes, the cancer and/or its spread may be stopped.
3- Use the body's own immune system by putting genes into cancer cells that trigger the body to attack the cancer cells as foreign invaders.
4- Put genes into cancer cells so that chemotherapy, radiation therapy, or hormone therapies can attack the cancer cells more easily.
5- Create "suicide genes" that can enter cancer cells and cause them to die off.
6- Prevent new blood vessels from growing within the tumor. Cancers need a blood supply to grow and survive. By stopping the blood supply, the cancer slows or stops growing (called “anti-angiogenesis”).
7- Use genes to protect healthy cells from the side effects of therapy, allowing higher doses of chemotherapy and radiation to be given.

The side effects of gene therapy
Gene therapy is a newer treatment option for cancer. At this time, we do not know all the side effects it may have, especially long-term side effects that may happen years after receiving this therapy. After receiving gene therapy, the patient's immune system may react to the foreign vector. Symptoms of a reaction may be a fever, severe chills (called rigors), a drop in blood pressure, nausea, vomiting, and headache. These symptoms often get better within 24 to 48 hours of receiving the treatment. Other side effects depend on the type of vector used and how it is given. For example, if the gene is given into a patient's lung, the side effects may affect the lung.
Some side effects are “theoretical,” meaning that it is possible that they could happen, but they have not actually happened in clinical trials yet. There is a fear that the genes could enter healthy cells and damage them, which could lead to another disease or another cancer. If genes enter reproductive cells, they could damage sperm or eggs. It is feared that this damage could then be passed on to future generations. At this time, researchers are very careful to watch for these unwanted side effects and perform tests in animal studies before the therapy is given to humans.
Talk with your care team about whether gene therapy is part of your treatment plan and if there any specific side effects that you should be aware of.



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