Personalized medicine involves selecting treatments based on a person’s unique genetic makeup and the genetic makeup of the tumor. The promise of personalized medicine is that prevention, screening, and treatment strategies can be developed that are more effective and cause fewer side effects. By performing more genetic tests and analysis, doctors may customize treatment to each patient’s needs.

Steps involved in creating a personalized cancer screening and treatment plan include:

• Determining the chances that a person will develop cancer and selecting screening strategies to lower the risk
  
  
• Matching patients with treatments that are more likely to be effective and cause fewer side effects
  
  
• Predicting the risk of recurrence (return of cancer)

Why personalized medicine is different

Cancer begins when normal cells begin to change and grow uncontrollably, forming a mass of cells called a tumor. In a cancer cell, genes mutate (change) in ways that are harmful.

Typically, a person with cancer receives a treatment based on the type and stage of the cancer, such as stage III colon cancer. For example, people with this type of cancer usually receive surgery followed by chemotherapy. This is commonly called the “one size fits all” approach. However, some cancers respond to these treatments while others do not, and some people have significant side effects caused by treatment, while others do not. Researchers think that genetic differences are responsible for these results, and they are more closely studying the genetics of people with cancer and their tumors to develop treatments to target altered genes responsible for the growth and spread of cancer. People with cancer may still receive standard treatments as part of their treatment plan, but many are now being offered forms of personalized cancer treatments, such as a targeted treatment, that are matched with patients based on genetic characteristics. Personalized cancer treatments may be offered as an active part of the treatment plan or as part of a clinical trial (research studies in people). Learn more about clinical trials.

Examples of personalized medicine

Some examples of personalized medicine strategies for cancer include:

Targeted treatments. A targeted treatment is designed to block a specific gene or protein that has a critical role in the survival, growth, or spread of a specific cancer cell. The epidermal growth factor receptor (EGFR) is one of these targeted areas. In a healthy cell, EGFR receptors allow cells to grow and divide. When there are too many receptors, as happens in cancer, the cancer cells continue to grow and divide. In colorectal cancer that has spread to other parts of the body, the EGFR transmits signals and stimulates cancer cells to reproduce and spread. Some types of chemotherapy, such as panitumumab (Vectibix) and cetuximab (Erbitux), bind to EGFR and stop the signals from being transmitted, which in turn slows or stops the growth of the cancer. In tumors that test positive for a mutation in a gene called the KRAS (pronounced kay-rass) gene, the tumors don’t respond to the drugs because signaling still takes place. By testing for this gene mutation, doctors can avoid giving patients with KRAS mutations these drugs. This testing reduces unnecessary treatments. Read about the American Society of Clinical Oncology’s (ASCO's) recommendation for KRAS testing in people with colorectal cancer and learn more about targeted treatments.

Pharmacogenomics. Pharmacogenomics is the study of how inherited differences in genes that activate or break down drugs can lead to differences in the effectiveness of the drug or the side effects it may cause. For example, some people’s bodies may process a medication quicker than others, so that person would require a higher dose of that drug for it to be effective. However, if someone’s body does not process a medication as quickly, the medication will stay in the bloodstream for a longer time and may cause more severe side effects.

How can pharmacogenomics be put into practice for cancer treatments? Here’s an example: People with colorectal cancer that have a specific gene variation may have life-threatening side effects when treated with irinotecan (Camptosar). This altered gene makes it harder for the body to break down irinotecan. In these patients, doctors prescribe lower amounts of irinotecan so patients will not have any side effects. Read more about pharmacogenomics.

Disadvantages

Despite the promises of personalized cancer treatments, there are some disadvantages to consider. Not all types of cancer have personalized treatment options. Some personalized cancer treatments are only available through a clinical trial and are not yet standard treatment options. Genetic testing of both the patient and the tumor sample may be costly and time-consuming, and many insurance plans may not cover the costs of these tests. Some personalized treatments, such as targeted treatments, can also be expensive.

Questions for the doctor

To learn more about personalized cancer care, consider asking your doctor the following questions:

• What are my treatment options?
  
  
• What clinical trials are open to me?
  
  
• Are there genetic tests available that can help guide treatment choices?
  
  
• Is this treatment considered an example of personalized medicine? If so, how?
  
  
• What are the benefits to this treatment?
  
  
• What are the potential side effects of this treatment?
  
  
• What is my prognosis?

What this means for patients

Personalized medicine is a new and exciting approach to cancer treatment, yet one that has much room to grow. There is much that doctors still don’t know about the genetic makeup of cancer and how cancer treatments work. Today, researchers are developing more cost-effective, efficient ways of performing genetic tests that are leading to new treatments to target genes responsible for the growth and spread of cancer. Advances in personalized medicine may lead to more effective cancer treatments and treatments with fewer side effects. Talk with your doctor to learn more about personalized cancer treatments and whether any may be a part of your treatment plan.

More Information

Cancer Advances: Personalized Cancer Medicine: Translating Breakthroughs in Biology into Better Treatment for Patients

ASCO Annual Meetings—Cancer News for Patients

Last Updated: May 18, 2009