September 27, 2017

A genetic approach to cancer treatment

By Sharon Rosen

Article by Kristin Clift

The medical community has historically defined and treated cancer based on where it is found in the body, such as the breast, lung or colon. So what has changed?  The FDA has recently started to approve treatments based on the genetic makeup of cancer rather than where the cancer is located.

This allows us to approach cancer treatment in more general ways. That means if a drug is approved for a specific genetic marker, it could potentially be used for breast, colon or prostate cancer – if the genetic mutations in each type of cancer are similar.

Why this is an option

Sequencing a patient’s DNA continues to become faster and cheaper. More patients now have a window into their genetic codes to better understand how changes in their genes can lead to diseases like cancer.

Alexander Parker Ph.D., associate director, Mayo Clinic Center of Individualized Medicine, explains how genomics has changed the way physicians and scientists approach cancer treatment.

Alexander Parker, Ph.D.

“The ability to quickly and cost-effectively explore the molecular depths of cancer with genomic testing has served to underscore something that we’ve known for a long time. That is, cancer isn’t a disease of a specific organ; it’s a disease of your DNA.” says Dr. Parker.

Sequencing helps us to understand if a genetic mutation in, say, breast cancer is similar to a genetic mutation linked to colon cancer. If that is the case, a patient with this type of breast cancer may benefit from a treatment used for colon cancer, rather than one used to treat breast cancer.

Shifting to an individualized approach

Historically, physicians treated all cancers that arise in the same organ the same way. For example, if you have kidney cancer, you are treated with certain drugs, and if you have lung cancer, you are treated with different drugs – even if these two different cancers are similar on a molecular and genetic level. With this approach, the organ where the cancer originates defines the treatment.

As Dr. Parker explains, “This view of cancer would be similar to a mechanic who treated car problems based on the make and model of a car rather than looking under the hood to see what was going on.”

Genomic technology is allowing us to shift our focus from the organ where the cancer originates to the genetic characteristics of the cancer tumor, leading to the development of new diagnostic tests and targeted treatments.

“We are getting closer to the day when patients can say to their physicians, ‘Don’t tell me how you treat breast cancer. Tell me how you’ll treat the cancer that is in my breast,” says Dr. Parker.

Overcoming challenges to access individualized therapies

Genomic technology offers many promising discoveries, but we have also encountered challenges that include:

  • Difficulty accessing medications for “off label” use: Even after a patient’s tumor has been sequenced and genetic changes have been identified, physicians may have difficulty obtaining a targeted therapy if that medication has not been approved to treat the patient’s particular type of cancer.
  • Targeted therapies are often only used after standard therapy fails: Physicians use approved standard therapies first when treating a cancer patient and only turn to therapies that target a specific genetic mutation in a tumor if standard therapy fails.

However, with the push towards more individualized medicine and the FDA’s recent shift, we’re making an improvement on how we view and treat cancers. More and more treatments are getting approved for any cancer with a particular genetic profile rather than an organ-defined cancer.

At Mayo Clinic Center for Individualized Medicine, we are developing and offering more tests to genetically identify cancers in order to provide the best treatment options for our patients.

As Dr. Parker explains, “These tests offer our patients, especially those who have not benefitted from standard therapies, a more targeted therapy to treat their specific type of cancer. As technology advances, we hope to offer tests that examine a broader group of genes that may impact disease and develop more targeted treatments for patients.”

Dr. Parker is also co-leader of the Genetic Epidemiology and Risk Assessment Program in the Mayo Clinic Cancer Center.

Register for the 2017 Individualizing Medicine Conference

Learn more about precision medicine and how it can be applied to improve diagnosis and treatment for many conditions, including cancer, at Individualizing Medicine 2017: Advancing Care Through Genomics.

The Mayo Clinic Center for Individualized Medicine, is hosting the sixth annual genomics conference, October 9–10, in Rochester, Minnesota.

Mayo Clinic Center for Individualized Medicine is hosting the conference with support from the Jackson Family Foundation.




Tags: #cancer treatment, #CIMCon17, #DNA analysis, #Genetic Epidemiology and Risk Assessment Program, #Individualizing Medicine 2017, #targeted therapies, Advanced Cancer, cancer, center for individualized medicine, DNA Sequencing, Dr. Alexander Parker, Genetic Testing, Genomic Sequencing, genomics, medical research, Precision Medicine

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