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Genomics and Cancer Treatment

  • Testing that evaluates the entire genome for mutations associated with certain cancers
  • For people who may benefit from personalized medicine to treat their condition
  • Next steps include determining the best treatment and monitoring response with further lab testing
  • Involves Pathology, Internal Medicine, Yale Cancer Center


By quickly and inexpensively sequencing an individual's entire genome, pathologists can identify mutations that cause particular types of cancer. This information helps doctors create custom treatments. This new capability is sometimes called precision medicine or personalized medicine. It has given rise to a new discipline within the medical field, genomic pathology—an area where Yale Medicine has exceptional expertise.

What is genomic pathology?

Genomic pathology focuses on understanding the basic genetic and molecular underpinnings of disease, says Yale Medicine pathologist Janina A. Longtine, MD. 

“This knowledge underlies tests within pathology that can impact patient care and make our classification of disease and the treatment plan more precise,” she says.

Genetic sequencing can now be done for all types of cancer, says Dr. Longtine, who directs the Molecular Diagnostics Laboratory, at Yale Medicine.

What do genomic pathologists actually do?

Genomic pathologists perform genetic sequencing studies on tissue samples taken via a biopsy. They are looking for information that can be used to attack the disease with treatments at the molecular level.

“We use multiple types of technology to look at DNA,” says Dr. Longtine. “We now have the ability to understand broad changes of how multiple genes can cause disease—not just one.”

“We have evolved from the study of single genes to being able to look at multiple ones and understand the interplay. We sift through and refine that information to understand disease and improve its classification and treatment.”

All of this sounds very technical, but Dr. Longtine says: “We are very cognizant of the patient. We’re thinking of our colleagues in the clinic the entire time. Our goal is to make sure we communicate well in our reporting of results so that they understand the implications of the testing.”

What tests do genomic pathologists perform?

Lab techniques are used to extract DNA from a cancer tissue sample. The DNA is mixed with reagents and placed in a sequencing machine for processing.

Dr. Longtine says this process produces “raw-sequencing data pieces from each gene that we are interested in looking at.”

Comparing this DNA sequence data with that belonging to a normal human genome highlights any abnormalities in the patient’s cancer.

“We are looking for mutations that distinguish these genes from normal ones and also from common variations that are present in the population but are known to be benign,” Dr. Longtine says.

How do genomic pathologists influence a specific patient’s diagnosis?

The majority of gene-sequencing tests today are done to pin down a precise diagnosis for cancer in order to identify the most effective treatment, says Dr. Longtine.

“We also use these technologies to monitor response to treatment,” she says. “And we can also determine genetic risk factors at multiple levels with this type of test as well.”

The field of genomic pathology is still in its early days. “Right now, we’re in something of an in-between stage where we get a lot of information that we don’t need, or we don’t know what we can do with it,” Dr. Longtine says. “The more we learn, the more we need to learn.”

But there are new opportunities to apply the information obtained from these studies to improve patient care.

“We’re continually improving our ability to design and optimize  and interpret and communicate these results based on our medical and scientific expertise,” Dr. Longtine says. “We see our role as working closely with our clinicians to serve as the conduit between technology and patient care.”

What makes Yale Medicine's approach to genomic pathology unique?

Yale Medicine has a dual focus when it comes to genomics and molecular pathology, says Dr. Longtine. 

“We want to be at the forefront, innovating and developing and using cutting-edge science, but we don’t do things just because they are flashy,” she says. “We want to be sure that we are providing information that is useful, has been sufficiently studied, and has clinical implications.”

“We have people here who do important research, who are at the top of their field and have published lots of papers," she says. "But we don’t do anything involving patients without feeling comfortable that the science is tested and true. That interplay makes for a dynamic, patient-centered focus that keeps us on our toes.”