There is no question that genetics has become a hot topic in medicine. It seems that every week there is an article about a new genetic test, or another person throwing around the term “inherited risk”. These terms can seem scary at first, but with a bit of brushing up, you can use them to your advantage in managing your healthcare.

      To help along the way, Tigerlily is bringing the basics right to your laptop. We’ve partnered with Genomic Health to offer a 5-part blog explaining the ins and outs of breast cancer genetics and genomics. Read on for more information about inherited risk, the different types of tests offered and how they can help with treatment, and more.


The terms “genetics” and “genomics” often go together, but they are not the same.

Genetics looks at the inheritance of certain genes from one generation to the next—specific genes that serve specific functions. (One common example that relates to breast cancer is the BRCA gene, which normally functions to create a protein that fixes changes in the cells’ DNA. When a mutation occurs, this protein may not be produced correctly, affecting its ability to clean up your DNA properly.) The field of genetics focuses on how and whether or not a particular form of a gene has been passed down.

Genomics looks at the interplay between all of an individual’s genes, and studies how the interaction of those genes with each other, as well as with the person’s unique environment, can affect his or her health. While genetics can tell a person whether or not a BRCA mutation has been inherited, genomics can take into account other factors which would reveal a tumor’s predicted response to a particular treatment, or how likely it is to spread.

As a result of advances in both of these fields, the broader field of personalized (or precision) medicine has begun to take shape. Personalized medicine allows a healthcare team to focus on a patient’s own genomic makeup, lifestyle, and the specific genetic makeup of the patient’s tumor cells, in order to develop a treatment plan suited to that patient. Through this approach, they can ensure that the treatment is as targeted as possible. 

There are many applications of genetics and genomics in personalized medicine. For example, a doctor may recommend genetic testing. Genetic testing falls under the umbrella of “genetics”, and can reveal whether or not a person has inherited a specific mutation, for a specific gene—such as BRCA.

A doctor may also use genetic results to determine gene-drug interaction–how a particular patient’s genes will influence his or her response to a given medication.

Finally, a doctor may use tumor sequencing. Tumor sequencing looks at all of the genes within the tumor itself, helping to determine whether a particular course of treatment will work on that tumor. There may be changes in the tumor DNA that will render a particular treatment ineffective; tumor sequencing can help a doctor to know if such changes have taken place and an alternative treatment should be used instead.   


When taking a personalized medicine approach, a doctor may look at the characteristics of the patient’s particular tumor in order to treat it in the most accurate way possible. Some of these characteristics include the size of the tumor, the type of tumor (either non-invasive, meaning it is contained, or invasive), and the grade of the tumor (which refers to how abnormal the cancer cells appear, as well as how quickly they grow). They can also look at more specific characteristics of the tumor, such as hormone receptor status (which tells the doctor whether or not the hormones estrogen or progesterone are stimulating the tumor to grow), and HER-2 receptor status (which tells the doctor whether or not a protein called human epidermal receptor factor is stimulating the tumor to grow). Most likely, they will also take into account any genetic mutations (discussed in our next post), as well as the patient’s lifestyle, which may be exacerbating the risk for breast cancer.

Join us in our next post to find out more about breast cancer screening and genetic testing.