This page has been written by : Radhika Nair
GENETICS OF BREAST CANCER
What are 'genes'?
Our bodies are made up of millions of cells. One of the fundamental properties of cells is to grow and divide. This is what allows a small baby to grow into a fully grown adult. The process of cell division and multiplication is a tightly regulated process. Too much division leads to the formation of a mass of cells which we commonly call a tumor or cancer.
So how does a cell control division? Just the way our brain tells various parts of our body to behave in a particular manner, the cell's brain is stuff called DNA. Portions of DNA code for different attributes like hair color with each functional unit termed a gene. These genes cannot directly lead to the person's hair color being black. This is done by proteins. DNA is like the master controller, RNA is the messenger link which relays the message from the DNA to the proteins which ultimately are the workers and execute the message for example telling the hair cuticle to be black in color.
Phew! That was a lot of introduction to basic biology and is essential for you to understand the basic concept underlying molecular profiling of breast cancer.
How is my breast cancer different than yours?
You are quite different from the person standing next to you in terms of how you look and behave. In a similar manner, breast cancers from different people are quite different. The reason this is important is because these differences allow doctors to classify breast cancers into categories with different treatment options. Tailoring treatment to a specific type of cancer such that it benefits the patient most, with minimal side effects is a corner stone in the concept of personalised medicine.
Two of the most common proteins that are over expressed by breast cancer cells are the Estrogen Receptor (ER) and Her2. Scientists have developed drugs which allow doctors to treat women with Estrogen receptor and Her2 over expressing tumor cells (proteins expressed by the tumor cell) with drugs called Tamoxifen and Herceptin respectively, which specifically target these molecules and stop tumors from growing. For the 70% or more breast cancer patients, treatment with Tamoxifen and Herceptin along with conventional chemo/radiotherapy with surgical options, have meant beating the odds against breast cancer. But for the remainder, especially the basal like breast cancer subtype, we do not have any specific therapy which translates into poor survival for these women.