The following post, about personalizing your breast cancer treatment, is by John Link, M.D.
Did you know that “breast cancer” is not a simple disease, but is comprised of four distinct types?
I outline the most important differences between these types of breast cancer below. You can learn even more about these varieties by
In that video I mention “Agendia.” I’m referring to a company that makes genomic tests for breast cancer patients called MammaPrint® and BluePrint™. These are the most advanced tests of their kind, and I urge all early-stage breast cancer patients to take them. They will tell you which form of breast cancer you have so you and your doctor can select treatment options that are tailored to curb it, because your treatment should fit the specific characteristics of your tumor.
Some tumors require more aggressive treatment because they are fast-growing and likely to spread. Others are almost always curable with relatively moderate treatment because they don’t threaten to grow quickly or spread.
Recently, a new system to classify these cancers has emerged. These classifications help you and your physician understand the aggressiveness and likely outcome of your particular breast cancer, so you can together choose the treatment options that fit it best. For instance, if your cancer is one of the least aggressive forms and is unlikely to recur (that is, come back after treatment), you can safely avoid chemotherapy and all the upsetting, potentially toxic side-effects that can accompany it.
The new classification system was made possible by genomic tests. These are different from the genetic tests you may have read about with the Angelina Jolie story. Genomic tests allow researchers to better understand the different genetic mutations that separate one type of breast cancer from another. The classification system is known in the medical field as molecular subtyping.
These tests also are the best way to find out if you can safely avoid chemotherapy and still have an excellent outcome. You can find out more about the tests, which are part of what is called personalized medicine, here.
So, the four basic types of breast cancer are as follows, in increasing order of aggressiveness:
Luminal A: This is the least aggressive, least dangerous form of breast cancer. That is, it grows slowly and is unlikely to spread so it is not necessary to treat it with chemotherapy. In fact, it wouldn’t even respond to chemotherapy if it was used. Instead, it can be treated with limited surgery, followed by radiation. Anti-hormone therapy, such as Tamoxifen, is usually prescribed for a 5 year period following surgery. Luminal A cancers are the ones that are usually detected by screening mammograms and the cure rate is greater than 90%. So you should never fear getting a mammogram because of the possibility of bad news. In fact, it is very important that you get regular mammograms and have cancer diagnosed early if it is there. Some researchers think that Luminal A cancers, which again are not very dangerous, can eventually mutate into Luminal B cancers, which are more serious. You want to get your cancer diagnosed before that happens.
Luminal B: The good news is that these cancers are less dangerous than Basal cell and Her2-positive cancers (see below), but unlike Luminal A cancers they are moderately aggressive in their drive to grow and spread. Some women with these cancers will benefit from chemotherapy. The MammaPrint and Blueprint tests help distinguish which patients should receive this treatment.
Basal cell: These tumors are considered very aggressive, fast-growing, and likely to spread – even more so than Luminal B cancers. Most (about 90%) do not have estrogen and progesterone receptors on their cell surfaces. In addition, these cancers don’t overproduce an oncogene (a gene that can cause cancer) called Her2. Because these tumors tend to be negative in these three areas, they are sometimes known as “triple negative.” Chemotherapy is effective with basal cell tumors. New treatment options are also emerging that could potentially improve outcomes. Pre-operative chemotherapy is sometimes prescribed to determine what drugs the tumor may respond to prior to surgery.
Her2-positive tumors are the most aggressive breast tumors. But we’re getting better at treating them, using an antibody to the Her2 receptor and certain chemicals called labatinib and neratinib, which target the cancer cells and kill them.
Speaking of genomic tests, they are not just applicable to breast cancer. They have the potential to change the way many different types of cancer are diagnosed and treated, for the better. For instance, a working group of the National Cancer Institute is now recommending that by expanding use of these tests, we can prevent a lot of the overdiagnosis and overtreatment of cancer currently taking place – not just with breast cancer but also prostate cancer, lung cancer, and thyroid cancer.
Again, for more information on the different types of breast cancer, there’s a free download available from my book, “The Breast Cancer Survival Manual.” Click here for that chapter.
Dr. John Link is the medical director of oncology for Breastlink, a network of comprehensive breast health centers in Southern California.
