Metastatic breast cancer (MBC) is breast cancer that has spread to other parts of the body. Treatment depends on a variety of factors.
A person’s tumor profile is important in determining the treatment options. The details of the tumor profile indicate which of three types of receptor are present in cancer cells:
- estrogen receptor
- progesterone receptor
- HER2/neu receptor
If the cancer is estrogen receptor- or progesterone receptor-positive, it means that hormones in the body influence the breast cancer. People with MBC may use medications that block hormones, known as hormonal therapy, in all stages.
In premenopausal females with MBC, first-line treatment involves tamoxifen or an aromatase inhibitor to suppress the ovaries and block hormones. In postmenopausal females, treatment does not involve ovarian suppression but does use hormonal therapy with an aromatase inhibitor.
As mentioned above, the initial combination of medications for people with estrogen receptor- or progesterone receptor-positive cancer depends on the occurrence of menopause. Chemotherapy may also be an option for first-line treatment.
The specific regimen depends on multiple factors, including the use of any previous regimens.
It is also important to consider the medical condition of the recipient. Medical teams should also consider the presence of any other medical concerns present, such as heart disease, before recommending treatment options.
Advances in treatment of MBC continue to evolve. It is important that people with MBC ask their medical team if there are any new strategies specific to their tumor type, taking their medical history into consideration.
The tumor profile determines the targeted therapies for which a person with MBC may be a suitable candidate. In those with HER2-positive breast cancer, doctors prescribe medication such as trastuzumab to counteract the HER2 receptor.
Pertuzumab (Perjeta) is another MBC agent focused on blocking the HER2 receptor. Doctors often prescribe it in combination with trastuzumab and chemotherapy.
T-DM1 (Kadcyla) is also an option when treatment has already involved trastuzumab and chemotherapy.
When multiple therapeutic options have not worked, oncologists can weigh up other targeted options specific to a person’s condition.
For people with HER2-negative, estrogen receptor- or progesterone receptor-positive cancer, additional options include palbociclib (Ibrance), which is a CDK4/6 inhibitor, and letrozole or fulvestrant, which are anti-hormone receptor therapies for postmenopausal hormone blockade.
Targeted treatments can result in known potential side effects. Medical teams will carefully monitor people for these side effects both during and after treatment.
Trastuzumab, for example, can impact heart function in a small percentage of people. A patient’s medical team will monitor their heart health starting before treatment and reconsider the therapy if concerns arise.
Many centers have a cardio-oncology program where oncologists and cardiologists can work together to optimize heart health during cancer treatment.
Other side effects associated with some targeted treatments include:
- low white blood cell count, or neutropenia
- irregularities in liver function
A patient’s medical team will discuss side effects specific to each treatment, and they can work together to manage them.
Sometimes, oncologists will recommend a change in therapy for side effects that are intolerable or too harmful to continue.
When MBC progresses during treatment, there may be other therapeutic options specific to the tumor profile.
Advances in treatment for MBC continue to evolve, and options often exist. Before implementing any of these, medical teams must consider treatments based on individual tumor factors and the patient’s overall condition.
Joint decision making is an important part of MBC management. It is important that oncologists explain the various considerations to their patient and ask for their thoughts before implementing a plan.
For anyone with a cancer diagnosis, including one of MBC, it is easy to feel a loss of control.
However, it is important for people to remember that their medical team has support networks in place, and that its members are partners in a person’s care.
In addition to providing tailored treatment options, there is also a focus on improving quality of life and reducing treatment side effects that may negatively impact this goal.
Stress reduction techniques, such as meditation and yoga, have a positive impact on quality of life. The effect of yoga in people with breast cancer requires more research, but evidence suggests that it is associated with decreased fatigue, improvements in sleep, and a better quality of life overall.
Studies have also shown exercise to decrease pain and fatigue in people with MBC, including for individuals with advanced cases.
Researchers do not yet fully understand the impact of obesity on breast cancer progression. However, studies do confirm a link between obesity and an overall increased risk of developing breast cancer.
Maintaining a moderate weight for overall health and well-being is important regardless of stage. In general, people with MBC should avoid alcohol and adopt a diet rich in fruits and vegetables.
Researchers are continuously engaging in and evaluating MBC studies. Clinical trials can help oncologists identify new treatment options — ideally those that offer improved outcomes with few side effects.
Medical teams will assess whether or not an individual is a suitable candidate for a clinical trial.
There is no one-size-fits-all outlook for people with MBC. In determining an outlook, doctors must consider the context of the individual and the tumor profile.
While MBC is not currently curable, it is treatable. Importantly, research efforts continue and contribute to impressive advances in treatment.
Dr. Michelle Azu is a breast surgical oncologist who completed her breast surgery fellowship training in 2009 at Memorial Sloan Kettering in New York City, NY. Currently, Dr. Azu is the director of breast surgery at a regional network hospital for a healthcare system in New York City. She is also an assistant professor of surgery for an academic institution in New York City.
Dr. Azu always looks forward to new opportunities to share advances in breast cancer research. She has received numerous honors throughout her career and makes every effort to provide outstanding, evidence-based, compassionate care tailored to her patients.