Metastatic breast cancer, also known as advanced or secondary cancer, is where breast cancer has spread from the breast to other parts of the body, such as the bones, liver, brain or lungs. While no reliable data is collected on the number of people living with metastatic breast cancer, it is estimated that 5-10 per cent of people diagnosed with breast cancer each year will have metastatic breast cancer. In addition, 20-30% of people diagnosed with early breast cancer will go on to develop metastatic disease.
Dr Shom Goel, a clinician-scientist at the University of Melbourne and Peter MacCallum Cancer Centre, answers some key questions.
In addition to maintaining a clinical practice as an oncologist, Dr Goel also leads a research group, which positions itself at the intersection of cell cycle biology, epigenetics, and tumour immunology in breast cancer. They have developed several new transgenic mouse models of breast cancer, which have proven valuable for uncovering new mechanisms of drug activity and resistance, and their work has been published in high-impact journals including Nature, Cancer Cell and Nature Cancer.
He serves as either Global PI or Translational PI for four randomised clinical trials in breast cancer and was recently appointed Chair-Elect of the American Society of Clinical Oncology Education Committee. Dr Goel is also a recent awardee of a prestigious Snow Fellowship which will accelerate his laboratory’s work from 2022-2030. In conversation with Dr Goel.
✤ Can you explain what metastatic breast cancer is?
Metastatic breast cancer (also called stage 4 breast cancer) is breast cancer that has spread away from where it started to another part of the body. Common places for metastatic breast cancer to appear include the bones, lungs, liver, and brain, but a number of other organs can also (less commonly) be affected.
✤ Why does cancer metastasize?
Breast cancer begins when cells in the breast begin to divide uncontrollably. These cells can also migrate and invade the surrounding breast tissue. Sometimes, breast cancer cells will find their way into a blood vessel in the breast, which allows them to enter the circulation and travel to other organs. Once they reach these organs, the cells must then find ways to “stick” there, setting up camp and dividing repeatedly to form a new area of cancer.
✤ For what percentage of breast cancer patients does their cancer metastasize?
There are two ways metastatic breast cancer presents to doctors in oncology clinics. Less commonly, a patient will have metastatic breast cancer at the time their breast cancer is first diagnosed—this means it has already spread to other organs when we first meet the patient. We see that situation for about 5-10% of all breast cancer diagnoses. For the remaining 90-95% of patients who are initially diagnosed with non-metastatic breast cancer (meaning the cancer is only in the breast and nearby lymph nodes), just under a third will develop metastatic disease later on, months or years after their first breast cancer was treated.
It’s important for people to understand that there are many different types of breast cancer, and each person’s risk of developing metastatic breast cancer is different. So although these numbers tell us about the whole population, they don’t apply to any particular individual.
✤ Are there any contributing factors as to why people would be more susceptible to their breast cancer metastasising?
There are a number of factors which can influence the risk of breast cancer metastasising:
- Anatomical factors: primary breast cancers that are bigger, or have spread to the nearby lymph nodes, have a higher risk of coming back as metastatic breast cancer in the future
- Faster growing cancers have a higher risk of metastasising
- Certain subtypes of breast cancer have a higher risk of metastasising
Scientists are still trying to understand what it is that makes individual breast cancer cells more or less likely to invade into blood vessels, survive in the bloodstream, and successfully stick to and grow in other organs. This is a major topic in research labs but as of today, we don’t have treatments that specifically target those processes.
✤ Is the number of breast cancer patients with metastatic breast cancer increasing? If yes, why is that so?
Yes it is, but the reasons underlying this are complicated. One factor is that patients with metastatic breast cancer are surviving longer than before, meaning that there are more people alive with the disease at any one time—which is a good thing. In addition, the overall incidence of breast cancer is slowly increasing which has probably resulted in an increase in the overall number of people with metastatic disease.
✤ What is the life expectancy for metastatic breast cancer patients at the moment?
This is a tricky question for two reasons. First, the life expectancy for a person with metastatic breast cancer varies so much depending on the type of breast cancer they have and where it has spread to. Second, even when we know this information for an individual patient, doctors are not very good at predicting outcomes for any one individual.
A general answer is that life expectancy can range anywhere from a short number of months through to many years, or even decades. It’s important to note that overall, the life expectancy for patients with metastatic breast cancer is getting longer and longer, thanks to new therapies that have been developed.
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✤ What treatments can metastatic breast cancer patients take at the moment?
Most of the treatments for metastatic breast cancer are medicines. These could be chemotherapies, hormonal therapies, newer “targeted” therapies, and immunotherapies. We rely on medicine because they travel throughout the body and can thus treat breast cancer cells in many organs at the same time. Sometimes, we use radiation therapy—particularly if there are specific parts of the cancer that are causing issues such as pain. It’s rare to use surgery for metastatic breast cancer treatment but it is sometimes done—brain metastases are an example of tumours that are often removed surgically.
Importantly, the range and complexity of medicines available is rapidly evolving and we are seeing new therapies being approved for use in Australia every year.
✤ What medical trials are available at present for these patients?
There are many clinical trials available to patients with metastatic breast cancer in Australia and around the world. Many of these trials are testing new drugs—for example drugs that are targeting specific aspects of an individual’s cancer, immunotherapy drugs, or better versions of current drugs. In other cases, trials are asking how we can better use the drugs we already have. There are also trials testing new radiation therapy approaches and trials looking at ways to improve people’s quality of life (e.g. pain control, symptom management, psychological interventions, etc).
It’s important to ask your doctor about clinical trial options at every step in your treatment, and also to realise that different trials are available at different centres. These days there are large databases online which, with some help, one can navigate to explore options that might be suitable for them.
✤ Can patients expect longer life expectancy if they part in a medical trial?
It’s an interesting question. We have some data to suggest that overall, patients participating in trials do better than those who don’t. The reasons for this are complex—it might in part be due to the benefits of new therapies. But a large part of this is also because patients on trials typically have their care very carefully monitored, with an entire team of doctors, nurses, and research staff watching closely and adjusting treatments as needed.
✤ There is a lot of talk about improved quality of life -can you tell me what these improvements are?
Quality of life is a very broad term that basically describes one’s overall enjoyment of life. Thus, improvements in quality of life can be any that make life more enjoyable. These could be due to reductions in symptoms of a disease, fewer side-effects from treatment, or an improved state of psychological well-being—to name a few.
✤ What is the focus of metastatic breast cancer research at the moment?
It’s difficult to pinpoint one or two areas of focus. Metastatic breast cancer is a huge research topic and scientists and doctors approach it from many angles. These range from lab studies focused on understanding the behaviour of metastatic breast cancer cells, research to identify new drugs, clinical trials of new therapies, and measures to improve symptom management.
One area that many of us are focused on right now is drug resistance—we really need to understand why it is that medicines often control the growth of metastatic breast cancers for a time, only to eventually stop working. Given that we mainly treat metastatic breast cancer with drugs, resistance is ultimately a leading cause of metastatic breast cancer death.
✤ What would you like to see happen in the metastatic breast cancer research space moving forward?
I would like to see more resources put behind the research. Scientists and doctors around the world have no shortage of ideas, and their research has incontrovertibly improved the survival of patients with breast cancer. Unfortunately, however, we often see our research hindered by a lack of funding. People might be surprised to learn how much of a researcher’s time is spent writing grants and reports, rather than doing research. People have been talking about this issue for a long time, but if anything it’s becoming more dire (especially in Australia) these days.
(To learn more about metastatic breast cancer, available treatments and medical trials, Breast Cancer Trials is holding a free virtual Q&A on Monday 7th February 2022 from 5-6.30pm featuring Professor Sarah-Jane Dawson from the CAPTURE trial, other experts and metastatic breast cancer patients. You can register for this free event and submit a question for the expert panel)
Dr Shom Goel, a clinician-scientist at the University of Melbourne and Peter MacCallum Cancer Centre, answers some key questions about metastatic breast cancer. #TheIndianSun #breastcancerhttps://t.co/7s1vNjzLR4
— The Indian Sun (@The_Indian_Sun) January 19, 2022