What does cure mean to a cancer patient?
That the cancer has totally disappeared? To your doctor cure actually means something much simpler: your cancer is no longer a threat to your life. Everyone dies, and eventually--hopefully many years later--when you do die it will not be from the cancer.
Many oncologists find the term cure irrelevant. Why? Even if your treatment program is so successful that it eliminates any cancer visible through traditional imaging techniques, we can’t discount the idea that you might have small cancer deposits, or micrometases, somewhere in your body that will at some point grow big enough to cause problems for you. Scientists call this tumor dormancy. The mechanism is immunological. It involves both specific (adaptive) and non-specific (innate) immunity.
When these micrometastases do grow large enough to show up on imaging, there are oftentimes only a few of them. This is called oligometastatic disease. Oligometastatic disease is defined as 5 or fewer metastases that appear outside of the original organ where the cancer started--i.e. lymph node and, for example, not prostate if you have prostate cancer, or bone and not breast if you have breast cancer.
But now that our imaging techniques have become ever more precise, we can not only detect these smaller metastases sooner, we can also more accurately target them with radiation and with robotic surgery techniques. With the development of PET scans, we can even determine whether these metastases are alive.
Often, we use a multi-pronged approach: we’ll remove the mets with radiation or surgery then use what’s called a systemic treatment. A systemic treatment is essentially a drug that circulates throughout the body rather than being directed at a single site.
This approach can be more or less effective, depending of course on your cancer type and on your own individual cancer.
But what if your doctors can’t detect any of these micrometastases after treatment. You are what seems to be cancer free for decades. You think you’re cured.
Your doctors are careful not to tell you that you’re cured, but rather that your cancer is dormant. What does that even mean, you might think.
Before your primary tumor was eliminated, that tumor could have released what are called disseminated tumor cells. These disseminated tumor cells, also called DTCs, can become lodged in distant organs like bone, lung, and other tissues where they can live for many years before reawakening.
Is your cancer asleep? Essentially. We just don’t completely understand yet why some cancers go dormant and others to stay awake. Nor do we understand what triggers some of those dormant cancers to reawaken.
But we do know quite a bit more about what we can do to keep these cells dormant. Examples are keeping the androgen level low in prostate cancer or keeping the estrogen level low in hormone receptor positive breast cancer.
When there are a few targetable lesions, we can radiate or use hyperthermia to both kill that one metastasis and simultaneously vaccinate the body to encourage the immune system to eliminate a distant metastasis that was not treated. Radiation therapists have observed this phenomenon for years. They called it the abscopal effect. It is now proven that this happens via the immune system.