By Heather Millar
One of the first things that freaked me out about cancer was the notion that it can move around the body, MY body. I spent the first few days after diagnosis obsessing over the idea that tiny cancer cells were careening around my bloodstream, trying to set up beachheads in various foreign countries, i.e. my other organs. Well, as an excellent overview, “Metastasis: The Rude Awakening,” in the current issue of the British journal Nature suggests, I wasn’t exactly wrong. Nor was I exactly right.
Here’s the problem, as the Nature story outlines it: While survival rates for breast cancer have improved; survival rates tend to steadily worsen decade by decade. Translation: Some cancers can reappear a decade after the oncologist says you have “No Evidence of Disease” (NED). Some come back two decades after you are pronounced NED. While not common, a few may take even longer to reawaken, 25 years or more. Apparently, some studies show that metastatic cells make tracks early: Escaped tumor cells have been detected in patients diagnosed with Ductal Carcinoma in Situ (DCIS), a form of breast cancer so early that it is often called “Stage 0.”
Scientists are trying to figure out exactly why this is so, the Nature piece explains. Do “circulating tumor cells” (CTCs) go dormant for a while, until they’re awakened by some environmental change, or some physical or chemical change in the body? Or do CTCs maintain the ability to spread, but just hang out in the bone marrow or the liver for a few years until conditions seem right? Why do some CTCs develop into full-blown metastases while others don’t? Is there a chemical barrier that prevents CTCs from dividing? Is it a lack of blood supply? Does a certain genetic switch need to be thrown?
Could a test for CTCs help to identify patients most at risk for metastasis? One CTC detector has been approved by the FDA, but apparently researchers say it still misses CTCs in about one-third of patients.
The main take-away, for me, is this: Cancer cells apparently ARE moving and changing around the body beginning very early in the disease process. But this doesn’t mean we’re all going to develop metastatic cancer. Our fate depends on a whole complex array of chemical, genetic, and environmental processes that scientists are only just beginning to explore.
As one scientist tells Nature, we need to redefine how we think about breast cancer. Maybe it makes more sense to think of it like a chronic disease, like diabetes. Maybe we need to think of it, not just as a single thing that can be cut out, or irradiated, but as a disorder that attacks our bodies as a system, a disorder that constantly moves, changes, and evolves.
I suspect that this may be true not only of breast cancer, but of many, maybe even most, cancers. That’s probably a big part of why, as Dr. Frank’s post this week points out, it’s so difficult to pronounce cancer “cured.”