At least in industrialized countries, the two major causes of death are heart disease and some form of cancer. I don’t know about you, but if I had to choose my poison, I’d prefer heart disease, because cancer is so slow, insidious, and creepy. Besides, my wife is a breast cancer survivor (http://breastcancer.about.com/) and both my parents died of cancer. So when I heard about a research team at Massachusetts General Hospital that has moved a blood-test machine for cancer cells closer to commercialization, I had mixed feelings.
So far, the device is apparently intended only to monitor the condition of patients who are already known to have cancer. It consists of a credit-card-size plate covered with thousands of tiny posts, each one of which has a different kind of molecule that binds to proteins on a specific type of cancer cell. When blood flows over the posts, very small concentrations of cancer cells leave traces on the posts, and you get a number saying how many of what kind of cell is present in the blood. The hope is that this kind of test can supplement or even replace the expensive MRI or CT scans usually employed to monitor progress of chemotherapy by observing the size of macroscopic tumors. Of course, there are many potholes in the road to commercial use, but the researchers have my best wishes for success. I think.
Let’s extrapolate this kind of technology to its ultimate limit. We are told that everybody has some cells that are, if not out-and-out malignant, then highly inclined to develop into cancer. But in healthy people, the immune system is on the lookout for such misbehaviors as a liver cell setting up shop in your biceps muscle, and takes care of misbehaving cells by attacking them as though they were foreign invaders like bacteria. Cancer is not so much the mere occurrence of malignant cells as it is their successful multiplication into a colony whose numbers and size overwhelm the body’s defenses.
So what if we had a blood test for any kind of cancer cell, down to the concentrations that exist in healthy people? Would that be a good thing?
On the face of it, yes. I suppose you could establish some kind of baseline limit as we have done for serum cholesterol. Below the limit you’d be told you were healthy and above the limit, well, you’d be worried, at least. We’d have to go through clinical trials to see what kind of numbers are associated with cancers that are worth fighting. We are already in this situation with regard to the protein-specific antigen (PSA) for prostate cancer. There is a simple blood test that tells you your PSA level, but it turns out that PSA is not an infallible signal that tells you either (a) you’ve got nothing to worry about or (b) make sure your will is in order and you’ve picked out the music you want for your funeral. And even people who have genuine prostate cancer, depending on their age, are sometimes told that not treating it is an option because treatment can sometimes be worse than the disease. But it’s hard to tell when that’s the case.
If we are so tangled in ambiguities about as simple a thing as the PSA test for prostate cancer, imagine what it would be like if we had a blood test, even a reliable one, for most of the common dangerous cancers such as those of the lung, breast, colon, skin (including melanoma), and so on. On the one hand, it’d be nice not to undergo chest X-rays, mammograms, and colonoscopies and instead just provide a blood sample. But on the other hand, I’m sure we would face a world of difficult decisions that would be highly biased by the economics of cancer treatment. When you add the current U. S. health-care law (and its future fate) to the mix, you get quite a brew that could raise as many problems and issues as it solves.
Does this mean we should stop such research? I don’t think so. Knowledge as such, including knowledge of one’s physical condition, is of value, but only if we also consider the context in which such knowledge will be used. It does no good to come up with a cheap test for cancer if we do not also use that new knowledge to work on better and less debilitating treatments that take advantage of the early notice that such a test would give. Otherwise you move toward the ultimate nightmare (which fortunately will never come to pass) of knowing at the outset that for example you, a 23-year-old man, will die at the age of 46 of thus-and-such disease, but there’s nothing anybody can do about it.
My metaphorical hat is off to the MGH researchers, and I hope they succeed in at least their immediate goals of developing better ways of monitoring the progress of cancer treatment. As to the ultimate cancer blood test, if it ever comes to pass, let’s just hope that by then we have come up with a wise way to use it for the benefit of patients as well as the medical industry.
Sources: MIT’s online version of Technology Review carried an article about the MGH research on Jan. 3, 2011 at http://www.technologyreview.com/blog/editors/26218/.