A meaningless boost
Repeatedly, we are reminded that early diagnosis and early treatment are major reasons for the improvement. We have better diagnostic tools and screening methods than ever before; more mass screenings for the public are scheduled, often by charities serving populations with poor health services; family practitioners are more aware of the disease and its early symptoms; and more patients are now aware of the symptoms that might warrant a trip to the quack. Of course, the treatments themselves have improved as well, and this certainly is having some effect.
However, the item that we need to question most carefully is the effect of early diagnosis and early treatment. Treatments are starting earlier these days, and we are all "surviving" longer with cancer. But just how fabulous is that news, really?
The cancer treatment industry desperately wants us to think it's beyond fabulous: cancer drugs, and related diagnostic and treatment devices, are among the most expensive, and most profitable, known to medicine. There are those who profit from our assumption that early diagnosis and treatment extend patients' lives. And profit they do: think of the hospitals, drug makers, device makers, diagnostic technicians, radiotherapists, surgeons, and oncologists. Cancer treatment is a vast, complex industry, and like any industry it flourishes best in a field of semi-educated consumers.
And so we are subtly shepherded toward the belief that our deaths from cancer will be postponed significantly because of early, and very costly, medical intervention.
Unfortunately, this is not always easy to prove. And the word "survival" itself is tricky, and normally used in a relative context, as mentioned previously. Indeed, you can "survive" longer than another patient with the same cancer, but not actually live any longer, because the survival clock starts running on the day of diagnosis. Thus, everyone who is diagnosed early automatically survives longer, independent of any other variable. Conversely, if you are diagnosed late, you are not going to "survive" for long, although you might already have lived for quite a long time with your cancer.
So it is hardly time to break out the noise makers and Champagne merely because the survival numbers have doubled. Let's go to an illustration: imagine a doctor with a patient who has got Stage IV (metastatic) cancer at the time of diagnosis. Now, one might ask the doctor a few questions, such as, how long did the patient take to progress from Stage I to Stage IV? Or, just when did carcinogenesis actually occur - six months ago? Six years ago?
Of course, no one can say with certainty; patients are individuals, and diseases work differently in different people (as do drugs and other treatments, by the way). But because our example patient is diagnosed at Stage IV, we'll learn only how long the disease needs to kill them when treatment starts at that point.
Now, compare this to a patient with the same disease, only Stage II at the time of diagnosis. If there is good treatment and follow-up, we'll get a detailed picture of how long the disease needs to kill this early-treatment patient. But because we don't know the late-treatment patient's disease history, we can't say much about how long that patient has lived with their cancer, and thus it is difficult to compare the progress of these two hypothetical patients.
Did the Stage IV patient progress faster from Stage I than the early-treatment patient did? We might assume that they did, but we don't really know. Indeed, their own body might have fought the disease well, and they might possibly have lived longer with untreated cancer than the early-treatment patient lived with treated cancer. This might be unlikely, but the uncertainty here is nonetheless real.
Oncologists who see hundreds of patients over the years will get a sense of the disease's natural progress, and should be able to say with some confidence that when this or that type of cancer is left untreated, it usually progresses a lot faster than it does when it's treated. And that instinctive sense, learned from experience and observation, is probably reliable, although it should be noted that it isn't proof.