Our Knowledge of Cancer Remains Incomplete
by Richard Daverman, PhD
Centient Biotech Investor
Earlier, we reported on the confusion about terminology in cancer results, a confusion that makes the results of some trials seem better than they really are. A recent essay in the New York Times (free registration required) underscores that point. In fact, the authors argue that even an increase in survival, often considered the Holy Grail in cancer studies, may be considerably less than it seems.
Here’s the problem: the two most prestigious medical journals in the country, the New England Journal of Medicine and the Journal of the American Medical Association, presented reputable scientific work on lung cancer that came to opposite conclusions. The NEJM found that spiral CTs, a 3-D chest x-ray, could render most lung cancer curable. On the other hand, the JAMA concluded that spiral CTs were, at best, of inconclusive value and could actually prove harmful.
How could this happen? How could large tests come up with such different calls for action? The answer, according to the authors, is two-fold: survival - the length of time between diagnosis and death - is not the same as mortality, which is the age at death. And really, most people want to live to a greater age, not just live longer after they have received a cancer diagnosis. That is, if a patient is diagnosed at an earlier stage in the progress of cancer, the patient’s survival is usually increased. So, if the patient is diagnosed at age 52 instead of age 62, the survival time is greatly increased, even if the treatment does nothing to prolong life and the patient lives to age 67 in any event.
The second implication is perhaps more revolutionary: not all cancers inevitably progress in severity. Some stay the same and some disappear.
The authors look at a long-term, double-blind study done at the Mayo Clinic. After the link was made between smoking and lung cancer, patients were screened for lung cancer using spiral CTs. As expected, survival doubled. This bolstered the usual “See-your-doctor; get-regular-checkups; treat-it-early-before-it-gets-out-of-hand” philosophy that has been beneficial with other forms of cancer.
But there were some anomalies in the study. Ten years after the test, the researchers did a follow-up. The screened group still had more cancer than the placebo, which was not supposed to happen because cancer should have been distributed evenly in a large test. In Japan, spiral CTs were administered to smokers and non-smokers, and it was discovered that non-smokers had just as high an incidence of lung cancer as the smokers. But a smoker is 10 to 20 times as likely to develop lung cancer. The only logical conclusion is that many cases of lung cancer do not progress into full-blown deadly disease.
Here is where the problem starts. Any case of lung cancer gets treated, because of the “get-it-early-while-you-still-have-a-chance” theory. However, about 5% of all people who undergo surgery for lung cancer will die within 30 days. And the presumption is that not all of them die because their disease is so advanced.
Thus, a spiral CT has the possibility of diagnosing a cancer that may not cause the patient harm - not all cancers progress - but because the inevitable treatment might be deadly, the diagnostic event sets in motion a plan of action. And the resulting surgery could be more harmful than having avoided the doctor’s office in the first place.
The authors of the essay say that we don’t know that this is correct. We know only that we don’t know. Until a placebo-controlled trial is conducted, we are guessing. Such tests are underway.
Nevertheless, the surprising results point out, once again, a no-longer-so-surprising conclusion: our understanding of cancer remains incomplete (we are in need of a better paradigm for how cancer works), and our means of measuring progress, using metrics like “survival,” may not be as clear as we thought.
Source: CentientInvestor.com
RELATED READING:
- Inovio Biomedical: Tumor Ablation Technology Tempting to Big Pharmas
- Geron's Research Arsenal: Stem Cells, Cloning, Cancer
____________________
Centient Biotech Investor
Earlier, we reported on the confusion about terminology in cancer results, a confusion that makes the results of some trials seem better than they really are. A recent essay in the New York Times (free registration required) underscores that point. In fact, the authors argue that even an increase in survival, often considered the Holy Grail in cancer studies, may be considerably less than it seems.
Here’s the problem: the two most prestigious medical journals in the country, the New England Journal of Medicine and the Journal of the American Medical Association, presented reputable scientific work on lung cancer that came to opposite conclusions. The NEJM found that spiral CTs, a 3-D chest x-ray, could render most lung cancer curable. On the other hand, the JAMA concluded that spiral CTs were, at best, of inconclusive value and could actually prove harmful.
How could this happen? How could large tests come up with such different calls for action? The answer, according to the authors, is two-fold: survival - the length of time between diagnosis and death - is not the same as mortality, which is the age at death. And really, most people want to live to a greater age, not just live longer after they have received a cancer diagnosis. That is, if a patient is diagnosed at an earlier stage in the progress of cancer, the patient’s survival is usually increased. So, if the patient is diagnosed at age 52 instead of age 62, the survival time is greatly increased, even if the treatment does nothing to prolong life and the patient lives to age 67 in any event.
The second implication is perhaps more revolutionary: not all cancers inevitably progress in severity. Some stay the same and some disappear.
The authors look at a long-term, double-blind study done at the Mayo Clinic. After the link was made between smoking and lung cancer, patients were screened for lung cancer using spiral CTs. As expected, survival doubled. This bolstered the usual “See-your-doctor; get-regular-checkups; treat-it-early-before-it-gets-out-of-hand” philosophy that has been beneficial with other forms of cancer.
But there were some anomalies in the study. Ten years after the test, the researchers did a follow-up. The screened group still had more cancer than the placebo, which was not supposed to happen because cancer should have been distributed evenly in a large test. In Japan, spiral CTs were administered to smokers and non-smokers, and it was discovered that non-smokers had just as high an incidence of lung cancer as the smokers. But a smoker is 10 to 20 times as likely to develop lung cancer. The only logical conclusion is that many cases of lung cancer do not progress into full-blown deadly disease.
Here is where the problem starts. Any case of lung cancer gets treated, because of the “get-it-early-while-you-still-have-a-chance” theory. However, about 5% of all people who undergo surgery for lung cancer will die within 30 days. And the presumption is that not all of them die because their disease is so advanced.
Thus, a spiral CT has the possibility of diagnosing a cancer that may not cause the patient harm - not all cancers progress - but because the inevitable treatment might be deadly, the diagnostic event sets in motion a plan of action. And the resulting surgery could be more harmful than having avoided the doctor’s office in the first place.
The authors of the essay say that we don’t know that this is correct. We know only that we don’t know. Until a placebo-controlled trial is conducted, we are guessing. Such tests are underway.
Nevertheless, the surprising results point out, once again, a no-longer-so-surprising conclusion: our understanding of cancer remains incomplete (we are in need of a better paradigm for how cancer works), and our means of measuring progress, using metrics like “survival,” may not be as clear as we thought.
Source: CentientInvestor.com
RELATED READING:
- Inovio Biomedical: Tumor Ablation Technology Tempting to Big Pharmas
- Geron's Research Arsenal: Stem Cells, Cloning, Cancer
____________________
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