Jewish World Review Feb. 8, 2002 / 26 Shevat, 5762




Possible breakthrough in early cancer diagnosis

By Robert A. Wascher, M.D., F.A.C.S.

http://www.NewsAndOpinion.com -- THE journal Lancet has just rushed to publication a study that employs an innovative new approach to diagnosing cancer. The authors initially studied patients with known ovarian cancer, using a highly sophisticated test called mass spectroscopy. A computer was then used to analyze thousands of proteins in the blood of 50 patients with known ovarian cancer and 50 patients without cancer.

The computer program was subsequently able to identify patterns of specific proteins in the blood that appeared unique to the patients with ovarian cancer. After these cancer-specific patterns were deciphered by the computer, the authors then applied the test to another 116 women.

Unknown to the investigators, 50 of these 116 women had ovarian cancer and the other 66 were healthy women without cancer. Using mass spectroscopy and the pattern analysis data from their initial study, the new test correctly identified all 50 women with ovarian cancer, including 18 cases of very early stage (stage I) cancer. Among the 66 "negative control" women, 63 were correctly identified by the test as being free of ovarian cancer, while 3 women had a false-positive test.

This is a dramatic breakthrough in the field of cancer diagnosis in general, and especially so with respect to ovarian cancer. Ovarian cancer typically produces minimal-or no-symptoms until the disease reaches a very advanced stage.

At the present time, more than 80% of ovarian cancer patients are initially diagnosed when their disease has already spread throughout the abdomen, accounting for the poor survival rate of 30-40% at 5 years following diagnosis. On the other hand, when ovarian cancer is still confined to the ovary, the 5-year survival rate is better than 90%. Ovarian cancer can affect women of any age, although it is more common in patients 60 years or older. Because the ovaries are protected deep within the pelvic cavity, early stages of ovarian cancer are rarely diagnosed, although the diagnosis may be made incidentally during evaluations for other conditions.

A family history of ovarian cancer, as well as certain breast cancer-specific gene mutations (e.g., BRCA-1 and BRCA-2), significantly increases the risk of ovarian cancer. At the present time, the only blood test approved as a screening test for ovarian cancer (or for following ovarian cancer patients for evidence of recurrence) is the CA-125 blood test.

Unfortunately, this test is not very sensitive during the early stages of the disease and, hence, is not useful as a screening test. The new protein-based mass spectroscopy test used in this study is in the vanguard of a new field that has many potential applications to Oncology. Proteomics, or the study of proteins to diagnose and analyze various disease states, including cancer, is one of the next great frontiers in Medicine. While study of the genes can tell us much about a patient's predisposition to develop a disease, only the end product of any gene, the protein that it codes for, is the final and specific evidence of the actual presence of a particular disease in a particular individual.

MAMMOGRAPHY: THE CONTROVERSY CONTINUES

I have previously reported on the growing controversy about the value of routine screening mammography. A recent retrospective analysis of previous studies of mammography's usefulness concluded that there is no compelling evidence that mammography saves lives. This, of course, is completely contradictory to the beliefs of both the medical profession at large and the general public. The previous review paper, published in the journal Lancet, set off a firestorm of debate around the world, although the authors did not perform any new research of their own (they simply critically reviewed existing studies).

A new report in the Lancet, however, questions the analysis of the previous review paper, as well as its conclusions. Essentially, the new report criticizes the previous review for comparing the results and conclusions of two different studies that had very different designs, and for failing to consider early-versus-late outcomes in the patients who participated in the two screening mammography clinical trials that were previously analyzed.

Upon reanalysis of the previously analyzed mammography study with the longest patient follow-up, the conclusion of the new report's authors is that screening mammography does, in fact, save lives. The new review's authors looked specifically at older women in the previous mammography study (the group at greatest risk of developing breast cancer), and concluded that there was a 55% reduction in death due to breast cancer among the group that received regular screening mammograms as compared to women not receiving mammograms.

There are certain to be additional studies and critiques forthcoming, but the results of this analysis are more in line with the observations of clinicians who treat large numbers of women with breast cancer. As I have indicated before, none of the major cancer organizations in the United States are recommending that women deviate from the current recommendations regarding screening mammography at this time.

CPR TECHNIQUES REVISITED

Currently, if you happen across a person who is unconscious and who appears to have suffered a heart attack, the Red Cross recommends that you and any other CPR-trained "rescue person" initiate CPR (cardiopulmonary resuscitation). Although the sequence of one-rescuer and two-rescuer CPR has been subtly modified over the years, the routine has pretty much remained the same over the past decade.

If two rescuers are available, then one rescuer blows air into the patient's lungs while the other performs chest compressions in a synchronized fashion. If you are alone, then you are expected to alternate chest compressions with rescue breaths. Obviously, during the time when you are blowing into the patient's mouth (for adults patients), the heart is not being compressed and, assuming the patient's heart has stopped functioning, no blood is flowing through those lungs that you are trying to fill with life-giving oxygen.

A new study, as reported in the journal Circulation, challenges the effectiveness of the current one-rescuer CPR method. Using pigs as a model, the researchers artificially induced an abnormal heart rhythm that often occurs following a heart attack (ventricular fibrillation, which is essentially a useless quivering of the heart muscle).

The animals were then randomized to receive either standard one-rescuer CPR (cycles of 15 chest compressions followed by 2 breaths) or continuous chest compressions alone. Fifteen minutes after the heart was put into ventricular fibrillation, and CPR started, the animals' hearts were restarted with an electrical shock, and they were then observed in an intensive care unit for 24 hours.

The findings were rather dramatic. Twenty-four hours after having their hearts restarted, 12 out of 15 of the animals receiving continuous chest compression CPR were free of any evidence of brain damage due to lack of oxygen. The animals that received standard one-rescuer CPR fared much worse, with only 2 of 15 animals appearing neurologically intact 24 hours after their hearts were restarted.

This study will almost certainly lead to additional research to see if continuous chest compression CPR has the same benefit over the present standard one-rescuer CPR method in humans.

JWR contributor Dr. Robert A. Wascher is a senior research fellow in molecular & surgical oncology at the John Wayne Cancer Institute in Santa Monica, CA. Comment by clicking here.

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© 2002, Dr. Robert A. Wascher