Article Abstract:
As with many other cancers, the prospects for successful treatment of colorectal cancer improve greatly if the cancer is detected in its early stages. However, there are not yet any satisfactory screening tests which reliably detect colorectal cancer in its presymptomatic stages. The test for hidden blood in the feces is commonly used, but 80 to 90 percent of the positive results of this test will prove not to be cancer and 20 to 40 percent of the actual cancers will be missed by this test. One possible screening mechanism may be to simply wash out some cancer cells from the colon and look at them under the microscope. A preliminary trial of just such a test (oral lavage test) was carried out on nine patients with known colorectal cancer and 18 patients without signs of cancer after careful examination including colonoscopy (in which the colon is examined using a flexible instrument). The patients were asked to drink two liters (just over two quarts) of clear solution containing only the necessary salts for proper balance. After 12 hours, the patient drank four more liters of the same solution. The first two bowel movements after drinking this fluid contained particulate matter and were not used. The next three bowel movements were progressively clearer. The liquid was strained through gauze and then placed in a centrifuge so that any cells present could be spun to the bottom of a test tube and collected. The collected cells were then examined by a pathologist who had not been told the diagnosis of the individual patient. Of the nine patients with colorectal cancer, the recovered cells were deemed suspicious for cancer in three cases and positive for cancer in six. Of the 18 patients without colorectal cancer, 17 were deemed negative and only one was deemed suspicious. The results of this study indicate that a sufficiently large number of cells from the colon and rectum are shed and can be easily collected and analyzed by conventional techniques. Further research will be necessary to determine if this method can be used as an effective screening procedure for the early stages of colorectal cancer. (Consumer Summary produced by Reliance Medical Information, Inc.)
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Article Abstract:
Hematoporphyrin derivative (HpD) is selectively retained by a number of different tumors. Tissue that has retained HpD may be identified by fluorescence, and this property has been used to endoscopically detect tumors in the trachea, bronchi, and bladder. The technique might also be used to identify colorectal tumors, but little is known about the affinity of gastrointestinal cancers for this compound. Although the retention of HpD in colorectal tumors in experimental animals has been verified, it is important do determine that the same process occurs in human tissue. To answer this question, surgical specimens of colorectal cancers were examined with fluorescence videodensitometry. Ten patients were injected with between 2 and 5 milligrams per kilogram of body weight of hematoporphyrin derivative, 3 or 72 hours before surgery. After surgery, the specimens were photographed under ultraviolet light with a 35mm camera. The negatives were then analyzed with a video camera and computer that were capable of quantifying the density of various points on the photographic negative. In all ten specimens, the tumor had a stronger fluorescence than the surrounding tissues. Of the ten specimens, nine were adenocarcinomas, and one was a cloacogenic small cell cancer. This small cell cancer had the lowest level of fluorescence. The average fluorescence was about six times that of the surrounding tissues. In this study, the fluorescence of tumor tissue was greater for the injection 72 hours prior to surgery than for the injection three hours before. Although this study has not evaluated the numerous factors which might contribute to HpD affinity, such as tumor vascularity, histological type, pigmentation, and lipid content, the demonstration of selective retention by colorectal tumors is promising for the development of newer diagnostic methods. (Consumer Summary produced by Reliance Medical Information, Inc.)
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Article Abstract:
The death rate from stomach cancer in Western nations is declining. This is due to the incidence in the disease itself; there have been no significant improvements in the treatment of stomach cancer in the last 40 years. The majority of cases of stomach cancer are already advanced at the time they are diagnosed; in Europe and the United States only 5 to 15 percent of stomach cancers are diagnosed early stages. As a result, much of the surgical treatment for stomach cancer is designed with no hope for curing the patient, but only to ameliorate the symptoms and stretch the patient's survival a bit. When the goal of treatment is only palliative, it becomes more difficult to evaluate treatment methods. Patient survival, an easy-to-make objective measure, is no longer relevant; what is important is the quality of the patient's remaining time. Therefore, it has been controversial whether it may be appropriate to remove the entire cancerous stomach in some cases. In a review of 53 cases over a 10-year period, investigators found that, in many cases, total gastrectomy is, indeed, justified. Of the 53 patients who underwent total gastrectomy, four died of postoperative complications. Another six had complications which necessitated further surgical procedures. However, despite the advanced cancer among these patients, the median survival was fairly good at 19 months. Furthermore, 13 patients survived more than two years. These patients enjoyed a reasonable good quality of life during this time. Quality of life was rated good in 59 percent of the cases and satisfactory in another 28 percent. In only 13 percent was the quality of life rated poor. These observations indicate that for some patients with stomach cancer the total removal of the stomach is a palliative procedure with beneficial results. (Consumer Summary produced by Reliance Medical Information, Inc.)
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