Localization of hematoporphyrin: derivative to human colorectal cancer

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.)

Measurement, Fluorescence, Endoscopy, Hematoporphyrin

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Postoperative active specific immunization in colorectal cancer patients with virus-modified autologous tumor-cell vaccine: first clinical results with tumor-cell vaccines modified with live but avirulent Newcastle disease virus

Article Abstract:

In general, the development of cancer seems to require the tumor's escape from surveillance by the immune system. Furthermore, experiments in laboratory mice have demonstrated that animals may be protectively immunized against their own tumors. However, little is known about how this information might be used in devising therapies for cancer patients. With the participation of patients with colorectal cancer, researchers are exploring the methods by which a satisfactory immune response against tumor cells may be achieved in humans. After surgical removal of the colon cancer, the cells may be prepared for immunization of the patient; the researchers prepare whole cancer cells for injection rather than merely a chemical extract of the cancer cells. But since human cells, by themselves, are generally poor antigens, the researchers added Newcastle disease virus to the tumor cell suspension. In contrast with some previous research, killed virus was not used, but rather an avirulent strain of Newcastle disease virus which cannot pass into uninfected cells was used. The progress of the immunization was monitored by observing the delayed type hypersensitivity (DTH) response in a skin test. The skin test revealed that a specific immune response against the individual patient's tumor cells could be observed in 12 of 16 patients. Curiously, a cellular immune response specific for the virus was not observed. Although the results indicate that a specific antitumor cellular immune response can be achieved against human tumor cells, there is not yet any evidence that this response can provide any clinical benefits for the patient. (Consumer Summary produced by Reliance Medical Information, Inc.)

Methods, Evaluation, Drug therapy, Immunization, Immunologic adjuvants, Immunological adjuvants, Newcastle disease

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The value of immunoscintigraphy for the operative retreatment of colorectal cancer; limitations of a new diagnostic method

Article Abstract:

A study of the effectiveness of immunoscintigraphy with labeled monoclonal antibodies for the detection of tumor-associated antigens (substances that induce antibody formation) in colon cancer was conducted in 42 patients. The goal of the study was to verify to what extent immunoscintigraphy is superior to conventional diagnostic methods in cases of suspected recurrent colon cancer. Nuclear cameras were used to record the X-ray emissions of radioactive monoclonal antibodies (genetically engineered antibodies that are labeled with a radioactive substances to mark the position of viruses in the body) when they became attached to cancer cells in the colon. It is important to detect recurrent colon cancer as soon as possible for effective surgical removal of the cancerous sections of the colon. Immunoscintigraphy using radiolabeled monoclonal antibodies was not as successful as the standard diagnostic methods (e.g., ultrasonography or computed tomography) in the detection of recurrent colon cancer. This research does not support the findings of other studies in which immunoscintigraphic techniques were successful in diagnosing recurrent colorectal carcinoma. The development of more specific monoclonal antibodies and the labeling of these substances with different radionuclides may improve the diagnostic accuracy of the technique.

Research, Cancer, Monoclonal antibodies, Cancer recurrence, Radionuclide imaging, Radioisotope scanning

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