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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

With the recent advances in the immunological surveillance system, an understanding of the role of host immunity has become essential to the management of carcinogenesis, tumor proliferation, recurrence and metastasis. Although it is important to continue chemical and surgical treatment of cancer, support of the anti-tumor immune system of the host should also be considered. Long term remission has been reported in leukemia by treating with BCG after chemotherapy whereas surgical treatment is usually more effective in preventing cancer recurrence in digestive organ cancer. The first step is extirpating the tumor as thoroughly as possible and the second step is chemo-immunotherapy. Cancer immunity, however weak, constitutes the basis for other treatments in selectively attacking cancer cells remaining after surgery, chemotherapy or irradiation. Immunotherapy should thus not replace chemotherapy or radiotherapy, but these methods should be employed in combination to attain more favorable results.
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PMID:Cancer immunotherapy with surgery. 14 59

Histochemical activity of acid DNAse, intensity of nucleic acid staining and histological alterations in mouse interfollicular epidermis (I.F.E.) were investigated after a single dose or after chronic topical administration of two hyperplastic agents, of which one (croton oil) was a potent tumor promotor, and the other one (podophyllin) did not promote skin carcinogenesis. Podophyllin induced intense uniform I.F.E. hyperplasia without any proliferation of poorly differentiated basal cells, without increased nucleic acid staining and without any appreciably decreased acid DNAse activity. On the other hand, croton oil (as well as TPA) produced almost immediate, distinct hyperplasia of poorly differentiated basal cells with increased intensity in the staining of both nucleic acids and nearly complete deficiency in acid DNAse activity. Similar histochemical and histological patterns were observed at the sites of wounding hyperplasia in untreated control mice. Such wounding hyperplasia was thought also to be a tumor promoting factor. It was suggested that the decrease in acid DNAse activity which occurred almost immediately after administration of potent tumor promoters and which could not be induced by a hyperplastic agent without tumor promoting action may have a particular importance in the mechanisms of tumor promotion.
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PMID:Induction of the deficient acid DNAse activity in mouse interfollicular epidermis by croton oil as a possible tumor promoting mechanism. 14 59

To better assess the significance of enzyme-deficient foci as putative premalignant lesions, parallel histochemical analyses of RNase and ATPase activities were carried out in serial sections of livers from rats fed 4-dimethylaminoazobenzene. The results showed that focal losses of RNase and canalicular ATPase activities occur simultaneously in congruent areas of liver parenchyma at early stages of carcinogenesis. Such foci presumably represent altered cells capable of progressing to neoplasia since the changes observed in this new cell population persist in developing tumors.
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PMID:Histochemical comparison of focal losses of RNase and ATPase activities in preneoplastic rat livers. 15 7

The results of experiments carried out to test some of the consequences of the earlier general theory of oncogenesis, according to which the malignant tumor cell can arise as a result of somatic hybridization of cells of different organ- and tissue-specificity, are described. In the first series a tumor induced by cellophane film, was grafted into syngeneic and allogeneic mice, and antilymphocytic serum (ALS) was then injected. Metastases occurred only in allogeneic recipients receiving ALS. It was thus shown that the ability of cells of this particular tumor to metastasize is not a property inherent in its cells but is acquired by them as a result of interaction with the recipient organism. In the second series it was shown by two immunological methods that the cells of metastases arising under these conditions contain tissue compatibility antigens of donor and recipient origin, i. e., that they are somatic hybridsmin the third series skin from individuals of another strain was grafted on to mice and ALS was injected; hepatomas developed in 74% of these mice. The theory is used to explain several phenomena of carcinogenesis not explicable by other theories: the phenotypic nature of cell transformation, the causes and nature of the duration of the latent period of tumor development, the mechanism responsible for the ability of tumors to overcome the system of immunological defense, the mechanism of activation of endogeneous oncogenic viruses, etc. Finally an answer is given to the question: what is a tumor?
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PMID:Somatic hybridization and oncogenesis; (Mechanism of formation of malignant tumors and metastases by the action of antilymphocytic serum). 16 99

The immune reactivity of patients with squamous carcinoma of the head and neck region was compared with that of patients with squamous carcinoma of the female pelvic organs and patients with adenocarcinomas, melanomas, and sarcomas. The reactivity of patients with clinically localized tumors was compared with that of cured patients and a large normal population. Patients with squamous carcinomas of the head and neck region and female pelvic organs displayed higher incidences of impaired cellular immune competence than patients with malignancies of other histologic types. Among cured patients, those previously treated for squamous carcinoma were unique in that they displayed cellular immune defects and serum suppressants of in vitro immune reactivity similar to tumor-bearing patients. Antibodies to herpes simplex virus nonvirion antigen was found in high incidence only among patients with squamous carcinomas, and the incidences in tumor-bearing and cured patients were similar. The persisting immune defects in cured squamous carcinoma patients give importance to the determination of the role of genetic and environmental factors in the induction of these tumors. The associations made between herpes virus and squamous carcinoma offer an explanation for the defects and also an approach for the definition of the factors involved in squamous carcinogenesis. The findings are clinically relevant to the isolation of population groups at high risk for the development of squamous carcinoma, as a rational basis for the development of prophylactic measures, and as a basis for more effective therapeutic regimens.
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PMID:Unique immunobiological aspects of head and neck squamous carcinoma. 16 42

In the course of methylcholanthrene induced carcinogenesis in rats, CIA50, C4 and C3 increased as compared with control and correlation of tumor size with increase in CIA50, C4 and C3 was observed. In the course of dimethylaminoazobenzen carcinogenesis of rats, complement level and C3 level decreased but in splenectomized rats fed by dimethylaminoazobenzen showed elevated level of complement system. After Corynebacterium infection, CIA50 and C3 of rats increased. This phenomenon is considered to be one of the essential factors to induce high resistance against tumor inoculation.
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PMID:Studies on rat complement. II. Complement level in experimental tumor in rats. 17 Apr 42

In vivo and in vitro studies bearing on tumor-specific and viral-associated antigenicity of human breast carcinomas were reviewed with particular attention to the following clinical considerations: (a) breast carcinomas arise in a nonrandom fashion; (b) in situ carcinomas precede invasive breast carcinomas; (c) invasive breast carcinomas behave in a heterogeneous fashion. Microscopically demonstrable lymphoreticuloendothelial responses, skin window tests, and leukocyte migration tests all indicate that tumor-specific antigenicity develops in assoication with the early phases of mammary carcinogenesis. Such antigenicity is maximally expressed in in situ carcinomas without associated invasive breast cancer and minimally in invasive breast cancers with metastases. Immunogenic breast cancer tissues commonly contain a protein component the antigenic and physicochemical properties of which are similar to those of a protein component of murine mammary tumor virus. Advances in our understanding and control of human mammary carcinogenesis and biological behavior are dependent on the clinicopathological characterization of individual patients and their breast tissues as well as on the analytical procedures used.
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PMID:Biological considerations of tumor-specific and virus-associated antigens of human breast cancers. 17 36

The effects of long-term administration of nafenopin, a potent hypolipidemic drug with marked hepatomegalic and peroxisome-proliferative properties, were studied in wild-type (Csa strain) and acatalasemic (Csb strain) mice. Nafenopin was administered in the diet at a concentration of 0.1% during the first 12 months and then at 0.05% until the termination of the experiment at 20 months. By 56 weeks, 100% mortality occurred in both male and female wild-type mice, whereas the mortality rate in acatalasemic mice was approximately 50%. Between 18 and 20 months of the experiment, 9 of 9 male and 12 of 12 female acatalasemic mice that survived chronic nafenopin treatment developed hepatocellular carcinomas, some of which metastasized to the lungs. None of the 15 male and 15 female acatalasemic controls developed liver cancers. Numerous peroxisomes were seen in the lung metastases of these hepatocellular carcinomas on electron microscopic examination; in contrast the number of peroxisomes in primary liver tumor cells varied considerably. The hepatocarcinogenicity of nafenopin strongly suggests the need for long-term studies with other hypolipidemic drugs that cause hepatomegaly and peroxisome proliferation to clarify the role, if any, of peroxisome proliferation in liver carcinogenesis.
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PMID:Hepatocellular carcinomas in acatalasemic mice treated with nafenopin, a hypolipidemic peroxisome proliferator. 17 2

The study of viral antibodies in 6714 sera demonstrated that the level of antibodies to infectious viruses was the same in cancer patients as in controls. However, the patients with various forms of neoplasia showed a considerable percentage and high antibody levels to viruses with oncogenic potential for animals (adenovirus, SV40, Rous virus) or involved in human carcinogenesis (herpes virus).
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PMID:Studies on the presence of viral antibodies in patients with various forms of malignant neoplasia. 17 91

Four simultaneous dosages of the ethylnitrosourea precursors, ethylurea and sodium nitrite, were administered intragastrically to pregnant hamsters at 100 mg/kg and 50 mg/kg respectively, from the 12-15th days of pregnancy. The treatment induced multiple neurogenic tumors of the peripheral nervous system in the offspring. Female progeny developed a greater incidence and multiplicity of peripheral nervous system tumors with significantly shorter latencies than males, thus establishing evidence that the tumors were age and sex dependent. The tumors presented varied morphological patterns and upon transplantation, grew regularly, exhibiting their malignant nature. The possible influence of estrogenic hormones on the development and growth of peripheral nervous system tumors and comparative aspects of the relationship between prenatal and postnatal carcinogenesis with regard to the ensuing tumor spectra as a consequence of exposure to the same chemical agent, are discussed.
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PMID:Transplacental effects of ethylnitrosourea precursors ethylurea and sodium nitrite in hamsters. 17 12


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