Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The occurrence of squamous cell carcinoma of the lid is reviewed with emphasis upon the incidence, clinical presentation, pathophysiology and methods of treatment. Squamous cell carcinoma accounts for about 9% of all eyelid malignancies, although it is frequently over-diagnosed by pathologists and confused histologically with other benign entities. This lesion occurs most commonly in elderly, fair-complexioned individuals with a history of chronic sun exposure and skin damage. In the lids, squamous cell carcinoma shows a variety of clinical appearances although it usually presents as a painless, hyperkeratotic lesion that gradually enlarges and eventually ulcerates. There is a tendency for lower lid and lid margin involvement. This potentially lethal neoplasm is capable of aggressive local spread or metastasis to regional lymph nodes. The development of squamous cell carcinoma is thought to progress through phases of intraepithelial squamous dysplasia and intraepidermal squamous cell carcinoma before invasive squamous cell carcinoma occurs. Various treatment modalities have been advocated including surgical extirpation with histologic control, radiation therapy and cryotherapy.
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PMID:Squamous cell carcinoma of the eyelid. 352 6

Three cases of tricholemmal keratosis and two of tricholemmal carcinoma are reported. All patients were female and the age range was from 71 to 83 years. These rare tumors occur on the face and are obviously the result of long-standing actinic skin damage. Clinically, verrucous hyperkeratosis or cornu cutaneum (keratosis) are observed and in the case of tricholemmal carcinomas, ulcerated tumor nodules. Histologically pale, glycogen-rich polygonal cells with signs of tricholemmal keratinization without the presence of a granular cell layer are characteristic features. Tricholemmal keratoses exhibit no atypia or only a mild form; however, carcinoma in situ may occasionally develop. In contrast, tricholemmal carcinomas are characterized by increased pleomorphia, an increase in the rate of mitosis, and an invasive growth pattern. The prognosis is favourable.
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PMID:[Tricholemmal keratosis and tricholemmal cancer]. 365 4

Three hundred fifty albinos in the city of Dar-es-Salaam have been registered at the Tanzania Tumor Centre. Their skin changes were followed for at least 2 years. Chronic skin damage was evident in all albinos by the first year of life; by 20 years, the skin of every subject demonstrated subclinical malignant change, and some had clinical epitheliomas. Untreated, the latter tumors become intractable and disseminate, usually causing death in the third or fourth decade of life. Four clinical stages could be identified, each one associated with distinct pathologic changes: Stage 1, erythema; Stage 2, epidermal atrophy with dermal hypertrophy; Stage 3, solar keratosis; and Stage 4, clinical carcinoma (under 3 cm). It was found that clinical Stage 2 only occurs in those skin areas that show evidence of previous Stage 1 change. Similarly, Stage 3 occurs only in areas that have gone through Stages 1 and 2. Stage 4 cancers were only found in those areas that had gone through all of the three prior stages. During the 2-year period of this study, 104 skin cancers, both early and advanced, were recorded at the albino skin clinic. Thirty-three of the 104 cancers were advanced (over 4 cm in diameter). The median age of the latter group was 31.0 years. Whereas there was no sex bias in the distribution of clinical cancer, 28 of the 33 advanced cancers were in men. Histologically, the great majority of the advanced tumors were squamous cell carcinomas: 29 of 33. There was one melanoma and three basal cell tumors. The predominant site of advanced cancers in the study group was the head and neck region (30 patients); the other three occurred on the trunk, which is generally covered by clothes.
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PMID:The Tanzanian human albino skin. Natural history. 397 67

UV irradiation of mice causes a systemic immune alteration that can be detected either by suppression of the immunologic rejection of UV-induced tumors, or by suppression of contact hypersensitivity (CHS). Suppression of these two immunologic responses has similar photobiologic characteristics and in both cases is associated with the generation of antigen-specific suppressor T cells. To identify whether a specific photoreceptor for this effect exists, the relative wavelength effectiveness (action spectrum) was determined for the UV-induced suppression of CHS. Narrow bands of UV (half bandwidth 3 nm) were used at 10 wavelengths from 250 to 320 nm to obtain dose-response curves. Irradiation with each of these bands of UV caused dose-dependent immunosuppression of CHS, but with differing effectiveness. Immunosuppression was clearly separable from the generation of gross skin damage and inflammation. Further, immunosuppression by the most effective wavelength (270 nm) was associated with the generation of antigen-specific suppressor cells. The action spectrum derived from the dose-response curves has a maximum between 260 and 270 nm, a shoulder at 280-290 nm, and declines steadily to approximately 3% of maximum at 320 nm. The finding of such a clearly defined wavelength dependence implies the presence of a specific photoreceptor for this effect. Removing the stratum corneum by tape stripping before UV irradiation prevented the suppression of CHS using 254-nm radiation, suggesting the photoreceptor is superficially located in the skin. A number of epidermal compounds with absorption spectra similar to the action spectrum are discussed and evaluated with respect to their potential for being the photoreceptor. Based on (a) the close fit of its absorption spectrum to the action spectrum, (b) its superficial location in the stratum corneum, and (c) its photochemical properties, the hypothesis is advanced that the photoreceptor for systemic UV-induced immunosuppression of contact hypersensitivity may be urocanic acid. As such, it may also play a role in UV-induced carcinogenesis via the production of tumor-specific suppressor cells.
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PMID:Mechanism of immune suppression by ultraviolet irradiation in vivo. I. Evidence for the existence of a unique photoreceptor in skin and its role in photoimmunology. 3146 4

The radioprotective effect of 5-thio-D-glucose on mouse skin was studied. Intraperitoneal injection of A/J mice with 1.5 g/kg of 5-thio-D-glucose 2 hr prior to X irradiation of the foot reduced early foot skin damage through Day 40 postirradiation by a dose modification factor of 1.3 +/- 0.1. Similarly, late foot deformity during Days 60-90 postirradiation was reduced by a factor of 1.2 +/- 0.1. The radioprotective effect of 5-thio-D-glucose was also compared with that of WR-2721, an aminothiol radioprotector, in CDF1 mice. An intraperitoneal injection of 1.5 g/kg of 5-thio-D-glucose reduced early radiation-induced skin damage by a dose modification factor of 1.2 +/- 0.1 as compared to that of 1.5 +/- 0.2 by 0.65 g/kg of WR-2721 in this strain of mice. 5-Thio-D-glucose is also known to specifically kill and radiosensitize hypoxic tumor cells. Consequently, this drug may be a useful radiotherapy adjuvant, reducing normal tissue damage and enhancing tumor control by minimizing hypoxic protection.
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PMID:Skin radioprotection by 5-thio-D-glucose. 629 12

The persistence of the initiated state during two-step carcinogenesis in mouse epidermis is a generally accepted phenomenon, however, conflicting results exist with regard to the degree of irreversibility relative to the age of the animals. Several factors such as age-dependent alterations in the response of the epidermis to the promoter and skin damage following the initiation step have been proposed to account for the observed discrepancies. In the present investigation we have tried to circumvent skin-damaging effects of topically applied 7,12-dimethylbenz[a]anthracene by intragastric administration of the drug. Tumor production by topical promotion with 12-O-tetradecanoylphorbol-13-acetate was subsequently determined in 600 female NMRI mice using intervals of 4, 8, 16, 24, 32 and 40 weeks between initiation and promotion. Independent of the delay between the initiating and promoting step, we observed a similar time course and extent of tumor production in the different experimental groups. This indirectly proves that the promoting capacity of 12-O-tetradecanoylphorbol-13-acetate is age-independent and that during aging no substantial loss of initiated cells occurs in mouse epidermis.
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PMID:On the persistence of tumor initiation in two-stage carcinogenesis on mouse skin. 640 73

The radiosensitizing effect of misonidazole is dose dependent, so theoretically it would be desirable to use as large a dose as possible. However, clinical studies have indicated a maximum tolerable dose restricting the effects of misonidazole in patients. We injected misonidazole directly into tumor tissues in combination with irradiation in an attempt to obtain a sufficiently high concentration in tumors while maintaining a low level in the blood. Concentration of the drug in tumor tissues was confirmed to be high by examination of the resected low-grade chondrosarcoma into which the drug had been locally injected prior to the operation. Blood levels were confirmed to be significantly low. Seventeen patients were treated with local injections of the drug, each with radiotherapy. All patients either had advanced tumors, or were in the terminal stage after repeated radiotherapy and chemotherapy. A relatively high radiation dose per fraction was used. Complete response was obtained in eight patients (47%) and partial response in four (24%). No change was observed in three patients (18%) while two (12%) exhibited progressive disease. In the seven patients with multiple metastatic lesions, the response of the tumors treated with this method were compared to that of the tumors treated by radiation alone in the same patient. The sensitizing effect of the drug was clearly observed in three out of seven patients. No toxicities in the nervous system or in the gastrointestinal system were observed, and no local skin damage by the injections was seen. Local injections of misonidazole were shown to have a significant radiosensitizing effect without any side effects. The combined treatment of radiation and local injections of misonidazole is considered to be a promising new treatment method.
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PMID:Combined treatment of radiation and local injections of misonidazole. 651 31

The effect of the protein synthesis inhibitor cycloheximide (CHM) on normal tissue tolerance and tumor control in the rat following single doses of radiation has been studied. We have previously shown that the drug protects against skin damage when administered prior to irradiation of the hind limbs. It does not protect against six-month lethality when given prior to irradiation of the kidneys. In the present studies protection of rat bone marrow as evidenced by 30-day lethality was observed when CHM was given prior to whole-body irradiation. When CHM was given to rats bearing the BA1112 tumor, it had no protective effect on radiocurability. Therapeutically favorable differential protection of rapidly proliferating normal tissue over tumor can be achieved when CHM is administered prior to single radiation doses in the rat. This effect is most likely due to inhibition of protein synthesis and resultant interruption of the cell cycle in proliferating normal tissue. Further studies are required to determine the clinical applicability of CHM.
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PMID:Differential effect of cycloheximide on normal tissue tolerance and tumor control in irradiated rats. 674 49

Sunscreens containing 5-methoxypsoralen (5-MOP) are currently being marketed to promote tanning by inducing psoralen-mediated ultraviolet (UV) A (320-400 nm) melanogenesis. The rationale is that this may prevent UVB (290-320 nm) radiation-induced skin damage. However, mouse studies have shown that 5-MOP has the same cutaneous photocarcinogenic potential as 8-methoxypsoralen. In addition, the 5-MOP--containing sunscreen Sun System III (SS III), when combined with UVA, induces epidermal ornithine decarboxylase activity, an enzyme associated with tumor promotion. Therefore, we investigated whether SS III had sufficient psoralen concentration to be tumorigenic in hairless mice exposed to chronic, intermittent UVA radiation. SS III was applied to hairless mice 5 days per week for 20 weeks. After each application the mice were exposed to 2.5 to 10 joules/cm2 UVA radiation. All test groups developed atypical squamous papillomas in direct proportion to the dosage of UVA radiation received. A shorter latency period for tumor development was seen with larger UVA doses. Test animals followed up to 1 year developed invasive squamous cell tumors. Control groups (SS III without UVA and UVA without SS III) remained free of tumors. Animals receiving SS III plus UVA developed persistent skin thickening and increased dermal cyst formation similar to that reported with chronic exposure to UVB, a known carcinogenic wavelength. Over-the-counter sunscreens containing 5-MOP do contain sufficient psoralen concentrations to cause cutaneous phototoxicity and photocarcinogenicity in mice, and their use in humans should be discouraged in the interest of preventing further UV-induced skin damage and skin cancer.
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PMID:Psoralen-containing sunscreen is tumorigenic in hairless mice. 686 46

Following skin damage resulting from radiotherapy, pancancerous conditions, carcinomas and basal cell carcinomas not rarely pose therapeutic problems. We encountered those problems severally after radiotherapy of the middle face, for instance for lupus vulgaris or basal cell carcinoma. Senile skin changed over the years by climatological influences may create similar problems. Disorders of blood supply and lack of "tissue material" as consequences of radiation-induced skin atrophy are the reasons for the failure of many attempts of plastic surgery aimed at tumor removal and defect repair. Besides that, the conditions for such operative procedures are progressively deteriorating with the number of tumor recurrences. In these instances cryotherapy offers an excellent therapeutic alternative by virtue of the favorable healing tendency of the cryonecrosis including the final, inconspicuous scar formation.
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PMID:[Recurrent skin tumors following radiation injuries. Indication for cryotherapy]. 717 80


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