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Biomedical subjects

F L Meyskens

Publications and source records attributed to F L Meyskens.

At least 109 records · Page 6Linked to original sources
PubMed1989

Hispanics and cancer preventive behavior: the development of a behavioral model and its policy implications.

This paper presents the theoretical development of a model that predicts the conditions under which Hispanics will seek preventive health care. Research trends, however, show that Hispanics tend to delay preventive care, resulting in higher morbidity and mortality rates for serious diseases such as cancer. Since many serious diseases, such as heart disease, diabetes and cancer can be prevented or treated more effectively if detected early, it is crucial to understand the motivating forces behind Hispanics' preventive health behavior. The Hispanic model, which is an extension of the Health Behavior in Cancer Prevention Model developed by Atwood (1986), includes as core variables environmental barriers to access and English language proficiency, as well as social support, health beliefs, self-efficacy, or perceived skill, health locus of control, and health values. The practical health policy applications of the model are also discussed.

Attitude to Health↗
PubMed1989

Chromosome alterations in human malignant melanoma.

This review has provided an update on current progress in identifying recurring sites of chromosome change in human malignant melanoma. Despite methodologic difficulties, a recurring and decidedly nonrandom pattern of chromosome change is beginning to emerge for this neoplasia. It appears most reasonable to suggest that as an increasing number of cases of melanoma are cytogenetically examined, the stratification of patients into defined subgroups based upon specific chromosome abnormalities will be possible. At present, the clinical utility of chromosome analysis in malignant melanoma is indeterminate. However, the pinpointing of regions of the genome which are characteristically altered in this tumor may be of significant benefit in targeting future molecular (and hopefully mechanistic) investigations. Continued study of the basic genetics of malignant melanoma would appear a particularly fruitful avenue to continue and it assuredly will add to our understanding of the causation, progression, and ultimately the control of this disorder.

Chromosome Aberrations↗
PubMed1988

Cutaneous malignant melanoma (Arizona Cancer Center experience). I. Natural history and prognostic factors influencing survival in patients with stage I disease.

The authors have studied the natural history of 377 patients with Stage I cutaneous malignant melanoma followed at the Arizona Cancer Center, Tucson. Two hundred eight patients, or 55%, remained free of metastatic disease after a median follow-up of 30 months. The survival at 5, 8, and 10 years was 69, 65, and 63%, respectively. Natural breakpoints in Breslow thickness for survival occurred at 0.85, 1.95, and 4.00 mm. These are not significantly different from those found by other investigators. A step-down multivariate analysis using the Cox regression model yielded four factors as highly significant in predicting survival: Breslow thickness (P less than 0.001), an age/sex interaction (P = 0.0012), clinical ulceration (P = 0.0039), and a prophylactic node dissection (P = 0.019). No predictive value for a BANS or non-BANS location was detected. These results are discussed in reference to other large series which describe the natural history of cutaneous melanoma.

Arizona↗
PubMed1988

Treatment of advanced squamous cell carcinoma of the head and neck with isotretinoin: a phase II randomized trial.

Retinoids, the analogs of vitamin A, are active in vitro and in vivo against squamous cell carcinoma in animals and against certain epithelial precancers and cancers in humans. These data led us to design a prospective, multi-institutional, randomized phase II trial of isotretinoin in advanced head and neck squamous cell carcinoma. We randomly assigned 40 patients to receive isotretinoin or methotrexate, the best-studied and most active single agent for this disease. Overall, the study patients had extremely poor prognoses, i.e., low performance statuses and recurring disease after surgery and/or irradiation. Three objective responses (16%), including one complete response, occurred in the 19 evaluable isotretinoin-treated patients. Only one minor response (5%) occurred in the methotrexate-treated group. Toxicity occurred with both drugs, but was manageable and never life threatening in the retinoid group. These results and the established activity of retinoids in oral leukoplakia (a precursor of head and neck cancer) indicate the need for further study of this class of drugs in head and neck cancer.

Adult↗
PubMed1988

Radiation survival of murine and human melanoma cells utilizing two assay systems: monolayer and soft agar.

The radiation response of murine and human melanoma cells assayed in bilayer soft agar and monolayer was examined. Cells from the murine melanoma Cloudman S91 CCL 53.1 cell line and three human melanoma cell strains (C8146C, C8161, and R83-4) developed in our laboratory were irradiated by single dose X-rays and plated either in agar or on plastic. D0 values were the same within 95% confidence intervals for cells from the human melanoma cell strains C8146C, C8161, and R83-4 but were dissimilar for the murine cell line CCL 53.1 Dq values were different for all cells studied. The shape of the survival curve for all four melanomas was not identical for cells assayed in soft agar versus cells grown on plastic. This would indicate that apparent radiosensitivity was influenced by the method of assay although there were no apparent consistent differences between the curves generated by monolayer or bilayer soft agar assays.

Animals↗
PubMed1988

Vitamin A derivatives in the prevention and treatment of human cancer.

Vitamin A is essential for normal cellular growth and differentiation. A vast amount of laboratory data have clearly demonstrated the potent antiproliferative and differentiation-inducing effects of vitamin A and the synthetic analogues (retinoids). Recent in-vitro work has led to the exciting proposal that protein kinase-C may be centrally involved in many of retinoids' anticancer actions including the effects on ornithine decarboxylase induction, intracellular polyamine levels, and epidermal growth factor receptor number. Several intervention trials have clearly indicated that natural vitamin A at clinically tolerable doses has only limited activity against human neoplastic processes. Therefore, clinical work has focused on the synthetic derivatives with higher therapeutic indexes. In human cancer prevention, retinoids have been most effective for skin diseases, including actinic keratosis, keratoacanthoma, epidermodysplasia verruciformis, dysplastic nevus syndrome, and basal cell carcinoma. Several noncutaneous premaligancies, however, are currently receiving more attention in retinoid trials. Definite retinoid activity has been documented in oral leukoplakia, laryngeal papillomatosis, superficial bladder carcinoma, cervical dysplasia, bronchial metaplasia, and preleukemia. Significant therapeutic advances are also occurring with this class of drugs in some drug-resistant malignancies and several others that have become refractory, including advanced basal cell cancer, mycosis fungoides, melanoma, acute promyelocytic leukemia, and squamous cell carcinoma of the skin and of the head and neck. This report comprehensively presents the clinical data using retinoids as anticancer agents in human premalignant disorders and outlines the ongoing and planned studies with retinoids in combination and adjuvant therapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1988

Nonsurgical treatments for skin cancer: retinoids and alpha-interferon.

Retinoids, the natural and synthetic analogs of vitamin A, and alpha-interferon have been used effectively in the treatment of certain cutaneous premalignancies and malignancies. Retinoids have shown impressive activity against premalignant disorders of the skin (actinic keratoses, keratoacanthoma, epidermodysplasia verruciformis) and of other epithelial sites (oral leukoplakia, cervical dysplasia). In established basal cell skin cancers, topical retinoid treatment has produced a complete response rate of 33%, and systemic retinoids have produced an objective response rate of 51%. In advanced squamous cell skin cancers, systemic retinoids have produced a response rate of over 70%. Intralesional alpha-interferon has produced impressive responses and systemic alpha-interferon has produced a 50% objective response rate in basal and squamous cell carcinoma. Retinoid therapy and alpha-interferon have produced modest overall results in melanoma, although striking individual responses have been reported. In cutaneous T-cell lymphoma, which is notably refractory to chemotherapy, retinoids and alpha-interferon have produced responses in 60%+ and 70%+ of cases, respectively. Retinoids and alpha-interferon, either alone or in combination, offer exciting prospects for primary and neoadjuvant therapy for advanced malignancy. Retinoids also show promise as relatively nontoxic preventive and adjuvant therapy. Researchers should focus on integrating these drugs with other biological response modifiers, differentiation agents, and cytotoxic drugs for treating advanced malignancy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1988

Human recombinant alpha- and gamma-interferons enhance the cytotoxic properties of tumor necrosis factor on human melanoma.

Three short-term human melanoma cell lines were tested for sensitivity to human recombinant alpha-tumor necrosis factor (TNF) in a semisolid agar colony formation assay. Cells from three pigmented and one amelanotic strain displayed low sensitivity to TNF. The ID50 for the inhibition of melanoma colony formation ranged from 2,500 to 20,000 U/ml. We then tested the ability of human recombinant alpha-interferon (IFN-alpha) and gamma-interferon (IFN-gamma) to interact with TNF to inhibit melanoma colony formation. Analysis of the TNF-IFN mixtures using the median effect method demonstrated that both IFNs interacted synergistically with TNF to inhibit melanoma colony formation. On a unit basis, IFN-gamma was more active with TNF than IFN-alpha. The addition of the second interferon to the mixture enhanced the ability of TNF to promote the cytolysis of human melanoma cells. The enhanced killing effect seen with the combination of IFN-alpha, IFN-gamma, and TNF suggests an interesting strategy for the treatment of human melanoma.

Cell Survival↗
PubMed1988

A phase I trial of recombinant interferon-alpha and alpha-difluoromethylornithine in metastatic melanoma.

Both interferon-alpha (IFN-alpha) and alpha-difluoromethylornithine (DFMO) have shown modest activity as single-agent therapy in the treatment of malignant melanoma. Several investigators have demonstrated true synergism in vitro of the combination of DFMO and IFN-alpha against human tumor cells, including melanoma. We have investigated this combination in 17 patients with malignant melanoma in a Phase I trial. Patients were treated with 4 or 6 g/m2/day of oral DFMO in 3 divided doses for 11 days, followed by a 3-day rest period. Concomitant administration of 1.5, 3.0, 6.0 or 9.0 x 10(6) U/m2 IFN-alpha intramuscularly was given. The maximum tolerated dose was 4 g/m2/day of DFMO plus 6 x 10(6) U/m2/day of IFN-alpha. Dose-limiting toxicity occurred in 3 of 3 patients receiving 9 x 10(6) U/m2 IFN-alpha and consisted of leukopenia, fatigue, and weight loss. Other toxicities were mild and included reversible hearing loss, diarrhea, nausea, and vomiting. Three responses were seen, including one partial response (PR) of soft tissue metastases, one PR of lung and liver, and one complete response of liver metastases without clearance of carcinomatous meningitis. A Phase II trial has been initiated based on these encouraging results.

Adult↗
PubMed1987

Rationale and strategies for chemoprevention of cancer in humans.

The potential for chemical intervention (chemoprevention) as a means of halting or delaying the process of carcinogenesis is assessed as a strategy for reducing the incidence of human cancer. The process of carcinogenesis is dissected into its constituent steps, thereby exposing sites for intervention. These sites are then critically discussed with regard to the existence of chemicals active at these sites using data gained from the laboratory and from epidemiological studies, intrinsic problems or advantages associated with intervention at specific sites in the carcinogenic process, and practical aspects of intervention in humans. The design and potential long-term positive and negative consequences of chemoprevention clinical trials are critically discussed, with the objective of exposing the major differences that exist between clinical trials in cancer chemoprevention and those in cancer chemotherapy. Results of completed prevention trials and details of ongoing trials are presented and discussed. Based on the laboratory, epidemiological, and clinical evidence presented, it is concluded that chemoprevention offers excellent prospects as a means of reducing cancer incidence. Among currently available agents, the retinoids possess the best combination of properties. However, much more research is needed to optimize drugs and protocols and to develop interim end points for assessing response. The authors finally caution that overambitious claims for the prospects for chemoprevention may lead to reduced emphasis on the need for changes in life-style (principally in smoking and diet) that are viewed as having the greatest potential for reducing cancer incidence.

Anti-Inflammatory Agents↗
PubMed1987

Tetrazolium staining by optical scanning overestimates colony size and number of colonies counted.

We measured the effect that staining with 2-(P-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride (INT) had on the number and size distribution of tumor colonies counted using an optical image analyzer (FAS II). Staining increased the number of tumor colonies counted. By using opaque tumor cells or pigmented melanoma cells and measuring colony growth kinetics, we demonstrated that the use of INT staining to assist in counting tumor colonies artificially increased the size of viable tumor cell aggregates by adding a red precipitate to the outside surface of the cells. Laboratories that are using the INT method for drug screening are probably measuring colonies down to and below 42 microns in diameter. These small colonies could result from as few as one or two divisions. Thus, potentially useful drugs may be missed in the screen because of the presence of abortive colonies: i.e., lethally damaged cells completing only one or two divisions.

Cell Count↗