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Biomedical subjects

A M Markoe

Publications and source records attributed to A M Markoe.

At least 73 records · Page 4Linked to original sources
PubMed1986

Regression of posterior uveal malignant melanomas after cobalt plaque radiotherapy.

We reviewed the records of 17 patients with posterior uveal malignant melanoma who had been followed for at least 3 months prior to cobalt plaque radiotherapy and whose tumor had been documented to enlarge in thickness during that interval. We evaluated the relationship between the rates of pretreatment tumor enlargement and post-treatment tumor shrinkage using linear regression analysis. We found that the rate of postirradiation tumor shrinkage correlated strongly with the rate of preirradiation tumor enlargement regardless of whether the pretreatment rate of growth was slow, intermediate or rapid. We speculate that the more rapidly regressing tumors were more mitotically active than their more slowly regressing counterparts. If true, the survival rate of patients whose posterior uveal malignant melanomas regress rapidly following radiation therapy may prove to be worse than that of patients whose tumors regress slowly.

Brachytherapy↗
PubMed1986

Treatment of orbital pseudotumors and lymphoma.

Thirty-seven patients were identified in a retrospective review at Hahnemann University and Wills Eye Hospital; they had been treated for pseudotumor or lymphoma of the orbit and had adequate follow-up (x = 61.5 months). Overall, 31 of 37 patients (83.8%) were cleared of their orbital disease. Of the nine patients treated for lymphoma, all were cleared of disease in the orbit. Twenty-two of 28 patients (78.6%) with benign disease were likewise cleared of orbital disease. Ten of 10 patients who received radiation as their initial therapy were cleared. Overall, 17 of 20 (85%) of patients who received radiation as part of their therapy were cleared of orbital disease, with mean dosages of 2,166 cGy (1 cGy = 1 rad) for benign disease and 3,547 cGy for lymphoma. Brief representative case studies and a review of the literature are presented. Two patients with benign disease were cured of disease in the orbit but went on to develop systemic lymphoma. Radiation therapy plays an essential role in the management of patients with orbital lymphomatous diseases.

Adolescent↗
PubMed1986

Cancer cure with organ preservation using radiation therapy.

In 1985, the American Cancer Society has anticipated that 910,000 new cases of invasive cancer will be diagnosed in the United States. More than 37% of those patients can be treated for cure with organ preservation using radiation therapy. The basic biologic background for such an approach to the problem is well established. Clinical data to substantiate the validity of the concept date from 1902 to the present. Without question, organ preservation is becoming a major and important concept in the management of the patient with cancer, and new and innovative techniques for treatment are enabling the organ to be preserved, the cancer to be cured, and appropriate cosmesis and function to be preserved. Many tumor sites are appropriate for this treatment technique, including the breast, the eye, the larynx, and the prostate. In 1985, there has been new emphasis on the successful treatment of cancer with the preservation of the organ intact. The maxim to offer the patient the maximum potential for cure with the minimum complication now has an additional concept related to the opportunity to preserve cosmesis and function.

Breast Neoplasms↗
PubMed1986

Radiation therapy in the elderly patient.

In the management of cancer in the older patient, the treatment program designed should be based on careful analysis of the patient's problem and a decision made as to whether the patient can be cured by the radiation therapy technique for what is primarily a limited local regional disease process or palliated by virtue of the fact that the patient has more widespread disseminated disease. In both instances, careful attention must be given to proper, continuous and careful support of all the problems the older patient has. The patient's status may dictate a major change in the radiation therapy program by virtue of fractionation, protraction, total dose being delivered or even the volume being treated. The response to treatment in terms of normal tissue effects require careful medical management in order to minimize those effects. Interruptions of treatment should be allowed only if appropriate deliberate management of side effects are not effective. The basic principle in the management of the older patient with cancer is to allow for cure of those patients in which that is a reasonable possibility with the minimum in terms of complication as a consequence of the treatment program. Palliative radiation therapy programs are directed toward improvement in the quality of life by diminishing symptoms and hastening rehabilitation. When two definitive treatment programs, surgery or radiation therapy, have equal probability for long-term survival, the radiation therapy curatively administered would allow for the preservation of anatomy and function. The maximum potential for management in the older patient with cancer is achieved best in the circumstances of an integrated multimodal team for management including those specialists that are appropriate to the disease process being treated. These would include the surgeon, the radiation oncologist, the medical oncologist, the pathologist, the diagnostic radiologist, as well as other specialists such as anesthesiology, rehabilitation medicine, etc., along with paramedical support members of the team. It is within this environment that the maximum potentials of treatment can be achieved.

Aged↗
PubMed1985

Radiation oncology. Programs for the present and future.

Radiation oncology in 1984 continues to make major advances in the multidisciplinary clinical programs. This has been possible by virtue of the radiation oncologist, who is an active participant in these clinical programs. The changing role for the radiation oncologist has dictated a greater participation in the primary management of the patient's disease process and also participation in multidisciplinary research programs.

Breast Neoplasms↗
PubMed1985

Choroidal melanoma: comparison of CT, fundoscopy, and US.

Computed tomography (CT) was compared with fundoscopy and ultrasound (US) in 62 patients with primary choroidal melanoma. All lesions were detected with CT and fundoscopy and all but one with US. Of five cases of extrascleral extension, four were identified with CT and fundoscopy and two with US. CT best depicted the extent of retrobulbar tumor. Tumor thickness was best evaluated with CT, with good correlation between CT and US. Tumor enhancement was noted in all 51 patients who had both noncontrast and contrast CT. Because of its higher density, tumor could be distinguished from retinal detachment on CT scans in most cases.

Adult↗
PubMed1985

Malignant melanoma of the eye: treatment of posterior uveal lesions by Co-60 plaque radiotherapy versus enucleation.

Survival rates and visual acuity of 100 patients treated for posterior uveal malignant melanoma by cobalt-60 plaque radiotherapy were compared with 150 patients treated by enucleation for the same disease. Life-table comparisons of the entire group showed significant differences in survival rates, with plaque radiotherapy patients appearing to fare better. However, when patients with small or medium tumors were compared, only slight differences were seen, implying that criteria used to select patients for treatment may affect interpretation. The two groups were also compared using the Cox proportional hazards model, which predicts survival based on the impact of clinical variables. In this analysis, the survival rates of the plaque radiotherapy group were no worse than those of the enucleation group. The advantage of conservative therapy lies in the potential to preserve useful vision over a considerable time. Because patients were specifically selected for treatment modality and because the study size used to calibrate the Cox model was small, the results of this study must be interpreted with caution.

Cobalt Radioisotopes↗
PubMed1984

Regression of posterior uveal melanomas following cobalt-60 plaque radiotherapy.

A method has been devised for evaluating the rate and extent of regression of the first 100 consecutive patients with a posterior uveal melanoma that we had managed by Cobalt-60 plaque radiotherapy at Wills Eye Hospital. It was found that the "average" posterior uveal melanoma in the series did not regress rapidly to a flat, depigmented scar but shrank slowly and persisted as a residual mass approximately 50% of the thickness of the original tumor at 54 months following Cobalt-60 plaque radiotherapy. We also found that the rate and extent of regression of the tumors in patients who subsequently developed metastatic melanoma were not appreciably different than the rate and extent of regression of the tumors in patients who remained well systemically. These observations indicate that the rate and extent of regression of posterior uveal melanomas following Cobalt-60 plaque radiotherapy are poor indicators of the prognosis of the affected patients for subsequent development of clinical metastatic disease.

Brachytherapy↗
PubMed1980

Tissue distribution and retention of 5-thio-D-glucose in animal tumor models.

5-Thio-D-glucose (5-TDG) has demonstrated potential as a radiation sensitizer for hypoxic cells growing in monolayer culture and as multicell spheroids. We have studied the biodistribution and pharmacokinetics of radiolabeled (35S or 3H) 5-TDG prior to utilizing this bioisotere of D-glucose for radiation sensitization studies in vivo. At all times after administration, 5-TDG achieved higher tissue levels of radioactivity in hamster pancreatic tumors of ductal and acinar cell origin than in the normal pancreas. By 2 hours after intravenous injection, the duct tumor activity concentration exceeded that of any other tissue; a similar situation obtained after 4 hours in the acinar tumor model. However, the functioning insulinoma model exhibited similar radioactivity uptake and kinetics as did normal pancreas. In all models, metastases behaved similarly to the primary transplanted tumor in terms of uptake and retention of radioactivity. Addition of carrier 5-TDG appeared to abrogate much of the selective uptake of label into tumor relative to normal tissue, in terms of % dose/g tissue, but the total uptake into tumor was greater. The drug is rapidly excreted in the urine and the nature of this excretion was examined. Retention of activity in normal lung tissue was similar to that of pancreatic tumors and prompted a study of uptake into Lewis lung carcinoma. Again, tumor uptake in % dose/g approximated uptake into normal lung tissue, but total uptake into tumor was greater. These studies provided the basis for initiation of in vivo studies of potential cytotoxic and radiation-potentiating activity of 5-TDG.

Adenocarcinoma↗
PubMed1979

Biodistribution and pharmacokinetics of S-35-labeled 5-thio-D-glucose in hamsters bearing pancreatic tumors.

5-thio-D-glucose (5-TDG) exerts profound effects on rapidly metabolizing tissues. We have used liquid scintillation counting to study the tissue distribution and pharmacokinetics of S-35-labeled 5-TDG in hamster models of pancreatic tumors. In the normal hamster, initial uptake of S-35 activity into kidney, liver, and blood was high, but rapidly decreased with time. The pancreatic uptake (% dose/g) never exceeded 0.75%. This level occurred only at the earliest times after administration. Uptake in all three tumor models exceeded that in pancreatic tissue within 15 min of injection. The highest tumor-to-pancreas ratio was seen in the duct-tumor model, which also exhibited the most favorable tumor-to-tissue ratio when compared with kidney, liver and muscle. Favorable ratios were most pronounced at 6 and 24 hr after injection. These studies provide impetus for the use of 5-TDG as a model compound for the synthesis of potentially useful agents for clinical detection of pancreatic tumors.

Adenocarcinoma↗
PubMed1979

The biologic basis for combined modality treatment of cancer.

Strategies related to cancer should be aimed at optimization of local and regional treatment. Delineation of subsets of patients with high risk for recurrence would have a significant impact, upon which such adjunctive systems of therapeutic management should be evaluated. In disseminated disease, or where the probability of dissemination is high, evaluation of any realistic potential combination of treatment for tumor control should be pursued. It is necessary to delineate optimal palliative therapy where tumor control is not possible, but also to test new drugs, immunotherapeutic tools and combination regimens in all such situations where the disseminated compartment of the disease is of high probability. Only under such circumstances will the most practical and important optimization of treatment programs be achieved. The development of the above basic attributes for each tumor type needs to be studied so that protocols can be developed with a clear understanding of the nature of the disease, condition to be studied, and the general therapeutic strategies to be followed.

Antineoplastic Agents↗
PubMed1976

Estimation of tumor growth fraction in murine tumors by the primer-available DNA-dependent DNA polymerase assay.

The tumor growth fraction measured by the percentage labeled mitoses method has been determined in transplantable solid and ascites murine tumors, the latter being measured at different times after transplantation. These values were compared to an in vitro, autoradiographic assay that determines the fraction of cells in a given population (primer-available DNA-dependent DNA polymerase index) that have both nuclear DNA-dependent DNA polymerase and DNA capable of acting as primer-template. It appears that almost all cells with a short G1 phase duration (less than 19 hr) that are within the proliferative cycle are primer-available DNA-dependent DNA polymerase positive. The results of the comparison indicate that the primer-available DNA-dependent DNA polymerase index estimation of growth fraction is very nearly identical to the growth fraction measured by the percentage labeled mitoses method.

Animals↗