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Dive into the research topics where John W. Gamel is active.

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Featured researches published by John W. Gamel.


American Journal of Ophthalmology | 1983

Modifications of Callender's Classification of Uveal Melanoma at the Armed Forces Institute of Pathology

Ian W. McLean; Walter D. Foster; Lorenz E. Zimmerman; John W. Gamel

One hundred well-documented cases of uveal melanoma accessioned at the Armed Forces Institute of Pathology before 1970 were reviewed and reclassified to identify changes made in the Callender classification. We compared the new classification with the original classification to determine the effect of the changes on the prediction of outcome for the patient after enucleation. Staff pathologists had originally classified 52 of the 100 cases as spindle-cell type melanoma. Only 31 of the 100 cases were reclassified as spindle-cell types (two spindle-cell nevi and 29 spindle-cell melanomas). Tumors classified as mixed-cell type were further subdivided into groups based on the percentage and size of the epithelioid cells. Tumors formerly classified as spindle-cell type that contained small or rare epithelioid cells were reclassified as mixed-cell type. This improved the prediction of outcome for the patient. We found that nucleolar size and pleomorphism are important variables that should be considered in the classification of uveal melanomas.


Ophthalmology | 1991

Impact of Local Tumor Relapse on Patient Survival after Cobalt 60 Plaque Radiotherapy

Tamara R. Vrabec; James J. Augsburger; John W. Gamel; Luther W. Brady; Carlos Hernandez; Reginald Woodleigh

The authors investigated the impact of local intraocular tumor relapse on survival in a matched-group comparison study of patients with primary choroidal or ciliary body melanoma managed with cobalt 60 plaque radiotherapy. Sixty-two patients with local relapse were matched with an equal number of relapse-free patients in terms of known clinical prognostic factors for both melanoma-specific mortality (largest linear tumor dimension, location of anterior tumor margin, age) and local tumor relapse (location of posterior tumor margin). The follow-up of every relapse-free patient equaled or exceeded the interval to relapse for each matched patient with local relapse. The estimated 5-year survival (Kaplan-Meier) in the relapse-free patients was 87% (standard error = 4%), while that in the local relapse group was 58% (standard error = 6%). This difference is statistically significant (P less than 0.0001, log rank test). These results support the hypothesis that local tumor relapse after cobalt 60 plaque radiotherapy is an important post-treatment clinical indicator of the tumors greater malignant potential and the patients increased risk of melanoma-specific mortality.


Cancer | 1990

Clinical prognostic factors in patients with posterior uveal malignant melanoma

James J. Augsburger; John W. Gamel

The authors evaluated the prognostic value of clinically assessed variables for predicting length of survival until death from metastatic disease in 237 patients with a primary choroidal or ciliary body melanoma. Using multivariate Cox proportional hazards modeling, the authors identified the largest linear basal tumor diameter (mm), estimated by indirect ophthalmoscopy and fundus drawing, the location of the anterior margin of the tumor relative to the ocular equator and ora serrata, and the age of the patient at the time of treatment as the best combination of the clinically assessed variables for predicting survival. For each patient in this group, the authors computed a prognostic index based on the best multivariate Cox model. They showed that patients with low, intermediate, and high values of prognostic index had low, intermediate, and high melanoma‐related mortality rates, respectively, during the first 5 to 8 posttreatment years. These results suggest that: (1) clinically assessed variables evaluated according to a standardized protocol are useful for predicting the survival of treated patients with posterior uveal melanoma and (2) ophthalmologists who assess potential clinical prognostic variables consistently may identify subgroups of patients with comparable mortality risk on the basis of noninvasive testing.


Cancer | 1993

Biologic distinctions between cure and time to death in 2892 patients with intraocular melanoma

John W. Gamel; Ian W. McLean; Jeff B. McCurdy

Background. For certain types of cancer, resection alone rarely achieves a cure, but patients nevertheless tend to have a prolonged survival before they die of the tumor. For other types of cancer, the opposite scenario prevails, suggesting that those biologic mechanisms that allow a curative resection are not identical to those that determine survival time among uncured patients.


British Journal of Ophthalmology | 1989

Clinical parameters predictive of enlargement of melanocytic choroidal lesions.

James J. Augsburger; Robert P. Schroeder; Carla Territo; John W. Gamel; Jerry A. Shields

The authors followed up 197 melanotic choroidal lesions (62 categorised as benign naevi, 76 classified as suspicious naevi, 41 diagnosed as dormant melanomas, and 18 categorised as active melanomas) left untreated after their initial clinical documentation. Thirty-nine of these lesions enlarged during a five-year follow-up interval (cumulative proportion of lesions that enlarged = 26.2% by Kaplan-Meier method). Individual clinical parameters predictive of lesion enlargement (p less than 0.01) included larger size of the lesion, especially lesion thickness, presence of retinal detachment, location of the lesions posterior margin within 2 disc diameters of the optic disc, presence of symptoms, and presence of orange pigment clumps on the lesions surface. The best combination of these parameters for prediction of lesion enlargement, as identified by multivariate Cox regression analysis, consisted of thickness of the lesion, retinal detachment, and symptoms. The five-year incidence of lesion enlargement for patients with none of these prognostic parameters was 5.8%, while that for patients with all three unfavourable parameters simultaneously was 90.6%.


Human Pathology | 1982

Computerized histologic assessment of malignant potential: A method for determining the prognosis of uveal melanomas

John W. Gamel; Ian W. McLean; Richard A. Greenberg; Lorenz E. Zimmerman; Steven J. Lichtenstein

The authors evaluated 50 cases of primary melanoma of the choroid and ciliary body. In each case, 100 cells were randomly selected from a single histologic slide, and on each cell computer-assisted measurements were made of 18 nuclear and nucleolar features. Means and standard deviations were calculated for each of these features in each tumor. Thirteen calculated variables (six means and seven standard deviations) were found to correlate significantly with patient mortality following enucleation. Standard deviations of statistically significant nuclear and nucleolar features demonstrated significantly greater correlation with mortality than the means of these features, thus confirming the great value of nuclear pleomorphism for predicting the malignant potential of uveal melanomas. Furthermore, when the standard deviation of the nucleolar circumference, a feature highly correlated with survival (P less than 0.00001), was combined with the measurement of the largest dimension of the tumor, linear discriminant analysis correctly predicted the clinical course of 88 per cent of cases.


American Journal of Ophthalmology | 1990

Cobalt-60 plaque radiotherapy vs enucleation for posterior uveal melanoma

James J. Augsburger; John W. Gamel; Kyra Lauritzen; Luther W. Brady

We compared the survival of 302 patients with a primary choroidal or ciliary body melanoma treated by cobalt-60 plaque radiotherapy between 1976 and 1982 with the survival of 134 patients treated by enucleation during the same period. Tumor size, location of the anterior margin of the tumor, and patient age at the time of treatment were identified as simultaneous significant clinical variables for predicting melanoma-specific mortality by multivariate Cox proportional hazards modeling. We computed a prognostic index for each patient based on this model and found that patients in the enucleation group had slightly higher values of this index than did patients in the cobalt-60 plaque radiotherapy group. Risk ratios for the treatment effect computed from a Cox model incorporating prognostic index and the treatment variable were found to be approximately equal to 1, both for analysis of melanoma-specific mortality and total mortality. These results indicate that when one controls for differences in prognostic index between the groups, cobalt-60 plaque therapy and enucleation are essentially equivalent in their effect on survival.


Ophthalmology | 1987

Post-irradiation Regression of Choroidal Melanomas as a Risk Factor for Death from Metastatic Disease

James J. Augsburger; John W. Gamel; Jerry A. Shields; Arnold M. Markoe; Luther W. Brady

To determine the prognostic value of the regression rate of choroidal melanomas after cobalt-60 plaque radiotherapy, the authors performed a multivariate analysis on 159 patients treated with a cobalt plaque during the interval from 1976 through 1980. Thirty-three of the 159 patients had died as of the survey date; 29 of metastatic melanoma and 4 of other causes. Multivariate Cox proportional hazards modeling identified a two-term regression incorporating maximal basal tumor diameter at treatment and tumor thickness at 12 months posttreatment as the best model (P less than 0.005 for both parameters) for predicting length of tumor-free survival. These results are consistent with the hypothesis that rapid regression of a choroidal melanoma after cobalt-60 plaque radiotherapy is an unfavorable prognostic sign for prolonged metastasis-free survival.


American Journal of Ophthalmology | 1980

Acute Ischemic Optic Neuropathy in Severe Preeclampsia

Roy W. Beck; John W. Gamel; Robin J. Willcourt; Gerald Berman

A 32-year-old woman developed bilateral blindness along with severe preeclampsia of pregnancy. Ophthalmoscopic examination disclosed chalky-white optic disks with only minimal changes in the retinal vasculature. After caesarean section, the preeclampsia improved, and complete return of visual acuity occurred during a three-day period. Blindness has rarely been reported as a complication of preeclampsia. In almost all cases it has been associated with severe compromise of the retinal vasculature. conversely, the ophthalmoscopic findings in our case strongly support acute ischemic optic neuropathy as the cause of blindness.


Cancer | 1996

The impact of stage and histology on the long-term clinical course of 163,808 patients with breast carcinoma

John W. Gamel; John S. Meyer; Eric J. Feuer; Barry A. Miller

Stage and histologic type have a significant impact on the long term clinical course of breast carcinoma. Clinical course is governed by two components: likelihood of cure and median tumor‐related survival time among uncured patients. Estimates of these components can be derived only by using survival models that incorporate cured fraction as a specific parameter.

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Ian W. McLean

Armed Forces Institute of Pathology

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Jerry A. Shields

Thomas Jefferson University

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Daniel M. Albert

University of Wisconsin-Madison

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