Episcleral plaque radiotherapy in the treatment of uveal melanomas

Radiobiological doses, tumor, and treatment features influence on local control, enucleation rates, and survival after epiescleral brachytherapy. A 20-year retrospective analysis from a single-institution: part I

PURPOSE

To assess influence of the radiobiological doses, tumor, and treatment features on local control, enucleation rates, overall and disease-specific survival rates after brachytherapy for posterior uveal melanoma.

MATERIAL AND METHODS

Local control, enucleation, overall and disease-specific survival rates were evaluated on the base of 243 patients from 1996 through 2016, using plaques loaded with iodine sources. Clinical and radiotherapy data were extracted from a dedicated prospective database. Biologically effective dose (BED) was included in survival analysis using Kaplan-Meier and Cox regressions. The 3-, 5-, 10-, and 15-year relative survival rates were estimated, and univariate/multivariate regression models were constructed for predictive factors of each item. Hazard ratio (HR) and confidence interval at 95% (CI) were determined.

RESULTS

The median follow-up was 73.9 months (range, 3-202 months). Cumulative probabilities of survival by Kaplan-Meier analysis at 3, 5, 10 and 15 years were respectively: 96%, 94%, 93%, and 87%, for local control; 93%, 88%, 81%, and 73% for globe preservation; 98%, 93%, 84%, and 73% for overall survival, and 98%, 96%, 92%, and 87% for disease-specific survival. By multivariate analysis, we concluded variables as significant: for local control failure - the longest basal diameter and the juxtapapillary location; for globe preservation failure - the longest basal dimension, the mushroom shape, the location in ciliary body, and the dose to the foveola; for disease-specific survival - the longest basal dimension. Some radiobiological doses were significant in univariate models but not in multivariate ones for the items studied.

CONCLUSIONS

The results show as predictive factors of local control, enucleation, and disease-specific survival rates those related with the features of the tumor, specifically the longest basal dimension. There is no clear relation between radiobiological doses or treatment parameters in patients after brachytherapy.

Clinical Application of Proton Beams in the Treatment of Uveal Melanoma: The First Therapies Carried Out in Italy and Preliminary Results (Catana Project)

Background

The first Italian proton therapy facility was realized in Catania, at the INFN-LNS. With its energy (62 MeV proton beam), it is ideal for the treatment of shallow tumors like those of the ocular region: uveal melanoma, first of all (the most common primary intraocular malignancy of adults) and other less frequent lesions like choroidal hemangioma, conjunctiva melanoma, and eyelid tumors.

Material and methods

The first patient was enrolled in February 2002, and to date 30 patients have been treated. All patients had a localized uveal melanoma, with no systemic metastases, and had specific indications for proton beam radiation therapy: lesions between 5–25 mm basal diameter, not exceeding 15 mm thickness, absence of total retinal detachment or glaucoma. According to the tumor dimensions, 2 patients had a small lesion or T1 (6%), 3 had a medium-sized lesion or T2 (10%), 14 had a large lesion or T3 (47%), and 11 had an extra-large lesion or T3 (37%); no patient had extrascleral invasion or T4 of the TNM-AJCC Staging System. In most cases, the tumor infiltrated only the choroid (14 patients, 47%) or the choroid plus the ciliary body (14 patients, 47%). We also treated a primitive iris melanoma, without diffusion to the ciliary body. The target volume was defined as the tumor plus a safety margin of 2.5 mm, laterally and antero-posteriorly; this margin was increased to 3 mm if ciliary body involvement was present. The treatment was carried out in 4 fractions on 4 consecutive days to a total dose of 54.5 Gy (single fraction 13.6 Gy), which corresponds to 60 CGE (Cobalt Gray Equivalent; single fraction 15 CGE), because the relative biological effectiveness is 1.1.

Results

The first follow-up is planned at 6–8 months after the end of the treatment, and our clinical end points are local control (defined as cessation of growth or tumor shrinkage), eye retention, and maintenance of a good visual function. At the time of this writing, we had preliminary results from 13 patients. Nine patients showed tumor shrinkage (69%), 3 a substantially stable dimension (23%), but almost all patients presented an increased ultrasound reflectivity (a surrogate for tumor control).

Discussion and conclusions

The literature data show that charged particle therapy has allowed an optimal local control in the treatment of uveal melanomas (about 96% in the different series, superior to that obtained with plaquetherapy [between 83% and 92%]), a metastatic rate slightly better than enucleation reports, and a survival rate of almost 90% at 5 years. Our preliminary results show a tumor response in almost all cases, with no major acute or subacute side effects. We thus plan to continue with our treatment procedures and our dose prescription.

Secondary Enucleations for Uveal Melanoma: A 7-Year Retrospective Analysis

PURPOSE

To describe the indications for secondary enucleations in uveal melanoma and analyze associations and outcomes.

DESIGN

Retrospective interventional case series.

METHODS

Data of patients who underwent secondary enucleation for uveal melanoma in the London Ocular Oncology Service, between 2008 and 2014, were retrieved from medical records analyzed. Cox regression model was performed to analyze associations with secondary enucleation and metastases and Kaplan-Meier estimates to assess the probability of metastatic spread and death.

RESULTS

During the study period 515 enucleations were performed for uveal melanoma, 99 (19%) of which were secondary enucleations. Tumors were located at the ciliary body in 21 eyes (21%), juxtapapillary in 31 (31%), and choroid elsewhere in 47 (48%). Primary treatment included Ru(106) plaque radiotherapy, proton beam radiotherapy, and transpupillary thermotherapy in 85, 11, and 3 eyes, respectively. Indications for secondary enucleation were tumor recurrence in 60 (61%), neovascular glaucoma in 21 (21%), and tumor nonresponse in 18 eyes (18%). Twenty patients (20%) were diagnosed with metastasis and 12 out of 20 died of metastatic spread. On multivariate analysis, juxtapapillary tumor location was found to associate with tumor nonresponse (P = .004) and nonresponding patients with metastatic spread (P = .04).

CONCLUSIONS

Indications for secondary enucleations for uveal melanoma were tumor recurrence, neovascular glaucoma, and tumor nonresponse. This review identified a possible high-risk group (nonresponse), which proved radioresistant to treatment. These tumors were more frequently found in the juxtapapillary location and were associated with metastatic spread.

Episcleral plaque 125I radiotherapy with episcleral LCF hyperthermia: a prospective randomized trial

PURPOSE

The purpose of this study was to search for an optimal radiation dose in the treatment of patients with uveal melanoma using 125I episcleral plaque radiotherapy (EPRT) and episcleral hyperthermia (HT).

METHODS AND MATERIALS

From 1991-1998, 35 patients with uveal melanoma were enrolled in a phase II prospective randomized trial of 125I EPRT combined with episcleral HT. Two groups were closely matched for pre-treatment patient and tumor characteristics. Group 1: N = 16, and Group 2: N = 19. The median dose to the tumor apex for Group 1 was 80.0 Gy and 60.8 Gy for Group 2. Episcleral HT was given once for 45 min immediately prior to EPRT with a median temperature of 44 degrees C for both groups. The median follow-up was 5.5 years for Group 1 and 5.3 years for Group 2.

RESULTS

The median tumor height decreased 1.7 mm for patients of both groups. The 5- and 8-year probability of local recurrence was 33% for Group 1, and 25% for Group 2, p = 0.73. The 5-year probability of DFS was 54% for Group 1 and 67% for Group 2, p = 0.51. The 5- and 8-year overall survival was 68% and 34%, respectively, for Group 1, and 83% and 50%, respectively, for Group 2, p = 0.60. The rate of distant metastasis at 5- and 8-years for Group 1 was 29% and 62%, respectively, and 17% and 17%, respectively, for Group 2, p = 0.18. The incidence of enucleation was 4 (25%) in Group 1 vs. 4 (22%) in Group 2. The incidence of late complications was similar in either treatment group. The ambulatory visual acuity (> 5/200) at last follow-up was slightly better in Group 2 (80%) than Group 1 (64%).

CONCLUSIONS

Treatment outcomes were similar despite a 25% difference in radiation dose. In view of these findings and in an attempt to reduce the incidence of late treatment toxicity a still lower radiation dose in combination with HT needs to be studied. The reported outcomes need to be evaluated with caution due to the small number of patients in this study.

A reanalysis of the Collaborative Ocular Melanoma Study Medium Tumor Trial eye plaque dosimetry

PURPOSE

To recalculate the radiation doses delivered to structures of interest within the eye, i.e., the lens, tumor apex, 5-mm point, optic disk, and macula for patients treated with eye plaque radiotherapy on the Collaborative Ocular Melanoma Study (COMS) Medium Tumor Trial, using updated dosimetric data.

METHODS AND MATERIALS

Using the Plaque Simulator planning system, doses were recalculated for a sampling of COMS patients for each plaque size. Dosimetry parameters incorporated into the recalculation were line source approximation, a 90% Silastic transmission factor, and a 0% gold transmission factor. Generic solutions were generated from the dose recalculations for each plaque size and structures of interest combination. Doses for the remainder of the patient population were recalculated using the generic solutions and compared with the originally reported COMS doses.

RESULTS

Doses to all structures of interest were reduced 7%-21%, depending on the plaque size and structure combination. The reduction in dose for the macula, optic disc, lens, tumor apex, and 5-mm point was on average 10%, 18%, 8%, 11%, and 12%, respectively. The closer the macula and optic disk were to the plaque rim, the greater the dose reduction. Incorporation of the Silastic transmission factor accounted for a large part of the dose reduction.

CONCLUSIONS

Incorporating anisotropy, line source approximation, and Silastic and gold shield attenuation into dose recalculations resulted in a significant and consistent reduction of doses to structures of interest within the eyes.

Eye retention after proton beam radiotherapy for uveal melanoma

PURPOSE

To analyze the long-term results of eye retention after conservative treatment of uveal melanoma with proton beam radiotherapy, and to analyze the causes leading to enucleation after this conservative treatment approach.

MATERIALS AND METHODS

This was a prospective, noncomparative, interventional, consecutive case series. A total of 2645 patients (2648 eyes) with uveal melanoma were treated between 1984 and 1999 with proton beam radiotherapy. Data were analyzed as of February 2001. Patients' age ranged from 9 to 90 years, 1284 were men, and 1361 were women. Largest tumor diameter ranged from 4 to 27.5 mm, and tumor height from 0.9 to 15.6 mm. Median follow-up time was 44 months.

RESULTS

The overall eye retention rate at 5, 10, and 15 years after treatment was 88.9%, 86.2%, and 83.7%, respectively. In total, 218 eyes had to be enucleated. Enucleation was related to larger tumor size, mainly tumor height, proximity of posterior tumor margin to optic disc, male gender, high intraocular pressure, and large degree of retinal detachment at treatment time. After optimization of the treatment technique, the eye retention rate at 5 years was increased from 97.1% to 100% for small tumors, from 86.7% to 99.7% for medium, and from 71.1% to 89.5% for large tumors.

CONCLUSIONS

The treatment technique as used today results in excellent eye retention rates, even in less favorable cases such as large tumors and tumors located close to the optic disc. The experience and a continuous quality control program allowed us to improve the 5-year eye retention rate for all tumor sizes. These findings demonstrate the positive impact of experience and quality control-based efforts for treatment technique optimization.

Leksell gamma knife treatment of uveal melanoma

Object. The purpose of this study was to analyze treatment results, radiation-induced side effects, and prognostic survival factors for patients with uveal melanoma.

Methods. Eighty-one patients with uveal melanoma were treated using the Leksell gamma knife during a period of 6 years (1996–2001). There were 45 men and 36 women with a median age of 59 years (range 22–85 years). Seventyfive of these patients underwent minimal follow up 10 months after treatment. After patient eye immobilization, magnetic resonance (MR) imaging was performed to enable stereotactic localization. A scoring system was used to measure radiation side effects. The median target volume was 640 mm3, and the median applied minimal dose was 31.4 Gy. All patients were examined by an ophthalmologist and with MR imaging at regular intervals. Factors influencing posttreatment survival and side effects were statistically analyzed.

Conclusions. Local tumor control in the 75 patients who underwent minimal follow up after 10 months was achieved in 63 patients (84%), whereas progression was observed in 12 patients (16%). The most frequent side effect was secondary glaucoma, which was detected in 18 patients (25%). The incidence of this side effect was significantly higher when the total volume of peripheral isodose was greater than 1000 mm3 (p = 0.015). Toxicity in the optic nerve here was also significantly higher when the maximum dose to this structure was higher than 9 Gy (p = 0.011), in the cornea when the maximum dose was higher than 15 Gy (p = 0.010), and in the lens when the maximum dose was higher than 10 Gy (p = 0.035). Altogether three pretreatment variables (patient age, tumor location, and dissemination of the disease) and one treatment variable (the minimum dose applied) were identified as having a significant influence on a patient's survival.

Maximizing local tumor control and survival after proton beam radiotherapy of uveal melanoma

PURPOSE

This study reports local tumor control and survival after proton beam radiotherapy (PBRT) of uveal melanoma. It identifies the risk factors for local tumor-control failure and for ocular tumor-related death. It presents the improvements implemented to increase the rate of local tumor control, and compares the survival rate of patients with locally controlled tumors to those of patients who had to receive a second treatment.

PATIENTS AND METHODS

We have treated 2,435 uveal melanomas with PBRT between March 1984 and December 1998. Data were analyzed as of September 1999. Patients' age ranged from 9 to 89 years; there were 1,188 men and 1,247 women. The largest tumor diameter ranged from 4 to 26 mm, and tumor thickness from 0.9 to 15.6 mm. Median follow-up time was 40 months.

RESULTS

Local tumor control probability at 5 years was improved from 90.6 +/- 1.7% for patients treated before 1988, to 96.3 +/- 0.6% for patients treated between 1989 and 1993, and became 98.9 +/- 0.6% for patients treated after 1993. Among 2,435 treated patients, 73 (3%) had to receive a second treatment because of tumor regrowth. Cause-specific survival at 10 years was calculated to 72.6 +/- 1.9% for patients with controlled tumors compared to 47.5 +/- 6.5% for those with recurrent tumors.

CONCLUSION

Reduced safety margins, large ciliary body tumors, eyelids within the treatment field, inadequate positioning of tantalum clips, and male gender were identified to be the main factors impairing local tumor control. The improvement of local tumor control rate after 1993 is attributed to changes implemented in the treatment procedure. Our data strongly support that the rate of death by metastases is influenced by local tumor control failure: improvement of the local tumor control rate results in a better survival rate.

Preliminary experience in the treatment of choroidal melanoma with gamma knife radiosurgery

Object. The authors report their early results from an ongoing experience treating patients with choroidal melanoma by using gamma knife radiosurgery (GKS).

Methods. Between September 1998 and March 2000, 11 patients were treated for choroidal melanoma. Treatment was facilitated with specialized frame placement. Eye immobilization was accomplished with supra- and infraorbital nerve block and tethering sutures to the periorbital tissue. Magnetic resonance imaging was performed to localize the tumor for treatment planning. Plugging patterns were used to steer fall-off radiation away from the fovea, optic nerve, or lens. Tumor volume, tumor location relative to critical structures, and dose to critical structures were determined using GammaPlan. Tumor response was determined using ultrasonography. Toxicity was determined by clinical assessment, visual acuity testing, and ophthalmoscopy.

All 11 patients successfully completed the treatment. In every case, 40 Gy was prescribed to the 50% isodose, which completely encompassed all visible tumor. Tumor height ranged from 2.9 to 7 mm. The tumor diameter ranged from 6 to 13 mm. The range of follow up was 2 to 19 months. No tumor has progressed. One patient had improvement in vision because of improvement in retinal detachment. Two patients experienced visual decline. One patient's visual decline was due to a vitreous hemorrhage, and the other's was due to hard exudates encroaching on the macula. One patient has developed a dry eye that is managed effectively with topical eye lubricants.

Conclusions. This preliminary experience demonstrates that GKS is a feasible treatment option for small- to medium-sized choroidal melanomas. Longer follow up and additional patients will be required to improve the assessment and the ultimate tumor control and toxicity in this ongoing series.

Radioactive plaque therapy for metastatic choroidal carcinoma

PURPOSE

To describe the outcome of radioactive episcleral plaque therapy for treatment of metastatic carcinoma to the choroid.

DESIGN

Retrospective, noncomparative case series.

PARTICIPANTS

Five patients (six eyes) with carcinoma metastatic to the choroid.

METHODS

Retrospective review of the clinical records of five patients (six eyes) who underwent radioactive episcleral plaque therapy for choroidal metastases.

MAIN OUTCOME MEASURES

Tumor height, visual acuity, radiation optic neuropathy, and radiation retinopathy.

RESULTS

Radioactive episcleral plaque therapy resulted in shrinkage of the treated tumors and resolution of subretinal fluid in all eyes. After plaque treatment, best-corrected visual acuity was maintained within two lines of initial visual acuity for two eyes, decreased more than two lines for one eye, and improved more than two lines in three eyes. The treatment was well tolerated and there was no acute toxicity. Late complications included optic nerve atrophy (at 2 years) with proliferative radiation retinopathy (at 3 years) in one eye and optic atrophy (at 6 months) in another eye that had received prior external beam therapy.

CONCLUSIONS

In carefully selected cases, radioactive episcleral plaque therapy appears to be an effective and reasonable treatment for carcinoma metastatic to the choroid.

Stereotactic radiation therapy for malignant choroidal tumors: preliminary, short-term results

PURPOSE

To evaluate the role of stereotactic radiation therapy (SRT) in the treatment of malignant choroidal tumors.

DESIGN

Prospective, noncomparative case series.

PARTICIPANTS

Ten patients with unifocal choroidal metastasis (three lung carcinoma, three breast carcinoma, three colon carcinoma, one cutaneous melanoma) and five patients with primary choroidal melanoma underwent single-dose or fractionated SRT.

METHODS

Before treatment, computed tomography (CT) scans of the orbit were obtained with the patient wearing an individualized immobilization mask. An integrated macro-CCD-camera system viewed the eye for detection of movements. Three-dimensional computer-based treatment planning was carried out. Dose distribution was calculated and displayed in isodose lines on the CT data set. For SRT, a dedicated stereotactic linear accelerator (6 MV) was used. Total doses for choroidal metastases were 12 to 20 Gy in a single dose or 30 Gy over 10 days (3 Gy each session), and total doses for choroidal melanoma were 50 Gy over 5 or 10 days (10 or 5 Gy each session).

MAIN OUTCOME MEASURES

Best corrected visual acuity (ETDRS-chart), biomicroscopy, ultrasound examination, fluorescein angiography, and magnetic resonance imaging (MRI) were performed before treatment and at regular intervals after completion of SRT.

RESULTS

During a follow-up period from 1 to 34 months (median, 6.5 months), local tumor control was achieved in all eyes. A decrease in tumor size on ultrasonography or MRI was noted in eight patients. No persistent side effects were observed during follow-up.

CONCLUSIONS

Stereotactic radiation therapy allows steep dose gradients outside the target volume by minimizing the field of exposure. Thus only low radiation doses affect surrounding radiosensitive ocular structures. Our initial findings suggest that this technique may be effective in controlling tumor growth. Further studies are needed to compare treatment efficacy and safety with conventional treatment methods.

Internal resection of posterior uveal melanomas

AIMS

To evaluate the safety and efficacy of internal resection in the treatment of malignant melanoma of the choroid.

METHODS

32 consecutive patients with histopathologically proved malignant choroidal melanomas were treated with internal resection. 29 of the 32 (90.6%) tumours were within 2 disc diameters of the optic nerve or fovea. The surgery was performed at two university centres by one of the authors. Follow up was between 1 and 85 months (mean 40.1 months).

RESULTS

Three patients developed distant metastases and died of malignant melanoma (metastatic and mortality rate 9.4%). In one case, distant metastases developed in association with an intraocular recurrence. There have been no other intraocular recurrences. The most common postoperative complication was vitreous haemorrhage, which occurred in 12 patients (37.5%); cataract occurred in eight eyes; and three patients developed retinal detachment postoperatively. Three of the operated eyes have been enucleated (9.4%); a total of four (12.5%) have lost light perception. 10 patients (31.2%) had visual acuities of 6/60 or better and 18 of 32 (56.3%) were between 6/120 and light perception.

CONCLUSION

These data suggest that the internal resection of posterior uveal melanomas is a reasonable globe saving management option. This treatment modality is particularly well suited to elevated tumours in close proximity to the optic nerve or fovea.

Conformal episcleral plaque therapy

PURPOSE

Episcleral plaque therapy (EPT) with sealed 125I sources is widely used in the treatment of choroidal melanoma. In EPT, as elsewhere in radiotherapy, concern for normal tissue tolerance has frequently been a dose-limiting factor. The concept of conformal therapy, which seeks to improve dose homogeneity within the tumor and greatly reduce the dose to uninvolved structures may provide a solution to this problem. Radioactive sources are typically distributed uniformly over the surface of an episcleral plaque and are sometimes offset slightly from the scleral surface to reduce the dose to the sclera relative to the apex and prescribed therapeutic margin at the tumor base. Nevertheless, it is not uncommon for scleral dose to exceed the dose to the apex of intermediate to tall tumors by a factor of 4 or more. The availability of low-energy sealed sources such as 125I prompted the development of gold-backed plaques to shield noninvolved periocular tissues. The concept of shielding can be extended to include collimation of individual sources. The potential advantages of individual source collimation include reduced scleral dose, more homogeneous tumor dose, and superior shielding of adjacent normal structures such as the fovea as compared to previous plaque designs.

METHODS AND MATERIALS

A three-dimensional treatment-planning system has been extended to design a plaque that incorporates individually collimated 125I sources. Thermoluminescent dosimetry (TLD) and radiochromic film were used to compare calculated dose-rate distributions with measured dose rates in an acrylic phantom.

RESULTS

Calculations predict that source collimation in the form of a "slotted" gold plaque will achieve the purposes of the study. The collimating effect of the slots is demonstrated qualitatively using radiochromic film, and the accuracy of the calculation is demonstrated quantitatively with TLD.

CONCLUSION

The episcleral plaque described in this report is simpler to assemble than previous plaque designs. It produces a more homogeneous dose distribution in the tumor, reduces scleral dose by up to 50% as compared to conventional designs, and significantly reduces radiation dose to uninvolved structures adjacent to the plaque.

Radiation therapy for malignant melanoma

Sufficient biologic and clinical evidence now exists to refute the longstanding dogma that melanomas are uniformly radiation resistant and hence radiation therapy has little role in the management of this disease. Although surgery remains the treatment of choice for the vast majority of localized melanomas, available data indicate that radiation therapy is a viable alternative for a few subsets of patients in whom surgery would result in cosmetic or functional deformity, such as patients with large facial lentigo maligna melanomas or small or intermediate-sized uveal melanomas. Retrospective and Phase II prospective studies have revealed that elective/adjunctive radiation therapy improves the local-regional control rate in patients with thick primary lesions, nodal involvement, or mucosal melanomas. However, the impact of elective/adjunctive radiation therapy on the survival rate has yet to be determined. Radiation therapy has been established as a simple and cost-effective treatment modality for palliation of patients with symptomatic metastatic spread. The response of metastatic deposits to radiation varies with the tumor volume, total dose, and dose per fraction. The choice of optimal fractionation depends on tumor site and the patient's survival expectation. New data indicate that hyperthermia enhances the response of metastatic lesions to radiation. Ongoing research with a variety of experimental strategies may offer the possibility of further increasing the utility of radiation therapy in the management of this disease.

125I plaque therapy for uveal melanoma. Analysis of the impact of time and dose factors on local control

BACKGROUND

125I episcleral plaque therapy has gained wide acceptance for the treatment of uveal melanoma because of its potential to preserve vision, salvage the globe, and provide good local control. A rigorous analysis of the optimum radiation dose, dose rate, and overall treatment time has not been reported with this technique.

METHODS

One hundred fifty patients with uveal melanoma treated with 125I plaques between 1982 and 1990 and included in the uveal melanoma study (UMS) database of the Wills Eye Hospital were analyzed. Mean patient age was 60.7 years (range: 17.7-84.6 years). Initial mean tumor size was 9.7 x 8.5 x 3.7 mm with a range of 4.5 to 21.5 mm in basal dimension and 1.2 to 11.8 mm in height. Mean dose to the tumor apex was 94.77 gray (Gy) (29.5-141 Gy). Mean dose rate to the tumor apex was 92.9 cGy/hr (10-292 cGy/hr); the mean dose to the base was 359 Gy (181-692 Gy); the mean dose rate to the base was 348 cGy/hr (112-893 cGy/hr); and mean duration of treatment was 124.7 hours (range: 28-333 hours)

RESULTS

With a median follow-up of 68 months, there have been 33 local failures. Mean time to local failure was 19 months (range: 6-78 months). Actuarial local control is 81% at 5 years. Multivariate analysis demonstrates significant correlation of local failure with larger tumor dimension (P = 0.0046), close proximity to the optic disc (P = 0.0029), lower radiation dose to the tumor apex (P = 0.03), lower radiation dose rate to the tumor apex and base (P = 0.01 and 0.03), and longer overall treatment time (P = < 0.0001).

CONCLUSIONS

This retrospective analysis reinforces the importance of dose rate, minimum tumor dose, overall treatment time, maximum tumor basal dimension, and proximity to the optic nerve in the treatment of uveal melanoma.

Episcleral plaque thermoradiotherapy of posterior uveal melanomas

Episcleral plaque radiotherapy is a widely applied treatment for selected patients with uveal melanomas. This treatment is well tolerated but may produce severe late radiation complications resulting in decreased visual acuity that reduces the attractiveness of conservative therapy. The purpose of this study was to access if the addition of episcleral hyperthermia decreases late radiation complications through radiation dose reduction while maintaining high incidence of local tumor control. In a 3-year period, episcleral plaque thermoradiotherapy was given to 25 patients with uveal melanoma in a Phase I study. The mean tumor height was 6.2 mm and the mean tumor basal area was 173 mm(2). The mean radiation dose given to the tumor apex was 72.2 Gy and the mean hyperthermia temperature, given once for 45 min, was 43.5 degrees C. Of the 25 patients treated, 22 (88%) showed tumor height reduction, 2 (8%) showed no change, and 1 (4%) had an increase in tumor height. At the last follow-up (range, 20-68 months; mean, 31.2 months), a 43% mean tumor height reduction was recorded (p = 0.0002). Of the 22 patients initially showing tumor regression, 2 (9%) had subsequent tumor progression. At least ambulatory vision (>5/200) was maintained by 20 (80%) patients. Severe complications, including hemorrhagic retinal detachment and a large vitreous hemorrhage, were seen in 2 (8%) patients early in this Phase I study. The treatment program was well tolerated by the study patients. Severe late treatment toxicity was sharply reduced by limiting the mean scleral temperature to < or equal to 44 degrees C. This study employing 30% lower radiation doses, showed tumor regression in the majority of patients. Longer follow-up is needed to assess long-term treatment efficacy and late treatment complications.