title: Prescribing to tumor apex in episcleral plaque iodine-125 brachytherapy for medium-sized choroidal melanoma: A single-institutional retrospective review.
abstract: OBJECTIVE
  To report an institutional experience with episcleral plaque brachytherapy for medium-sized uveal melanoma. Variations in prescription dose point and dose rate were compared with Collaborative Ocular Melanoma Study (COMS) Group.
  
  
  METHODS
  A retrospective review was performed for 116 patients treated with iodine-125 plaque brachytherapy. About 85 Gy was prescribed to either the tumor apex (108 patients) or at 5 mm (8 patients) with dose rate ranging from 50.6 to 98.2 cGy/h. Patients were followed up for local tumor control, eye preservation, and vision retention. Dose and dose rate to tumor and sensitive structures were calculated. Multivariate and univariate analyses were performed to investigate correlation between clinical outcomes and dose/dose rate variables.
  
  
  RESULTS
  Patients in this study were slightly older with worse visual acuity at baseline, but tumor size and position and ratio of ciliary body involvement were comparable to COMS population. Outcomes data were comparable to COMS: 95.3% local tumor control at 5 years and 77.7% vision preservation at 3 years. Only 4 patients needed enucleation because of tumor growth. Significant correlation was found between enucleation and tumor height and maximal scleral dose/dose rate as well as vision retention and tumor height and macula dose/dose rate.
  
  
  CONCLUSIONS
  For tumors with <5 mm height, prescribing to tumor apex enabled to decrease dose to all sensitive structures without any loss of local control. Although dose rate was lowered to 50.6 cGy/h from the American Brachytherapy Society guidelines (60-105 cGy/h) because of limited availability of operating room (i.e., weekly), there was no difference in either local tumor control or complications.
authors.affiliation: Arizona Oncology, Tucson, AZ.
authors.forename: David Thomas
authors.initials: DT
authors.lastname: Vonk
authors.affiliation: Department of Radiation Oncology, University of Arizona, Tucson, AZ.
authors.forename: Yongbok
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Department of Ophthalmology, University of Arizona, Tucson, AZ; Retina Associates, Tucson, AZ.
authors.forename: Cameron
authors.initials: C
authors.lastname: Javid
authors.affiliation: Department of Radiation Oncology, InterMountain Health Care, Murray, UT.
authors.forename: John D
authors.initials: JD
authors.lastname: Gordon
authors.affiliation: Department of Radiation Oncology, University of Arizona, Tucson, AZ. Electronic address: bstea@email.arizona.edu.
authors.forename: Baldassarre
authors.initials: B
authors.lastname: Stea
mesh_terms: D000368:Aged; D001918:Brachytherapy / Q000379:methods*; D002830:Choroid Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D002924:Ciliary Body; D015353:Eye Enucleation; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008266:Macula Lutea / Q000528:radiation effects; D008297:Male; D008545:Melanoma / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D008875:Middle Aged; D059351:Organ Sparing Treatments; D011829:Radiation Dosage; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D012590:Sclera / Q000528:radiation effects; D016896:Treatment Outcome; D047368:Tumor Burden; D014792:Visual Acuity
chemical_list: D007457:Iodine Radioisotopes
keywords: (125)I; Dose rate; Episcleral plaque; Uveal melanoma