TTT boosts radiotherapy for choroidal melanoma

By Sean Henahan

PHILADELPHIA — Adjunctive transpupillary thermotherapy (TTT) following plaque radiotherapy for choroidal melanoma provides good tumour control over time with a very low rate of recurrence, report researchers from the Wills Eye Hospital, Philadelphia, US.
Carol L. Shields MD and colleagues prospectively studied the effects of combined plaque radiotherapy and transpupillary thermotherapy in 270 consecutive patients with new diagnoses of melanoma.

Following radiotherapy, all patients received three treatments with transpupillary thermotherapy using an infrared laser.

The first TTT treatment occurred in the operating room immediately following plaque removal and the remainder at four-month intervals in the office setting.
After one year, tumours decreased from a the median thickness of 4.0 mm to a median of 2.3 mm. This declined to a median thickness of 2.1 mm after two years, remaining stable in most cases thereafter.

The tumour recurrence rate was 2% at two years and 3% after five years. Statistically significant factors associated with recurrence included macular location, margin underneath the fovea and diffuse tumour configuration.
The recurrences involved only five of the original group of 270 patients. All the local recurrences were on the posterior margin.

The team detected the recurrences at a mean time of 21 months following initial treatment, within a range of eight to 27 months.
One case was considered a suitable candidate for additional thermotherapy, while the other four required enucleation.


According to Dr Shields, these results compare favourably with other treatment approaches. Previous published reports show a five-year relapse rate of 12% with 60Co plaque radiotherapy, 11% with 106Ru plaque radiotherapy, and 5% with proton beam radiotherapy.

The 125I plaque radiotherapy used by Dr Shield’s group has a reported five-year recurrence rate of 4%. They now also prefer to use adjunctive TTT to further improve local tumour control.

Prior to receiving treatment, 76% of eyes had visual acuity between 20/20 to 20/50; 13% between 20/60 to 20/100; and 10% with 20/200 or worse.
At the last follow-up visit, only 37% of eyes were 20/50 or better, with 16% between 20/60 and 20/100 and 46% at 20/200 or worse. This is similar to what has been reported in other series of patients undergoing plaque radiotherapy.

Both plaque radiotherapy and TTT can produce complications. In this series, complications seen at five years included papillopathy in 38% of patients; maculopathy in 18%; macular retinal vascular obstruction in 18%; and vitreous haemorrhage in 18% of cases.

Less common treatment-related problems included neovascular glaucoma in 7% of patients, cataract in 6% and rhegmatogenous retinal detachment in 2%. Complications associated with radiotherapy accounted for three cases of enucleation.

The publication of the Collaborative Ocular Melanoma Study (COMS) (Archives of Ophthalmology; July 2001) provided considerable support for the use of conservative, sight sparing treatments instead of enucleation.

The five-year COMS protocol showed comparable survival rates among the 8,712 patients with choroidal melanoma randomised to iodine 125 brachytherapy or enucleation.

The results of the current study suggest the possibility of added benefit with the use of adjunctive TTT. This is based on the idea that reducing local tumour recurrence improves overall survival results. The 97% local tumour control seen in this study is the best reported to date.

Dr Shields also credited enhancements in plaque radiotherapy with the improved outlook for ocular melanoma patients. Recent developments in plaque design allow a more customised approach to treatment.

Oncologists now typically use an array of 125I seeds tailored to each patient rather than the one-size-fits all approach of the past. In particular, it is now easier to reach tumours in difficult locations like those overhanging the optic disc.

The place for TTT in the treatment of ocular melanoma is still being determined. It will most likely be reserved as an adjunctive therapy for smaller tumours that can be reached most easily by the transpupillary route.

The timing of TTT also requires additional study with some surgeons applying the laser immediately after radiotherapy, while others prefer to wait or reserve it for cases of tumour non-response or recurrence.

The study appears in Archives of Ophthalmology 2002; 120: 933-940.

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