Plaque radiotherapy effective for conjunctival squamous cell CA invading the sclera

By Will Boggs MD

NEW YORK (Reuters Health) - Plaque radiotherapy is effective for conjunctival squamous cell carcinoma (SCC) in patients who have scleral or anterior chamber invasion following wide initial surgery, according to a retrospective series.

Management of conjunctival SCC usually involves excisional biopsy, alcohol-treated limited superficial keratectomy, and conjunctival cryotherapy. Secondary therapy can include topical medications, but these are not effective when the tumor invades the sclera or the globe.

Dr. Carol L. Shields from Thomas Jefferson University, Philadelphia, Pennsylvania and colleagues report the results of 15 patients with conjunctival SCC who had scleral or anterior chamber invasion after conventional management and were treated with plaque radiotherapy.

Plaque radiotherapy was applied for 93 to 170 hours (median, 142 hours), with a mean base dose of 45 to 285 Gy (median, 67 Gy), according to the February 20th JAMA Ophthalmology online report.

Radiation complications included cataract in 13 eyes, iris telangiectasia in five, corneal epithelial defect in four, corneal edema in three, and glaucoma in one.

Visual acuity remained stable after treatment in four eyes, but decreased in 11 eyes as a result of cataract or glaucoma.

Local tumor control was achieved in all 15 cases at mean follow-up of 42 months (range, seven to 96 months), but tumor recurrence remote from the radiotherapy site (but within the globe) occurred in four cases at one to eight months' follow-up (median, five months).

Treatment for remote recurrence included orbital exenteration in two eyes and enucleation in two eyes.

Overall, globe salvage was achieved in 10 cases (67%).

"Plaque radiotherapy provides precise, targeted therapy to affected structures with decreasing dose to immediately surrounding tissues and relatively low dose to more remote normal tissue," the researchers explain.

"Plaque radiotherapy is a safe and reliable alternative to globe removal for eyes with conjunctival SCC demonstrating scleral invasion and/or intraocular involvement," the authors conclude. "Precise radiotherapy isodose design and plaque placement are critical in aligning the focal radiation field appropriately."

"Affected eyes should be followed up for remote recurrence at other sites," they add.

Dr. Paul T. Finger from The New York Eye Cancer Center, New York has published extensively on the use of plaque radiotherapy. He told Reuters Health, "Plaque therapy can be used as an investigational therapy to salvage eyes with invasive conjunctival SCC."

"There are many alternatives to enucleation for most conjunctival SCC patients," Dr. Finger explained. "However, radiation is only being considered for the invasive form. Once the tumor has invaded, topical chemotherapy or even standard cryotherapy are less likely to cure. However, all chemo and all methods of cryotherapy are not equal nor widely available."

"Care must be taken to define the edges of the invasive conjunctival SCC," Dr. Finger said. "Diagnostic techniques should include high frequency ultrasound imaging (also called UBM) to evaluate the sclera and subjacent uvea for invasion as well as tumor width. At our center, we only use plaque therapy for patients with conjunctival SCC that involves the uvea (iris, ciliary body, or choroid). Once the tumor is in the eye, the patient should be counseled that they might risk secondary (post-plaque) enucleation or exenteration. All of these patients should be evaluated for metastases."

"These cases should be carefully selected for plaque treatment by experienced eye cancer specialists," Dr. Finger concluded.

Dr. Shields did not respond to a request for comments.

SOURCE: http://bit.ly/1kiTfSM

JAMA Ophthalmol 2014.

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