Choroidal Melanoma: Treatment of Metastatic Disease

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Choroidal Melanoma: Treatment of Metastatic Disease

Disease Entity [1]

Choroidal Melanoma is the most common primary intraocular malignant tumor and the second most common intraocular tumor, behind metastases. It is estimated that up to 50% of patients with choroidal melanoma develop metastatic disease, despite successful treatment of the primary tumor. There is debate on whether or not metastatic spread is preventable, due to the belief that it has already occurred by the time an ocular tumor is detected. 

Management[1][2]

There are several methods of treatment for Choroidal Melanoma, however there is no known effective adjuvant systemic therapy to reduce the risk of metastasis. The presence of metastatic disease on initial diagnosis drastically alters treatment and prognosis. Counseling patients on treatment is difficult, as interventions likely lead to loss of vision or the eye itself. 

Surveillance[3]

The development of metastatic disease arising from choroidal melanoma is associated with a worse prognosis. One first step in management is to monitor as assess for metastases directly following a primary melanoma diagnosis. This is beneficial in high risk patients, which can be classified according to an individual's tumor size, genetic profile, and tumor location. Gene expression profile testing is one method to evaluate risk. Though there is no proven survival benefit with early detection of metastases, it can allow for diagnosis of metastases that are treatable with surgery or targeted, local therapies. 

General Treatment[1][2]

Enucleation has long been considered the mainstay of treatment for medium and large choroidal melanoma. However, there are other vision-sparing approaches that offer similar degrees of metastatic and ocular tumor control, such as radiotherapy and surgical resection of the focal tumor. Brachytherapy is often the first choice of treatment in most medical centers. Exoresection involves surgical excision of the tumor through a large scleral opening, another eye-sparing approach. At the time of diagnosis, it is common that the tumor has already undergone micrometastasis to local sites, reducing the effectiveness of enucleation. Some clinicians argue for a dual resection and radiotherapy approach. 

Medical Therapy[1][2]

Systemic chemotherapy, such as dacarbazine, is suggested as the primary treatment when distant metastases are found on initial evaluation. Treatment of ocular melanoma is palliative in this case. While checkpoint inhibitors are effective in targeting metastatic cutaneous melanoma, they have not been shown to be successful in treating intraocular melanoma. 

Prognosis[1]

Though current evidence is inadequate in predicting an accurate prognosis for patients with choroidal melanoma, metastasis of this tumor invariably leads to either loss of vision or the eye itself. There are even a few reports on patients with choroidal melanoma that remain unchanged for years, and others who develop metastatic disease after enucleation for the tiniest melanoma.

Additional Resources

https://eyewiki.aao.org/Management_of_Choroidal_Melanoma_and_Ciliary_Body_Melanoma#Management_of_Systemic_Metastasis

References

  1. 1.0 1.1 1.2 1.3 1.4 Damato B. Ocular treatment of choroidal melanoma in relation to the prevention of metastatic death – A personal view. Progress in Retinal and Eye Research. 2018;66:187-199. doi:10.1016/j.preteyeres.2018.03.004.
  2. 2.0 2.1 2.2 Singh P, Singh A. Choroidal Melanoma. Oman Journal of Ophthalmology. 2012; 5(1): 3-9. doi: 10.4103/0974-620X.94718
  3. Carvajal RD, et. al. Metastatic disease from uceal melanom: treatment options and future prospects. The Brititsh Journal of Ophthalmology. 2017 Jan; 101(1): 38-44. doi: 10.1136/bjophthalmol-2016-309034