Surgeon: 'Rule of fives' helps predict choroidal lesion metastasis risk

PHILADELPHIA — Using the "rule of fives" can aid physicians in counseling patients with small melanocytic lesions on their prognosis. It can also help in making treatment decisions, according to an ocular oncologist speaking here.

The "rule of fives" is a probability model that uses factors to gauge the risk of lesion metastasis. The risk factors include tumor thickness greater than 2 mm, documented tumor growth, its proximity to the optic disc and patient symptoms, said Jerry A. Shields, MD. He presented the results of a study evaluating the model at the 2007 Wills Eye Hospital Annual Alumni Conference.

Growth and metastasis of small melanocytic choroidal lesions are rare, and most patients have an "excellent" prognosis, he said, noting that other types of ocular melanomas are diagnosed earlier. But early diagnosis and treatment of such choroidal lesions are critical for a good patient prognosis, he said.

In their study, Dr. Shields and colleagues found a 3% metastasis rate among 1,329 patients treated for such lesions.

Among patients with no risk factors, less than 1% developed metastases. The rate of lesion metastases increased to 5% among patients with one risk factor, to 10% among those with two risk factors, to 15% among those with three risk factors and to 20% among those with four risk factors, Dr. Shields said.

Treatment is generally indicated for patients with two to three risk factors, depending on the clinical circumstances, according to the study abstract.