Shortening the time from first appearance of symptoms to diagnosis has no bearing on survival or stage of disease in unilateral retinoblastoma, the most common form of childhood eye cancer, according to a new study.

Retinoblastoma is easily detected by shining a light into a child’s eye—often as a cat’s eye reflection revealed through flash photography. As a result, a number of countries, particularly resource-poor countries where the disease is more prevalent, have initiated education and screening programs, thinking that catching the disease early would lead to improved outcomes.

This study is the first to follow a cohort of children with the disease over time and to look at the unilateral (one eye) and bilateral (both eyes) forms of the disease separately. It was conducted by researchers at Columbia University Mailman School of Public Health in New York, New York, in partnership with the Hospital Infantil de Mexico Federico Gomez in Mexico City.

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“Our study suggests that screening children for retinoblastoma may not improve outcomes for the majority of patients, particularly for the more common form of the disease affecting one eye,” said senior author Manuela A. Orjuela, MD, ScM, of Columbia University. “By the time the tumor is visible in the child’s eye, vision is infrequently salvageable, and removal of the eye is usually necessary to prevent spread of the disease.”

The research team followed 179 children with retinoblastoma in Mexico City and interviewed their parents about symptoms and socio-demographic factors, along with assessing disease stage with several validated methods. The study was published in Cancer Epidemiology, Biomarkers & Prevention (2014; doi:10.1158/1055-9965.EPI-13-1069).

The researchers found that for unilateral disease, the lag-time between when parents first noticed the disease and when the children were diagnosed had no bearing on disease stage or survival. In the more rare bilateral disease, a longer lag time was strongly associated with a more advanced stage and worse prognosis, but it did not predict the extent of disease involvement in the more affected eye. Lag times averaged 7 and 8 months for unilateral and bilateral disease, respectively.

“Retinoblastoma is usually thought of as one disease. But there is good evidence that unilateral and bilateral retinoblastoma are distinct and progress in different ways,” said Orjuela.

“There is also significant variation in how tumors respond to treatment, no matter how soon we initiate therapy,” said first author Marco A. Ramírez-Ortiz, MD, chief of the department of Ophthalmology at the Hospital Infantil de México.

Intriguingly, the researchers found that stage and survival in both forms of retinoblastoma were predicted by the mother’s education level. Mothers with less formal schooling had children with significantly higher stage disease and significantly worse survival.

The child’s home environment may be another contributing factor. Children born in homes with dirt floors had more advanced disease than their peers with different housing conditions, even after taking family income into account, possibly because they were exposed to metal or some toxin in the dirt.