Retinoblastoma Appears to Be on the Increase in Europe

By Reuters Staff

February 10, 2021

NEW YORK (Reuters Health) - The incidence of retinoblastoma appears to be rising in Europe, a new study suggests.

With a reported incidence of around one per 15,000 to 18,000 live births, retinoblastoma is the most common intraocular malignancy, Dr. Andrew W. Stacey of the University of Washington, Seattle, and colleagues note in Ophthalmology.

Some studies have suggested that numbers have remained stable since the beginning of the century, but a longer-term Finnish study recorded an increase from about one in 16,700 live births in 1990 to one in 12,500 in 2014. However, the researchers note, "The increase in Finland was not evident when familial retinoblastoma was excluded."

Improvements in treatments in higher-income countries, they point out, "are leading to less visual impairment, better eye preservation, and better survival. This has led to a reduction in the coefficient of selection, increased fitness, and an increased percentage of familial retinoblastoma in high income countries."

To see if they could find support for this hypothesis, the researchers aimed to estimate the incidence of retinoblastoma across 40 European countries within a one-year time frame. Treatment centers reported all new cases of retinoblastoma that were diagnosed between January and December 2017.

From the original 40 countries reporting on 517 retinoblastoma patients the researchers deemed that data from 24 countries involving 294 patients were most likely to be complete. Among major countries not included were the Russian Federation, Italy and Germany.

Of those included from the Eastern European Region, numbers of cases ranged from two in Slovakia to 34 in the Ukraine. For Northern Europe these ranged from one each in Latvia and Estonia to 51 in the U.K.

For Southern Europe, Slovenia had one and Spain had 23. And, finally in Western Europe, cases ranged from one in Andorra to 49 in France.

The combined data resulted in an incidence rate of one in 13,915 or 7.2 per 100,000 live births. When country population estimates and birth rates from the World Bank Population Prospects and the United Nations database were used to refine the findings the results were similar.

The incidence was highest in Northern Europe at one per 12,907 live births and lowest in Southern Europe at one per 17,177. There was no significant relationship between incidence rate and gross domestic product. The only variable that resulted in a significant association with incidence rate was the proportion of familial cases.

Thus, the researchers conclude, "As the percentage of familial cases increases, the overall incidence of retinoblastoma should increase. The results of this study document this increase throughout Europe."

They add, "To the best of our knowledge, the increased frequency of carriers of germline RB1 pathogenic variants in Europe illustrates for the first time the selection relaxation effect of therapeutic intervention for a lethal disorder, after only a few generations."

Dr. Stacey did not respond to requests for comment.

SOURCE: Ophthalmology, online January 25, 2021.