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NEW YORK (Reuters Health) - Childhood cancer survivors are at a four-fold increased risk of developing new cancers of the bladder later in life, new research shows.
But their risk is still very small; based on the findings, fewer than one-half of a percent of all childhood cancer survivors will be diagnosed with bladder cancer by age 55.
About three-quarters of children diagnosed with cancer will survive for at least five years, Dr. Clare Frobisher of the University of Birmingham in the UK and her colleagues note in BJU International. These individuals are known to be at higher risk of developing a new cancer later on.
To investigate the specific risk associated with bladder cancer, Frobisher and her team looked at nearly 18,000 people diagnosed with childhood cancer in the UK between 1940 and 1991 who had survived for at least five years after their cancer diagnosis. Seventeen had been diagnosed with bladder cancer during follow-up, about four times as many as would be expected in the general population.
The highest risk was seen in patients who had initially developed heritable retinoblastoma, a rare type of eye cancer mainly seen in children younger than five. Survivors of this type of cancer were more than nine times as likely to develop bladder cancer as childhood cancer survivors overall.
Chemotherapy upped the likelihood of bladder cancer about four-fold. But again, the risks were still small; about four in every 100,000 childhood cancer survivors would develop bladder cancer in a given year; 34 of every 100,000 retinoblastoma patients would.
While following all childhood cancer survivors for bladder cancer would be impractical, given the rarity of the disease, the researchers say, it may be warranted in heritable retinoblastoma survivors and others with a genetic tendency to develop tumors.