Frequent CT scan linked to secondary cancers
Washington: Older men with early-stage testicular cancer who opt for surveillance with regular CT scans over lymph node removal are at greater risk for secondary cancers, according to a new study.
The findings indicate that physicians should consider the risk of new cancers with surveillance when discussing treatment options with their patients.
Along with a multi-disciplinary team of UC Davis researchers, Karim Chamie, a UC Davis urology resident at the time of the study, examined the cases of 7,301 men diagnosed between 1988 and 2006 with nonseminomatous germ cell tumor, the most common type of testicular cancer.
Chamie and his colleagues wanted to know if, after initial surgery, frequent computed tomography (CT) imaging of men to check for new signs of the disease increased the rate of secondary tumor growth.
"This is the first study that I am aware of that shows that diagnostic CT scans cause cancer with statistical significance," said John Boone, professor in the Department of Radiology at UC Davis, study co-author and internationally known CT expert.
Chamie`s research found that more patients who have been on active surveillance will be diagnosed with secondary malignancies after 15 years than will patients who received aggressive lymph node surgery or chemotherapy.
Statistical analysis determined that of 10,000 patients put on active surveillance, 306 would get secondary malignancies, versus 233 if they had the surgery alone.
That translates into 73 additional secondary malignancies. And while 73 may not seem like a big number, of the men who underwent surgery, only 50 died of testicular cancer.
"The side effect is worse than the disease. More men are likely to get secondary malignancies than are liable to die from their active disease," Chamie said.
What surprised Chamie and the other researchers is that the risk of secondary cancers after repeated CT scans was more significant in older men than in younger men. Chamie suspects that is because younger bodies can more easily repair DNA damage caused by radiation exposure.
The study was published online last week in the journal Cancer.