Enhanced diagnostic tools bump thyroid cancer stats

Researchers say more sophisticated detection methods-not a change in disease occurrence-account for a dramatic increase in thyroid cancer over the last 30 years.

Drs. Louise Davies and H. Gilbert Welch from Dartmouth Medical School and Veteran Affairs, respectively, reviewed data from the Surveillance Epidemiology and End Results and the National Vital Statistics System. They sought to explain a thyroid cancer incidence rise from 3.6 per 100,000 in 1973 to 8.7 per 100,000 in 2002 (JAMA 2006;295:2164-2167). Though they found no significant change in incidence of the less common histological types, they did find the detection of papillary cancers 2 cm or smaller had grown almost threefold in the same period.

The use of ultrasound and fine-needle aspiration boomed in the 1980s and 1990s, enabling detection of very small thyroid nodules. Physician self-referral may also be a contributing factor to increased detection, the researchers said.

"Given the known prevalence of small asymptomatic papillary thyroid cancers at autopsy, we believe this suggests that increased diagnostic scrutiny has caused an apparent increase in incidence of cancer rather than a real increase," the authors said.

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