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People with common thyroid cancers may not need immediate treatment, study says

May 17, 2010 |  4:21 pm
Most people with small, barely detectable tumors of the thyroid gland do not need immediate treatment, and their survival rate is nearly as good as the rate for those who do seek such treatment, researchers reported Monday. Critics of the study conceded that watchful waiting is, in fact, appropriate for many such patients but noted that even a small decrease in survival can mean many additional deaths when translated over large numbers of patients.

The diagnosis of thyroid cancer has been growing markedly, with a three-fold increase over the last three decades. Almost all of that increase is the result of the detection of such small, localized tumors, that are not normally apparent by palpation but that can be observed with sophisticated imaging techniques.

Autopsy studies also show that small thyroid cancers are present in most people who died from other causes, a finding similar to the observation of small prostate tumors in most men who die of other causes. Such findings suggest that most thyroid tumors (and prostate tumors) are a benign side effect of aging that can be safely ignored unless they suddenly start growing. Dr. Louise Davies and Dr. H. Gilbert Welch of the Dartmouth Institute for Health Policy and Clinical Practice in Hanover, N.H., and the Veterans Affairs Medical Center in White River, Vt., compiled data from a national registry on 35,653 patients who were diagnosed with such small tumors, called papillary thyroid cancer, between 1973 and 2005; 440 of the patients did not undergo immediate treatment, which generally involves surgical removal of all or part of the thyroid gland.

Davies and Welch reported in the journal Archives of Otolaryngology--Head & Neck Surgery that, after six years of follow-up, 141 of the treated patients, less than half a percent, had died, compared to six of the untreated patients, or 1.4%. They projected that the 20-year survival rate for treated patients would be 99%, while that for untreated patients would be 97%. They concluded that "papillary thyroid cancers of any size that are confined to the thyroid gland have no lymph node metastases at presentation and do not [reach beyond the thyroid gland] are unlikely to result in death due to the cancer." That increase in deaths, they said, is offset by the increased risk of side effects from cancer surgery, which can include permanently low levels of thyroid hormones and significant damage to laryngeal function.

In an editorial accompanying the report, however, Dr. Erich M. Sturgis and Dr. Steven I. Sherman of the University of Texas M.D. Anderson Cancer Center said, in effect, "Hold on just a moment!"  While 2 percentage points is a very small difference, they agreed, when extrapolated to the 35,000 patients diagnosed with thyroid cancer each year, that could mean an extra 500 to 700 deaths. "Certainly, most of those hypothetical 500 to 700 people would have wished their physicians had offered them the treatment that had 'statistically' better survival." Some people can be simply observed, they said, but they have to be very carefully selected.

-- Thomas H. Maugh II