Most patients survive common thyroid cancer regardless of treatment

Papillary thyroid cancer is commonly found on autopsy among individuals who died of other causes, according to background information in the article. "Studies published as early as 1947 demonstrated it, and more recently, a report has shown that nearly every thyroid gland might be found to have a cancer if examined closely enough," the authors write. "The advent of ultrasonography and fine-needle aspiration biopsy has allowed many previously undetected cancers to be identified, changing the epidemiology of the disease. Over the past 30 years, the detected incidence of thyroid cancer has increased three-fold, the entire increase attributable to papillary thyroid cancer and 87% of the increase attributable to tumors measuring less than 2 centimeters."

Louise Davies, M.D., M.S., of Dartmouth Medical School, Hanover, N.H. and Gilbert Welch, M.D., M.P.H., both also of Department of Veterans Affairs Medical Center, White River Junction, Vt., and The Dartmouth Institute for Health Policy and Clinical Practice, Hanover, studied cancer cases and individual treatment data from National Cancer Institute registries. They then tracked cause of death through the National Vital Statistics System.

The researchers identified 35,663 patients with papillary thyroid cancer that had not spread to the lymph nodes or other areas at diagnosis. Of these, 440 (1.2 percent) did not undergo immediate, definitive treatment. Over an average of six years of follow-up, six of these patients died of their cancer. This was not significantly different from the rate of cancer death among the 35,223 individuals who did undergo treatment (161 over an average of 7.6 years of follow-up).

The 20-year survival rate from cancer was estimated to be 97 percent for those who did not receive treatment and 99 percent for those who did. "These data help put management decisions about localized papillary thyroid cancer in perspective: papillary thyroid cancers of any size that are confined to the thyroid gland, have no lymph node metastases at presentation and do not show extraglandular extension [reach beyond the thyroid gland] are unlikely to result in death due to the cancer," the authors write.

"Thus, clinicians and patients should feel comfortable considering the option to observe for a year or longer cancers that fall into this category," they conclude. "When treatment is elected, the cancers in this category can be managed with either hemithyroidectomy [removal of part of the thyroid] or total thyroidectomy [removal of the complete gland], and the prognosis will be the same."