The research, conducted out of the Mayo Clinic in Rochester, Minn., looked at approximately 900 papillary thyroid microcarcinoma patients from 1945 to 2004. The study looked at the impact various treatment approaches had on the risk of thyroid cancer recurrence and mortality, based on computerized data that had been maintained about the patient population. For example, some patients in the group received radioiodine remnant ablation.
The most important finding was that among 892 patients who had their thyroid tumors removed, none had any spread of the cancer during the 20 years after the surgery. The 20-year and 40-year recurrence rates for thyroid tumors were 6 and 9%. Of the entire study population, only 3 patients (0.3%) died of papillary thyroid microcarcinoma, and the survival and mortality rates for the study group did not differ significantly from the control population. Interestingly, the risk of recurrence did not appear to be significantly improved by radioiodine remnant ablation treatment.
The researchers concluded that their findings confirm the following:
- Papillary thyroid microcarcinoma has an excellent prognosis if the primary tumor is completely removed during surgery.
- More than 99% of patients with papillary thyroid microcarcinoma are at no risk of a distant spread of the cancer or of dying of thyroid cancer.
- Neither total thyroidectomy (total surgical removal of the entire thyroid) nor postoperative radioiodine remnant ablation improved the patient outcome -- risk of tumor recurrence or death from papillary thyroid cancer -- over a 40-year period.
Implications for PatientsThe incidence of microcarcinoma is increasing, primarily due to better detection. These small, asymptomatic tumors tend to be detected during ultrasounds and X-rays of the head and neck areas. Experts are looking to determine, though, what treatment will provide the best possible outcome, without providing unnecessary additional treatment. Some doctors already forego radioiodine remnant ablation for papillary thyroid cancer patients with small tumors, and it's likely that as more studies confirm these findings, the standard of care will shift further away from radioiodine for these patients.
Source: Hay, Ian et. al. "Neither total thyroidectomy nor radioiodine remnant ablation improved long-term outcome in 900 patients with papillary thyroid microcarcinoma treated during 1945 through 2004," Endocrine Abstracts (2008) 16 P685 Online