Objective: There has been increasing interest in active surveillance of papillary thyroid microcarcinoma. The objective of this study was to characterize the incidence and outcomes of nonoperatively managed differentiated thyroid cancers (DTCs) in California.
Methods: Biopsy-proven DTCs from the California Cancer Registry were linked to data from the California Office of Statewide Health Planning and Development (2004-2012). Low-risk tumors were defined as localized disease measuring <4 cm without extrathyroidal extension, nodal involvement, or distant metastasis.
Results: Of 29,978 patients with DTC, 318 (1.1%) were managed nonoperatively. Compared to operatively managed patients, patients managed nonoperatively were older with more comorbidities, larger tumors (mean size, 2.9 cm vs. 2.0 cm), and an increased rate of distant metastasis (20.4% vs. 3.4%). Independent predictors of nonoperative management included increasing age, larger tumor size, papillary histology, and distant metastases. Of 10,795 patients with low-risk tumors, 161 (1.5%) were managed nonoperatively, with tumor size as follows: <1 cm (15.5%), 1 to 2 cm (50.3%), >2 to 3 cm (24.3%), and >3 to 4 cm (9.9%). There were no disease-specific deaths in the low-risk, nonoperative group (median follow-up [interquar-tile range], 21.3 [5.7 to 51.1] months). The proportion of patients managed nonoperatively remained relatively stable over the study period (mean increase 0.1% per year, P = .09). All P values were <.05 unless otherwise stated.
Conclusion: The vast majority of patients with DTCs are treated surgically, suggesting active surveillance is rarely practiced in California. Although follow-up was limited, no disease-specific mortality in nonoperatively managed, low-risk DTCs was observed.
Abbreviations: CCI = Charlson Comorbidity Index; CCR = California Cancer Registry; CI = confidence interval; DTC = differentiated thyroid cancer; FTC = follicular thyroid carcinoma; HCC = Hürthle cell carcinoma; IQR = interquartile range; mPTC = papillary thyroid micro-carcinoma; OR = odds ratio; OSPHD = Office of Statewide Health Planning and Development; PTC = papillary thyroid carcinoma.