ATA Guidelines Tools

3 Response to Therapy (see Recommendation 29 and Table 9) ➤ Response assessment is performed after intervention, either for initial or clinically persistent/recurrent disease. • Excellent response: No biochemical or structural evidence of persistent thyroid cancer (i.e., remission). • Indeterminate response: The presence of non-specific findings on imaging ; mildly elevated serum Tg levels; or positive, but stable or declining, anti- thyroglobulin antibody (TgAb) levels in persons who have undergone total thyroidectomy with or without RAI. Most patients in this category prove to have a "good" clinical response to therapy, especially if they have a low risk of clinical recurrence, and findings are nonspecific. However, those at intermediate- or high-risk of clinical recurrence based on histopathologic and staging characteristics in this category may have higher rates of recurrence. • Biochemically incomplete response: Elevated serum Tg concentrations or rising TgAb levels without radiologic evidence of structural recurrence in persons who have undergone total thyroidectomy with or without RAI. • Structurally incomplete response: Structural evidence of disease recurrence (by imaging or biopsy), usually in conjunction with elevated Tg and/or TgAb levels. Persistent or Recurrent Disease (see Recommendation 29 and Table 9) ➤ Clinically persistent disease: Biochemical or structural evidence of disease within 90 days of initial therapy (or intervention for persistent disease). ➤ Clinically recurrent disease: Biochemical or structural disease subsequently identified in patients previously deemed to have an excellent response following therapy. Clinically recurrent disease likely represents progression of residual disease that is below the lower limits of detection. Risk of Recurrence (Figure 2) ➤ We use the term "recurrence" to mean clinical recurrence, recognizing that most recurrences reflect growth of residual disease to clinically detectable levels. An overall assessment of risk of biochemical or structural recurrence determined by incorporating a combination of factors: histopathologic characteristics of the resected tumor, American Joint Committee on Cancer (AJCC) staging, imaging, molecular analysis of tumor, and response to therapy at subsequent evaluation. For the purpose of these guidelines, categories are designated as low (<10%), low-intermediate (10–15%), intermediate-high (≥16–30%), and high (>30%) risk of recurrence.

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