Stage migration with the new American Joint Committee on Cancer (AJCC) staging system (8th edition) for differentiated thyroid cancer

Background

Tumor, node, and metastasis staging in thyroid carcinoma is important for assessing prognosis. However, patients with stage III or IV disease have an overall survival rate of 90%. The change to 55 years of age as the cutoff will create stage migration and many patients will be downstaged.

Methods

We reviewed our database of 3,650 patients to analyze the impact of the new American Joint Committee on Cancer staging system. There were 994 men (27%) and 2,656 women (73%). The median age was 46 years. Patients were staged using both 7th and 8th editions, with a cutoff of 55 years of age and new definitions of T3 and T4, and nodal staging.

Results

Of 3,650 patients, 1,057 (29%) were downstaged. There were 104 (10%) who went from stage IV to I, 109 (10%) who went from stage IV to stage II, and 68 (6%) who went to stage III. There were 218 (21%) who went from stage III to I, 347 (33%) who went from stage III to stage II, and 211 (20%) who went from stage II to I. The overall disease-specific and relapse-free survival was analyzed and showed better stratification with the new staging system.

Conclusion

The new staging system reflects more appropriately the biology of thyroid cancer and will have significant impact on the management of thyroid cancer.