BACKGROUND
Thyroid cancer is the fastest rising cancer in the United States. There are 2 main types of thyroid cancer: papillary (most common) and follicular. Response to therapy for both types is usually excellent and >95% of patients with thyroid cancer do well and survive their thyroid cancer.

Currently papillary and follicular thyroid cancer is staged using the same criteria. This helps predicts survival from thyroid cancer. Age is included in the staging criteria as older age is a known risk factor for increasing risk of death in thyroid cancer. Recently the age cutoff for “old” was changed from 45 to 55 years of age, which has led to better risk predictors of death. However, papillary and follicular cancers have a somewhat different clinical course and the same age cutoff may not be appropriate for both disease. Therefore, this study examined if there should be a different age cutoff for the two different types of thyroid cancer.

THE FULL ARTICLE TITLE
van Velsen EFS et al 2021 Finding the optimal age cutoff for the UICC/AJCC TNM staging system in patients with papillary or follicular thyroid cancer. Thyroid. Epub 2021 Mar 4. PMID: 33487121

SUMMARY OF THE STUDY
All patients in two large databases in the Netherlands and Germany that had thyroid surgery for cancer and complete survival and pathology data were analyzed to find the best age cutoff for “old” for thyroid cancer staging. Age cutoffs were analyzed at 5-year increments from 20 up to 85 years and by 1-year increments between 35 and 55 years.

In over 3000 patients, 2355 (77%) had papillary thyroid cancer and 719 (23%) had follicular thyroid cancer, with an average follow-up of 84 months. The average age was 48.7 years, and 69.5% were female. When compared to patients with papillary thyroid cancer, patients with follicular thyroid cancer were older (54.2 years vs. 47.1 years), more likely to be male (37.1% vs. 28.5%), less likely to have spread of the cancer to the lymph nodes (9.2% vs. 27.3%) and more likely to have spread of the cancer outside of the neck (18.2% vs. 6.0%). Overall, this population showed that an age cutoff for “old” of 50 years seemed best for patients with papillary thyroid cancer, and 40 for patients with follicular thyroid cancer.

WHAT ARE THE IMPLICATIONS OF THIS STUDY?
This study suggests that there should be different staging cutoffs for papillary and follicular thyroid cancer and a younger age cutoff should be used over what is currently in the most updated staging system. This is important for patients in that the age cutoff may be fluid in that 40-55 year old range. Since a hard cutoff can drastically change staging, the physician should discuss this with patients. Moreover, a lower age cutoff should likely be used for patients with follicular cancer, which may upstage some previously staged I and II to a more advanced stage with an increased risk of death. These patient may benefit from more aggressive treatments.

—Melanie Goldfarb, MD

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