Second Primary Papillary Thyroid Carcinoma: Insights From Competing Risk Analysis and Post-RAIT

Area of Science:

• Oncology
• Endocrinology
• Cancer Survivorship

Background:

• Rising cancer survival rates increase focus on second primary malignancies (SPMs).
• Papillary thyroid carcinoma (PTC) is a frequent SPM, particularly in cancer survivors.
• Understanding second primary PTC (2-PTC) and its treatment is crucial.

Purpose of the Study:

• To analyze the clinicopathological features and survival of 2-PTC patients.
• To evaluate the effectiveness of postoperative radioactive iodine therapy (post-RAIT) for intermediate-risk 2-PTC.
• To assess the impact of post-RAIT on mortality in 2-PTC patients.

Main Methods:

• Utilized the SEER-17 database (2004-2019) for 6399 2-PTC patients (Cohort 1) and 1743 (Cohort 2).
• Employed competing risk regression models to analyze mortality risks.
• Applied propensity score matching and inverse probability treatment weighting for robust analysis.

Main Results:

• 2-PTC patients were predominantly older, female, and white, with common prior malignancies including breast, prostate, and skin cancer.
• 2-PTC had lower cumulative mortality than prior primary malignancies or other causes.
• Post-RAIT did not significantly reduce mortality in intermediate-risk 2-PTC patients, regardless of age, stage, or prior malignancy status.

Conclusions:

• Second primary papillary thyroid carcinoma generally has a favorable prognosis.
• Postoperative radioactive iodine therapy shows no significant mortality benefit in intermediate-risk 2-PTC.
• Current use of post-RAIT for intermediate-risk 2-PTC warrants reevaluation.