[Papillary thyroid microcarcinoma. Long-term outcome in 587 cases compared with published data]

Area of Science:

• Endocrinology
• Oncology
• Surgical Pathology

Background:

• Papillary thyroid microcarcinoma (PTMC), defined as a tumor ≤1 cm, is the most common thyroid malignancy.
• Distinguishing between PTMC subtypes is crucial for determining appropriate treatment strategies and predicting patient outcomes.

Purpose of the Study:

• To evaluate the long-term outcomes of surgical treatment for PTMC.
• To differentiate therapy options based on disease progression risk by comparing institutional data with existing literature.

Main Methods:

• Analysis of 587 PTMC cases surgically treated between 1990 and 2006.
• Patients were categorized by PTMC diameter (<5 mm vs. ≥5 mm) and type (incidental, diagnosed, occult with metastasis).
• Prognostic factors including patient demographics, surgical extent, lymph node status, and adjuvant therapy were compared against tumor size.

Main Results:

• Significant differences were observed in PTMC type, thyroidectomy extent, lymph node metastasis, 131-I therapy, survival, and recurrence rates between tumor size groups.
• Excluding occult PTMC with metastasis, patients with PTMC <5 mm showed no recurrence after treatment.
• No reoperations were needed for PTMC <5 mm without metastasis.

Conclusions:

• The term "microcarcinoma" may be misleading due to differing behaviors of PTMC subtypes (incidental, diagnosed, occult with metastasis).
• Partial thyroidectomy is a suitable treatment for PTMC <5 mm without lymph node involvement.
• Occult PTMC with metastasis warrants aggressive management comparable to larger thyroid tumors due to its significant prognostic implications.