{'fraction_non_alphanumeric': 0.04127411395244504, 'fraction_numerical': 0.03275011215791835, 'mean_word_length': 4.837696335078534, 'pattern_counts': {'":': 0, '<': 4, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Clinical and oncological features of children and young adults with multiple endocrine neoplasia type 2A.

BACKGROUND
RET genotype analysis allows identification of asymptomatic carriers at risk of developing medullary thyroid carcinoma (MTC). However, there is still controversy regarding the ideal timing and extent of prophylactic thyroidectomy due to the wide spectrum of clinical presentation. Surveillance of a large number of young patients is crucial to advance our understanding of the natural course of the disease. This study aimed to describe the clinical presentation, oncological features, and treatment outcome of children and young adults harboring RET mutations followed at our institution from 1997 to 2007.


METHODS
Forty-one individuals aged < or =25 years from 17 independent multiple endocrine neoplasia type 2A kindred were studied. Twenty-one individuals presented with thyroid nodules at diagnosis, and 20 were disease free at physical examination.


RESULTS
Preoperative basal calcitonin levels were elevated in 85.7% of patients with clinical disease and in 54.5% of asymptomatic carriers. Thyroid ultrasonography (US) showed one or more nodules in 69.0% of the patients. A positive correlation between age at surgery and tumor-node-metastasis (TNM) stages was observed (p < 0.001). None of the patients under 15 years of age presented lymph node or distant metastasis. After a follow-up of 4.4 +/- 1.4 years all asymptomatic patients were disease free based on physical examination, cervical US, and undetectable serum calcitonin levels. In the group of patients with clinical disease, 47.6% have persistent disease (follow-up of 12.0 +/- 5.9 years). Indeed, palpable thyroid nodule at diagnosis was significantly associated with persistent disease (p < 0.001, odds ratio [OR] 1.9, 95% confidence interval [CI 95%] 1.27-2.87). Of note, none of the patients who presented lymph node metastasis at diagnosis were cured by surgical intervention (p < 0.001, OR 5.0, CI 95% 1.45-17.0).


CONCLUSION
Our data show a time-dependent MTC progression. The presence of a palpable thyroid nodule and lymph node metastasis at diagnosis was associated with persistent or recurrent disease after surgical procedure.