Papillary carcinoma of the thyroid: hereditary or radiation-induced?

Role of Age at Diagnosis in Defining Potential Familial Nonmedullary Thyroid Cancer in Kindreds With Two Affected Members

CONTEXT

The definition of familial nonmedullary thyroid cancer (FNMTC) in 2 or more first-degree relatives is controversial due to the high probability of observing a sporadic association when only 2 members of first-degree relatives are affected.

OBJECTIVE

To evaluate the role of age at diagnosis in differentiating the true cases of FNMTC.

DESIGN, SETTING, PARTICIPANTS, AND MAIN OUTCOME

From a group of 721 papillary thyroid cancer (PTC) patients, 95 familial PTC (FPTC) patients with 2 first-degree relatives have been identified. They were split in 2 groups: Group 1 consisted of both the proband and the affected relative, with age at diagnosis ≤ 45 years; Group 2 consisted of proband and/or the affected family member, with age at diagnosis > 45 years. The clinical-pathological features and outcome of both FPTC groups were compared with 626 sporadic PTC patients (SPTC).

RESULTS

Familial PTC patients with age at diagnosis ≤ 45 years, compared with the matched group of sporadic PTCs, had a more frequent multifocal, bilateral, and extrathyroidal extension of tumor and showed worse outcome. No differences were found between FPTC and SPTC patients with age > 45 years. At multivariate analysis, distant metastases, American Thyroid Association (ATA) risk, and FPTC ≤ 45 years were independent predictors of outcome.

CONCLUSIONS

Based on the observation that PTC is more aggressive when the diagnosis is made in 2 family members, both with age < 45years, we suggest that the definition of FPTC in kindreds with 2 affected members should also take into account the age at diagnosis as a key element of familial cancer.

Familial papillary carcinoma of the thyroid

A 38-year-old woman had bilateral papillary thyroid carcinoma. Her brother and mother also had papillary thyroid carcinoma. The literature on familial papillary thyroid carcinoma is reviewed briefly.