50th Annual Meeting of the American Society of Clinical Oncology (ASCO):

Younger Age Associated with Higher Risk of Recurrence in Nonmetastatic Papillary Thyroid Cancer

Among patients with nonmetastatic papillary thyroid cancer (PTC), those younger than age 25 appear to have a higher risk of recurrence than their older counterparts, according to results of a retrospective analysis.

The findings were presented in a poster session on May 31 at the 2014 Annual Meeting of the American Society of Clinical Oncology in Chicago, Illinois.

Characteristics of Recurrence
The higher risk of recurrence in younger patients may be in part due to larger tumor sizes and the presence of aggressive histopathologic features, noted study author Iris H. Wei, MD, and her colleagues, in their presentation.

To evaluate characteristics associated with risk of recurrence, Dr. Wei, of the University of Michigan, and colleagues reviewed the records of 623 patients with papillary thyroid cancer (PTC) who had undergone complete surgical resection at the University of Michigan between 2006 and 2012. The patient group was predominately female (77%) with a median age of 49 years (range, 10-87 years). Patients with documented distant metastases were excluded from the analysis.

Patient Follow-up
After an average follow-up period of 2.5 years, 3.2% of patients developed a recurrence. The recurrences were all locoregional in the central or lateral neck and were detected after an average of 1.2 years after surgery. Of the 20 patients with recurrence, one patient received treatment with radioactive iodine and the remaining 19 patients underwent another surgery.

The researchers found that certain clinical and pathologic factors were associated with a significant risk of recurrence, including larger tumors, presence of capsular invasion, presence of vascular invasion, presence of extrathyroidal extension, presence of lymph node metastases, and presence of extranodal extension.

Overall, patients with any of these aggressive pathologic features, were more than 15 times more likely to develop recurrence than patients without these features (hazard ratio [HR], 15.7; P < .0001).

Multivariate Analysis
In a multivariate analysis, the two factors that remained statistically significant for predicting PTC recurrence were tumor size (HR per cm, 1.37; 95% confidence interval [CI], 1.08-1.72; P = .009) and presence of capsular invasion (HR, 6.94; 95% CI, 1.51-31.98; P = .013).

The researchers also evaluated the risk of recurrence according to age, noting that all cases of PTC in patients younger than 45 years without evidence of distant metastases are classified by the AJCC as Stage I based on the better outcomes in this group.

Dr. Wei and colleagues found no significant difference in recurrence rate between patients younger than age 45 and those age 45 or older. However, additional analyses of outcomes by age found that the youngest patients—those younger than age 25—were substantially more likely to have disease recurrence than those older than age 25; the trend was nearly statistically significant (HR, 2.67; P = .05). A comparison of the histopathological features of PTC according to age found that patients younger than age 25 were significantly more likely than older patients to have vascular invasion, lymphatic metastases, and extranodal extension (P < .001 for each).

The researchers concluded that young patients with these risk factors should be closely postoperatively so any recurrence that does occur can be detected and treated as early as possible.

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