Favorable outcomes seen for lung-only metastatic thyroid cancer

Results of a retrospective study conducted in South Korea demonstrated that most patients with metastatic differentiated thyroid cancer confined to the lungs had favorable outcomes.

“Differentiated thyroid carcinomas, which include papillary thyroid carcinoma and follicular thyroid carcinoma, have favorable long-term survival. However, distant metastases occur in 7% to 23% of patients with [differentiated thyroid carcinomas] and represent the most common cause of thyroid cancer-related death,” Jae Hoon Chung, MD, PhD, of the division of endocrinology and metabolism at Samsung Medical Center and Sungkyunkwan University School of Medicine, and colleagues wrote.

The researchers added that the lungs are the most common locations of metastases in patients with differentiated thyroid cancer.

“However, few previous studies have investigated long-term outcomes and prognostic factors in patients with only lung metastasis,” they wrote.

Chung and colleagues performed a retrospective study of 89 patients treated for differentiated thyroid cancer with lung-only metastases at Samsung Medical Center between 1996 and 2012. The researchers evaluated progression-free survival and cancer-specific survival rates, and used Cox regression analysis to find factors linked with cancer-specific death and structural progressive disease.

Median follow-up was 84 months. The 5-year cancer-specific survival rate was 78%, and the 10-year rate was 73%, the researchers reported. Radioactive iodine (RAI) non-avidity, late or preoperative diagnosis of metastasis, age at least 55 years at diagnosis and macro-nodular metastasis were all associated with poorer progression-free survival and cancer-specific survival, Chung and colleagues wrote.

Older age (P = .002), as well as RAI non-avidity (P = .045) and preoperative (P = .03) or late (P = .026) diagnosis were all independently predictive of structural progressive disease, the researchers reported, while RAI non-avidity was also predictive of cancer-specific mortality (P = .025).

The study was limited by its retrospective nature, Chung and colleagues wrote.

“In conclusion, patients with [differentiated thyroid cancer (DTC)] and metastatic tumors limited to the lungs showed relatively favorable outcomes in this study,” the researchers wrote. “The major factors determining prognosis in metastatic DTC limited to the lungs were age, RAI and timing of metastasis diagnosis. Younger patients with RAI avid metastasis or metastasis detected during the initial RAI treatment had better a better prognosis.” – by Andy Polhamus

Disclosures: The authors report no relevant financial disclosures.