Clinicopathological Features and Prognostic Outcome of Poorly Differentiated Thyroid Carcinoma: 10 -Year Experience in a Tertiary Care Institute at South India

Introduction: Poorly differentiated thyroid carcinoma (PDTC) is a rare malignancy which accounts for only 1 to 15% of all thyroid cancers. There is only limited literature on PDTC regarding its clinical behavior and treatment consensus, and there was no published data from south Indian population.

Aim: To study the clinicopathological characteristics, treatment and prognostic outcome of PDTC cases treated in our institute.

Materials and Methods: This is a retrospective study over a period of 10 years from 2005 to 2014 at Department of Endocrine surgery, Madras medical college, a tertiary referral center in South India. The following data were collected from medical records: demographics, clinical presentation, treatment given, histopathological characteristics and the clinical outcome of all PDTC cases diagnosed based on Turin’s criteria. The data were analyzed, and statistical analysis was performed.

Results: Among 626 thyroid malignancies, only 19 cases of PDTC were treated during the study period. The median age of presentation was 54 years, of which 17 were females, and 2 were males. All patients have presented with goiter with a median duration of 6 years. Total thyroidectomy was performed in all cases, and three patients had neck dissection along with total thyroidectomy. The predominant histological subtype was the insular pattern. The cervical lymph node metastasis was seen in 3 cases (15.8%). The distant metastatic rate was 68.4% of which 9 cases had lung and 4 had bone metastasis. Adjuvant radioiodine therapy was given only in 2 patients (10.5%) and the majority received external beam radiotherapy (89.5%). The overall 5-year survival rate was 36%.

Conclusion: Poorly differentiated thyroid cancer is aggressive and rare thyroid cancer. The prevalence rate in our study population was 3%. The tumor behavior in our study population was more aggressive than that of other regions. Surgery remains the mainstay of treatment in the control of loco regional disease. EBRT was the primary form of adjuvant therapy in our study population which showed a better survival advantage than RAI. More extensive studies are required regarding consensus for adjuvant therapy and optimal management of PDTC.