Deaths due to differentiated thyroid cancer: a South Island, New Zealand experience: 1984-2009.

Aim: To assess differentiated thyroid cancer (DTC) deaths from the northern half of New Zealand's South Island.

Methods: Retrospective review of Christchurch Hospital Thyroid Clinic and Oncology Department clinical records of resident patients who died of differentiated thyroid cancer of follicular cell origin over the 25-year period 1984-2009.

Results: During the 25-year study period 25 patients died from differentiated thyroid cancer. All patients (17 female, 8 male) were Caucasian, with median age 65 years (47-86 years) at presentation. Most (24/25) patients presented with advanced (15 Stage IV, 9 Stage III) disease. Three patients initially presented with cervical lymphadenopathy and four patients with distant metastases--three patients with bone metastases, and one with a pleural effusion. The pathological classification of the tumours included 14 papillary cancers (four were follicular variants), six follicular cancers and five Hurthle cell cancers. The majority of primary tumours were large (>4 cm) and 11 were locally invasive. However one patient had a small (1.3 cm) papillary cancer and presented with a pleural effusion. Surgical removal of the primary tumour was attempted in 24 of the 25 patients, 18 received postoperative radioiodine 131I therapy, and three had external beam radiation therapy. The median survival from diagnosis was 5.5 years (0.2-22 years) with two Stage IV patients (both with Hurthle cell cancers) dying within 4 months. The majority of patients died of metastatic disease but seven died of local disease.

Conclusions: During the 25-year study period, 25 patients died of differentiated thyroid cancer which approximates to one DTC death per year in our region. The median age at diagnosis was 65 years with no patients <45 years of age, and the female to male ration was 2.1:1. Most patients presented with advanced disease--7 patients (28%) had distant metastases. Hurthle cell cancers were over-represented (20%) in our series.