Thyroid cancer in Pacific women in New Zealand

To describe trends in incidence rates of thyroid cancer in New Zealand between 1981-2004 with a particular focus on Pacific women.

Linked census-cancer registration data was used to calculate age standardised cancer incidence rates for thyroid cancer. Both trends over time amongst Pacific women, and differences in rates between Pacific and European/Other women in New Zealand, were assessed.

Rates of thyroid cancer in New Zealand were higher for women than men. The highest rates of thyroid cancer in were observed amongst Pacific women with a pooled age-standardised incidence rate of 18.5/100,000 (95%CI 14.6-22.4/100,000) compared to 5.2/100,000 (95% 4.8-5.5/100,000) for European/Other; SRR 3.58 (95%CI 2.87-4.47). Sparse data mean it is difficult to clearly identify a trend over time for Pacific women but European women experienced a 73% increase from 4.0/100,000 (95%CI 3.3-4.6/100,000) in 1981=1986 to 6.9/100,000 (95%CI 5.9-7.8/100,000) in 2001-2004 (Ptrend=0.05).

Pacific women in New Zealand have the highest rates of thyroid cancer among resident ethnic groups. Risk was highest for Pacific women over 45 years of age. More research needs to be done looking at which specific ethnicities are driving rates of thyroid cancer in New Zealand and whether the risk is influenced by birthplace and age at migration to New Zealand.