Changing patterns of thyroid cancer in Sri Lanka. Has the iodination programme helped?

OBJECTIVES To ascertain if there has been a change in the pattern of thyroid cancer in Sri Lanka. If so, whether there is a correlation to the implementation of the programme of iodination. DESIGN Retrospective (1974-1986) and prospective (1987-2001). SETTING Kandy Hospital (1974-1982), Peradeniya Hospital (1982-2001) and private hospitals in Kandy (1979-2001). METHOD Three hundred consecutive patients with cancer of the thyroid seen over 28 years (1974-2001) period were reviewed for demography, histopathology and extent of spread at presentation. Seventy one patients of this group had a pre-existing goitre of greater than 10 years' duration and were similarly reviewed. RESULTS A highly significant reduction of anaplastic thyroid cancer and a highly significant reduction in the extent of extra-thyroidal spread at presentation of differentiated thyroid cancer were observed after 1995. In malignancy supervening on pre-existing goitre, a significant reduction in anaplastic carcinoma and a highly significant increase in papillary carcinoma were noted in the post-1996 period. A significant reduction of extra-thyroidal spread was also observed. CONCLUSION A trend towards more differentiated thyroid cancer with lesser degree of spread was observed in recent years. The iodination programme implemented in 1995 is likely to be responsible for this change.