Second primary malignancies following thyroid cancer: a population-based study in Taiwan.
OBJECTIVE
Most studies on second primary malignancies (SPMs) after primary thyroid cancer were conducted in USA or Europe. The discrepancy between SPMs in these studies could be attributed to geographical and ethnic heterogeneity. Thus, there is a clear need for another large-scale epidemiological study, particularly in Asian countries, to define the incidence and risk of SPMs in thyroid cancer survivors.


METHODS
A population-based study was conducted using the nation-wide database from Taiwan Cancer Registry between 1979 and 2006.


METHODS
We quantified standardized incidence ratios (SIRs) and cumulative incidence of SPMs among 19,068 individuals (4205 males and 14,863 females) with primary thyroid cancer.


RESULTS
A total of 644 cases (3.38%) developed at least a SPM during 134,678 person-years of follow-up. The risk for subsequent SPMs was significantly greater than that of the general population (SIR=1.33, 95% CI 1.23-1.44). There was a greater risk of developing major salivary glands, nasopharyngeal, lung, thymus, breast (females), bladder, and brain cancers, and leukemia and lymphoma. We observed that the risk was highest within the first 5 years of diagnosis of thyroid cancer (SIR=5.29, 1.68, and 0.68 for ≤ 5, 5-10, and >10 respectively) and in the younger patients (SIR=1.81 vs 1.61 for <50 and ≥ 50 respectively). The median overall survival for primary thyroid cancer patients was 23.28 years, but it was only 4.73 years for those who developed SPMs.


CONCLUSIONS
Thyroid cancer is associated with a 33% risk increment of SPMs, which had a negative impact on survival. There are sites of SPMs in the Asian population that are distinctive from those in the Western population, suggesting that other genetic predisposition or environmental factors may play a role.
Department of Hematology and Oncology, Chang-Gung Memorial Hospital, No. 6, Chia-Pu Road, Putz City, Chia-Yi, Taiwan.
Chang-Hsien
CH
Lu
Kuan-Der
KD
Lee
Ping-Tsung
PT
Chen
Chih-Cheng
CC
Chen
Feng-Che
FC
Kuan
Cih-En
CE
Huang
Miao-Fen
MF
Chen
Min-Chi
MC
Chen
D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000453:epidemiology* / Q000473:pathology*; D012042:Registries; D012306:Risk; D012737:Sex Factors; D013534:Survival; D013624:Taiwan / Q000453:epidemiology; D013964:Thyroid Neoplasms / Q000453:epidemiology* / Q000473:pathology*