Familial Occurrence of Nonmedullary Thyroid Cancer: A Population-based Study of 5673 First-Degree Relatives of Thyroid Cancer Patients from Norway1
- Department of Pathology, The Gade Institute, University of Bergen, N-5021 Bergen (L. F., L. A. A.) and The Cancer Registry of Norway, Montebello, Oslo (E. G.), Norway
Abstract
The purpose of this study was to estimate the occurrence of familial nonmedullary thyroid cancer (FNMTC) in a large population-based study. Of the 5274 cases of thyroid cancer on record in the Norwegian Cancer Registry between 1960 and 1995, a total of 1025 patients could be identified with verified thyroid cancer, a unique personal identification number, and a link to at least one parent. For patients with nonmedullary carcinoma, 5457 first-degree relatives in 970 families were found, compared with 216 first-degree relatives in 37 families for the medullary cancers. A standardized incidence ratio (SIR) was calculated among the relatives based on rates from the Cancer Registry of Norway. A significantly increased risk of thyroid cancer was found among the 5457 relatives of nonmedullary index cases, both for males [SIR, 5.2; confidence interval (CI), 2.1–10.7; 7 cases] and females (SIR, 4.9; CI, 3.0–7.7; 19 cases). All of these 26 thyroid cancer cases were of the nonmedullary type. Furthermore, an increased risk was found among 4282 relatives of papillary index cases, for both males (SIR, 5.8; CI, 2.1–12.6; 6 cases) and females (SIR, 4.0; CI, 2.1–7.1; 12 cases). The 36 familial papillary thyroid cancer patients had an average age at diagnosis of 43 years. Genetic influence is probably only modest for the familial nonmedullary cases and clearly weaker than for the classic familial type of medullary thyroid cancer.
Footnotes
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The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵1 This study was supported by The Norwegian Cancer Society, Grant No. D/97145/002.
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↵2 Present address: Surgical Department, National Hospital, University of Oslo, Oslo, Norway.
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↵3 To whom requests for reprints should be addressed, at Department of Pathology, The Gade Institute, Haukeland University Hospital, N-5021 Bergen, Norway. Phone: 47-55973182 and 47-55973173; Fax: 47-55973158; E-mail: Lars.Akslen{at}gades.uib.no
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↵4 The abbreviations used are: FAP, familial adenomatous polyposis; FNMTC, familial nonmedullary thyroid cancer; SIR, standardized incidence ratio; CI, confidence interval.
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- Accepted December 11, 1900.
- Received May 10, 1900.
- Revision received November 16, 1900.
