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A BRAF gene mutation is common in papillary thyroid cancer, and is associated with persistent or recurrent tumor
The background of the study. A mutation in the gene for BRAF, a component of many cells, is the most common genetic change in papillary cancer of the thyroid. This mutation leads to a change in the BRAF molecule, which in turns leads to growth and proliferation of thyroid cells. This study was done to determine the relationships between this mutation and the characteristics of thyroid cancers and the clinical characteristics and prognosis of patients with tumors with the mutation.
How the study was done. The study subjects were 347 patients with thyroid cancer. The tumor was a papillary cancer, classic subtype, in 245 patients (71 percent); a papillary cancer, follicular subtype, in 29 (8 percent); and a follicular cancer in 73 (21 percent). Treatment consisted of total or near-total thyroidectomy in 281 patients (81 percent) and a lesser thyroid resection in the remainder, and 267 (77 percent) were treated with iodine-131 (I-131). The average duration of follow-up was 72 months. DNA was extracted from tumor tissue, and the BRAF gene was analyzed.
The results of the study. The BRAF mutation was found most often in the classic papillary cancers and least often in the follicular cancers (Table).
| Table. Frequency of BRAF Mutation in 347 Thyroid Cancers. | ||
No. |
No. with BRAF Mutation |
|
| Papillary cancer, classic subtype | 245 |
126 (51%) |
| Papillary cancer, follicular subtype | 29 |
7 (24%) |
| Follicular cancer | 73 |
1 (1%) |
In the patients with both subtypes of papillary cancer, the presence of the BRAF mutation was correlated with older age, high-risk group, and recurrent or persistent cancer, but not tumor size, lymph-node invasion, or multicentric tumors.
Among patients with small cancers (
2 cm), the rate of recurrent or persistent cancer was higher in those with the BRAF mutation, as compared with those with no mutation, and the rate also was higher among the patients at low risk of tumor recurrence whose tumor had the BRAF mutation as compared with those with no mutation.
The conclusions of the study. A BRAF gene mutation is a prominent feature of the classic subtype of papillary cancer and is also present in some papillary cancers of the follicular subtype, but is rarely present in follicular cancers. In patients with papillary cancer, the presence of the mutation is associated with more extensive disease and a higher risk of recurrent or persistent cancer.
The original article. Kebebew E, Weng J, Bauer J, Ranvier G, Clark OH, Duh QY, Shibru D, Bastian B, Griffin A. The prevalence and prognostic value of BRAF mutation in thyroid cancer. Ann Surg 2007;246:466-71.
 Next Article: Patients with the tall-cell subtype of papillary cancer of the thyroid are more likely to have a recurrence than patients with the classic subtype |
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| Thyroid Digest Index | | | November 2007 Thyroid Digest |
