Evidence Supports Aggressive Papillary Thyroid Ca Treatment

Multifocal tumors in papillary thyroid cancer appear to often arise as independent tumors—a finding that supports the use of bilateral thyroidectomy and radioablation of remaining tissue, according to Trisha M. Shattuck of the University of Connecticut, Farmington, and her associates.

Papillary thyroid carcinoma is the most common cancer of the thyroid gland, and it is often multifocal—typically with a “primary” tumor greater than 1 cm in diameter and additional, much smaller “microcarcinomas.”

Multifocal carcinomas have been associated with increased risks of lymph-node and distant metastases, persistent local disease after initial treatments, and regional recurrence—features that have suggested that patients be treated aggressively.

It has been unclear, however, whether multiple intrathyroid tumors are metastases of a primary tumor or whether they arise independently as individual carcinomas, the investigators said (N. Engl. J. Med. 2005;352:2406–12).

They examined tumor samples from 17 women with multifocal papillary thyroid carcinoma who underwent thyroidectomy. Using a polymerase chain reaction (PCR) assay involving the human androgen receptor gene, they analyzed tumor DNA for patterns of X-chromosome inactivation (inactivation of either the maternal or paternal X-chromosome).

Such patterns can be used to determine whether a tumor arose from one or multiple progenitor cells because the inactivated chromosome is stably transmitted from parent cell to progeny cell, the investigators explained.

Multiple tumor foci from 10 of the 17 patients were suitable for analysis; they yielded DNA of adequate quality and quantity and were heterozygous for the human androgen receptor gene polymorphism. A single X chromosome was inactivated in each focus, the investigators reported.

Tumors from 5 of the 10 patients showed discordant patterns of X-chromosome inactivation that indicated the tumors arose separately from different progenitor cells. Tumors in the other five patients showed patterns that could be interpreted as indicating either a shared or independent origin.

The findings “favor the independent clonal origins of the distinct foci in some [and possibly most] of these cases,” according to the investigators.

The findings also “imply that any thyroid tissue remaining after surgery to treat papillary thyroid cancer in patients with multifocal disease may contain—or be likely to develop—additional foci of cancer that could become recurrences.”

In an editorial, Robert D. Utiger, M.D., wrote that the evidence “supports the clinical finding that patients with papillary carcinoma who undergo thyroid lobectomy are more likely than those who undergo near total thyroidectomy to have recurrent carcinoma in the remaining lobe as well as elsewhere.”

Annual estimates of thyroid cancer diagnoses have been growing faster than the population for several decades, and the proportion of these cancers that are papillary carcinomas is growing as well, said Dr. Utiger of Harvard Medical School, Boston (N. Engl. J. Med. 2005;352:2376–8).

Multifocal tumors in papillary thyroid cancer appear to often arise as independent tumors—a finding that supports the use of bilateral thyroidectomy and radioablation of remaining tissue, according to Trisha M. Shattuck of the University of Connecticut, Farmington, and her associates.

Papillary thyroid carcinoma is the most common cancer of the thyroid gland, and it is often multifocal—typically with a “primary” tumor greater than 1 cm in diameter and additional, much smaller “microcarcinomas.”

Multifocal carcinomas have been associated with increased risks of lymph-node and distant metastases, persistent local disease after initial treatments, and regional recurrence—features that have suggested that patients be treated aggressively.

It has been unclear, however, whether multiple intrathyroid tumors are metastases of a primary tumor or whether they arise independently as individual carcinomas, the investigators said (N. Engl. J. Med. 2005;352:2406–12).

They examined tumor samples from 17 women with multifocal papillary thyroid carcinoma who underwent thyroidectomy. Using a polymerase chain reaction (PCR) assay involving the human androgen receptor gene, they analyzed tumor DNA for patterns of X-chromosome inactivation (inactivation of either the maternal or paternal X-chromosome).

Such patterns can be used to determine whether a tumor arose from one or multiple progenitor cells because the inactivated chromosome is stably transmitted from parent cell to progeny cell, the investigators explained.

Multiple tumor foci from 10 of the 17 patients were suitable for analysis; they yielded DNA of adequate quality and quantity and were heterozygous for the human androgen receptor gene polymorphism. A single X chromosome was inactivated in each focus, the investigators reported.

Tumors from 5 of the 10 patients showed discordant patterns of X-chromosome inactivation that indicated the tumors arose separately from different progenitor cells. Tumors in the other five patients showed patterns that could be interpreted as indicating either a shared or independent origin.

The findings “favor the independent clonal origins of the distinct foci in some [and possibly most] of these cases,” according to the investigators.

The findings also “imply that any thyroid tissue remaining after surgery to treat papillary thyroid cancer in patients with multifocal disease may contain—or be likely to develop—additional foci of cancer that could become recurrences.”

In an editorial, Robert D. Utiger, M.D., wrote that the evidence “supports the clinical finding that patients with papillary carcinoma who undergo thyroid lobectomy are more likely than those who undergo near total thyroidectomy to have recurrent carcinoma in the remaining lobe as well as elsewhere.”

Annual estimates of thyroid cancer diagnoses have been growing faster than the population for several decades, and the proportion of these cancers that are papillary carcinomas is growing as well, said Dr. Utiger of Harvard Medical School, Boston (N. Engl. J. Med. 2005;352:2376–8).

Multifocal tumors in papillary thyroid cancer appear to often arise as independent tumors—a finding that supports the use of bilateral thyroidectomy and radioablation of remaining tissue, according to Trisha M. Shattuck of the University of Connecticut, Farmington, and her associates.

Papillary thyroid carcinoma is the most common cancer of the thyroid gland, and it is often multifocal—typically with a “primary” tumor greater than 1 cm in diameter and additional, much smaller “microcarcinomas.”

Multifocal carcinomas have been associated with increased risks of lymph-node and distant metastases, persistent local disease after initial treatments, and regional recurrence—features that have suggested that patients be treated aggressively.

It has been unclear, however, whether multiple intrathyroid tumors are metastases of a primary tumor or whether they arise independently as individual carcinomas, the investigators said (N. Engl. J. Med. 2005;352:2406–12).

They examined tumor samples from 17 women with multifocal papillary thyroid carcinoma who underwent thyroidectomy. Using a polymerase chain reaction (PCR) assay involving the human androgen receptor gene, they analyzed tumor DNA for patterns of X-chromosome inactivation (inactivation of either the maternal or paternal X-chromosome).

Such patterns can be used to determine whether a tumor arose from one or multiple progenitor cells because the inactivated chromosome is stably transmitted from parent cell to progeny cell, the investigators explained.

Multiple tumor foci from 10 of the 17 patients were suitable for analysis; they yielded DNA of adequate quality and quantity and were heterozygous for the human androgen receptor gene polymorphism. A single X chromosome was inactivated in each focus, the investigators reported.

Tumors from 5 of the 10 patients showed discordant patterns of X-chromosome inactivation that indicated the tumors arose separately from different progenitor cells. Tumors in the other five patients showed patterns that could be interpreted as indicating either a shared or independent origin.

The findings “favor the independent clonal origins of the distinct foci in some [and possibly most] of these cases,” according to the investigators.

The findings also “imply that any thyroid tissue remaining after surgery to treat papillary thyroid cancer in patients with multifocal disease may contain—or be likely to develop—additional foci of cancer that could become recurrences.”

In an editorial, Robert D. Utiger, M.D., wrote that the evidence “supports the clinical finding that patients with papillary carcinoma who undergo thyroid lobectomy are more likely than those who undergo near total thyroidectomy to have recurrent carcinoma in the remaining lobe as well as elsewhere.”

Annual estimates of thyroid cancer diagnoses have been growing faster than the population for several decades, and the proportion of these cancers that are papillary carcinomas is growing as well, said Dr. Utiger of Harvard Medical School, Boston (N. Engl. J. Med. 2005;352:2376–8).