Devita, Hellman, and Rosenberg's Cancer

LWBK1006-25 LWW-Govindan-Review December 12, 2011 19:21

Chapter 25•Cancer of the Endocrine System 359

considered to be in this category. Other high-risk features include female

patients aged more than 50 years, incomplete excision, capsular invasion,

and tumor size more than 5 cm.

Answer 25.7. The answer is E.

This is an example of dedifferentiated papillary thyroid carcinoma, where

the cancer no longer shows uptake of iodine but can be detected on PET

scan. Another caveat in this case is the recognition of recommended long-

term follow-up, perhaps indefinitely. In thyroid carcinoma, TG level is

very sensitive, particularly when TSH is suppressed, and this is also true in

dedifferentiated thyroid carcinoma. Chemotherapy has been disappoint-

ing in this disease. Surgical resection, and perhaps external beam radia-

tion, is his best option to achieve local control and relief of symptoms.

Answer 25.8. The answer is D.

RET/PTC rearrangements are found in about 20% of papillary thyroid

carcinoma in general, and in 60% to 80% of those occurring after irra-

diation. BRAF mutation can be found in patients with papillary thyroid

carcinoma, but it is not associated with radiation exposure. APC gene

mutation is found in patients with familial adenomatous polyposis, and

some of these patients might develop differentiated thyroid carcinoma.

RET proto-oncogene mutations are associated with MEN2.

Answer 25.9. The answer is D.

All of the listed features indicate poor prognosis. Additional poor prog-

nostic features include women aged more than 50 years and the presence

of distant metastasis. These features can be remembered by the acronym

AMES (age, metastasis, extracapsular invasion, size).

Answer 25.10. The answer is B.

This case highlights the importance of the fact that IV contrast with diag-

nostic CT scan interferes with the thyroid cancer uptake of iodine during

radioactive iodine scan. This test should be done at least 6 to 8 weeks

after iodine-contrast CT scan to allow the excretion of the circulating

iodine pool; 24-hour urinary iodine can be measured before repeat iodine

scanning in these cases.

Answer 25.11. The answer is D.

MTC arises from the parafollicular C cells in the thyroid gland and is

not associated with radiation exposure. RET proto-oncogene testing is

indicated even in the absence of family history. Pheochromocytoma must

be ruled out before any surgical resection by measuring metanephrine

levels.

Answer 25.12. The answer is C.

Anaplastic thyroid carcinoma remains an incurable cancer. It grows

rapidly, and 20% to 50% of cases are associated with distant metastasis.