| Wartofsky et al., Washington, DC, USA, evaluated the clinical utility of rhTSH-stimulated thyroglobulin testing without a thyroid scan in the follow-up of patients with differentiated thyroid carcinoma. In this multicenter study patients were included who completed primary therapy consisting of near-total or total thyroidectomy and remnant ablation between 1 and 10 years prior to enrolment and receiving thyroid hormone suppression therapy with a TSH level of <0.5 mU/ml and a Tg level < 5 ng/ml. The still ongoing study is aimed to include a total of 500 patients. The interim data were as follows: of 118 patients (mean age 47.7 years) 64% had papillary, 13% folli cular, 20% papillary/follicular, and 3% Hürtle cell carcinoma. After rhTSH 14% had elevations in Tg of at least 2 ng/ml. Although no further data are present, the authors conclude that rhTSH- stimulated Tg testing may be useful in the follow-up of such patients, but further data are required to definitely define clinical utility. (Comment: Indeed this is a very preliminary study in that for instance no information is available how these results compare to Tg response after "classical" T4 withdrawal.) Also Lippi et al., Pisa, Italy, studied the usefulness of rhTSH stimulation in 40 patients after total thyroidectomy and 131-I ablation for differentiated thyroid carcinoma. All patients had undetectable serum Tg on T4 TSH suppressive therapy. Results of rhTSH administration were compared with serum Tg levels two months after T4 withdrawal. In 20/40 patients Tg became detectable after rhTSH with a peak value 3 days after injection. Metastases were detected in all these patients. Serum Tg became also detectable after T4 withdrawal in the same patients and levels were usually higher than after rhTSH. Similarly, serum Tg remained undetectable in the other 20 patients in whom serum Tg was also negative after rhTSH. (Comment: The number of patients studied is limited but if these results are confirmed in more patients, T4 withdrawal in the followup of patients treated for differentiated thyroid carcinoma may be replaced by rhTSH stimulation.) Collins et al., Chicago, IL, USA and Naples and Catanzaro, Italy, investigated RET-PTC rearrangements in 30 patients with papillary thyroid carcinoma who received neck radiation treatment during childhood and in 34 patients with papillary thyroid carcinoma without a radiation history. They found in 86.7% of the irradiated group RET rearrangement versus 52.9% in the non-irradiated group (p = 0.006). The authors conclude that although RET rearrangement is not restricted to tumors from irradiated patients, the increased prevalence supports the strong association with radiation exposure. Fatemi et al., Cantara St. Panorama City and Santa Monica, CA, USA , tested the changes of TgAb in 27 patients with differentiated thyroid carcinoma over a median period of 5.6 years. They found that in 12 patients TgAb became negative who were judged to be disease free. Seven patients, in whom metastases persisted, maintained constant TgAb levels whereas in 7 other patients with progressive metastases TgAb levels increased. The authors conclude that persistent loss of TgAb is consistent with the disease free state if serum Tg is also undetectable. In general they find that serum TgAb patterns appear to reflect changes in circulating Tg antigen and can serve as a tumor marker in patients with differentiated thyroid carcinoma. Furthermore, they found that an increase in TgAb following radioactive iodine treatment is a common phenomenon and may be a marker of therapeutic benefit. (Comment: These findings are interesting and readily explainable on the basis of the notion that TgAb disappears from the circulation when the antigen Tg becomes negative.) Park et al., Seoul, Korea, did a similar study in a total of 147 consecutive patients with differentiated thyroid carcinoma. Among the different groups that they discerned there were two groups of patients with TgAb, one without detectable Tg and another with detectable Tg. They found that in both groups persistently elevated TgAb after total thyroid ablation indeed might point to recurrent carcinoma. These authors recommend routine TgAb measurement especially in patients with a low Tg level after total thyroid ablation. Hamilton et al., Seattle, Washington, USA, compared sensitivity of carcinoma detection using physical examination combined with ultrasound in 3,430 subjects of the Hanford Thyroid Disease Study. Fine needle aspiration biopsy was offered to persons with palpable thyroid nodules or with non-palpable nodules with a diameter of at least 1.5 cm. A total of 243 patients had palpable nodules. Of the remaining 3,187 subjects without a palpable nodule, 1,165 had 1 or more nodule on ultrasound including 27 subjects with a total of 30 nodules with a diameter =1.5 cm. Adequate aspiration was obtained in 19/27 subjects revealing benign nodules in 18/19. From these and other data the authors conclude that, while ultrasound is clearly more sensitive in detecting anatomical abnormalities than physical examination, their results suggest that the use of ultrasound as a routine procedure is unlikely to yield a large number of cancers not detected by careful palpation. (Comment: These results are very welcome to me, as routine ultrasound examination of the thyroid is increasingly performed and leads to increased risks of morbidity (fine needle aspiration) and certainly increased medical costs without substantial benefit. Routine thyroid ultrasound scanning in patients without palpable abnormalities of the thyroid should be discouraged. On the other hand, in a recent report by Marqusee et al., Annals of Internal Medicine 133, 696, 2000, it is shown that the yield of detection of carcinoma, in subjects referred to a thyroid clinic because of suspected nodules, is increased using ultrasound scanning.) Ceccarelli et al., Pisa, Italy, performed whole body scanning in 315 patients after total thyroid ablation for thyroid carcinoma and showing undetectable Tg after discontinuation of TSH-suppressive T4 treatment. In all those patients whole body scanning was negative for metastatic disease, but in 120 some uptake was present in the thyroid bed that was subsequently treated with another 131-I dose. Of those patients 99.4% showed complete disappearance of thyroid bed uptake. The authors conclude that control whole body scanning is unnecessary in patients who have undetectable Tg off T4 therapy. (Comment: These results are very useful and not unexpected as it is accepted that in general serum Tg is sensitive and specific in the detection of residual/recurrent differentiated thyroid carcinoma.) Sasou et al., Morioka, Japan, confirmed that in papillary thyroid carcinoma very often multifoci are present in the thyroid. They examined total thyroids removed in 239 patients with papillary thyroid carcinoma. Multifoci were found in 61.1%: in the same lobe 23.0%, opposite lobe 13.0%, and both lobes 25.1%. (Comment: These findings are not new and show again that multifocity is present in the majority of thyroids harboring papillary carcinoma. Another matter, however, is to what extent these multifoci will become biologically active if left in situ. However, the general opinion is that (near) total thyroidectomy, certainly in nodules with diameter >1cm, is the first treatment option in papillary thyroid carcinoma.) Lee et al., Seoul, Korea, tested the utility of preoperatively FDG-PET scanning in 22 patients with 131-I scan negative papillary thyroid carcinoma. In 85 cervical lymph node groups dissected, 56 lymph node groups revealed metastases on histological examination. The sensitivity and specificity of FDG-PET to detect these metastases was 80% and 83% respectively. The authors conclude that in patients with 131-I negative scans preoperative FDG-PET scanning is useful in detection of lymph node metastases. Nilsson et al., Göteborg and Sahlgrenska, Sweden, studied the mechanism of stunning (inhibition of iodine uptake by thyroid tissue after diagnostic 131-I whole body scanning in patients treated for differentiated thyroid carcinoma) in pig thyrocytes in primary culture. They found that iodine uptake immediately after 131-I exposure was not inhibited but was decreased after 3 days. The inhibition was counteracted by perchlorate or lack of TSH-stimulation during 131-I exposure. Their results indicate that the stunning effect is caused selective inhibition of iodide transporting mechanisms. Moncayo et al., Innsbruck, Austria, tested treatment of metastatic thyroid carcinoma with Yttrium labeled somatostatin analogs in 19 patients with known metastases (2 follicular, 7 papillary, 3 oncocytic, 4 medullary, and 3 anaplastic carcinoma) in whom 131-I whole body scanning was negative. Uptake in tumor tissue was found in 15 patients with tracer Yttrium labeled somatostatin and they were so far treated with 1-7 cycles Yttrium labeled somatostatin with doses of 925 MBq or 1,295 MBq per cycle. The preliminary results show improvement in 4 patients, stable disease in 5, and progression in 2, while 4 patients died. (Comment: Although preliminary, these results show that this therapeutic approach may be of value in patients who do not show 131-I uptake in metastatic tissue.) |
