Natural history, predictive factors of apparent disease (structural or biochemical) and spontaneous excellent response in patients with papillary thyroid carcinoma and indeterminate response to initial therapy with radioiodine

BACKGROUND

About 20% of patients with papillary thyroid carcinoma (PTC) submitted to total thyroidectomy followed by radioactive iodine (RAI) exhibit an indeterminate response to therapy. The aim was to evaluate the natural history, predictive factors of apparent disease (structural or biochemical), and spontaneous excellent response in patients with PTC and an initial indeterminate response to RAI therapy defined based on unstimulated Tg (u-Tg).

METHODS

We evaluated 164 patients who were initially treated with total thyroidectomy and RAI and who had an indeterminate response to therapy (u-Tg between 0.2 and 1 ng/ml, undetectable anti-Tg antibodies [TgAb], and neck ultrasonography [US] without anomalies). None of the patients received empirical therapy with RAI. The patients were followed up for 24 to 144 months (median 72 months).

RESULTS

Apparent disease occurred in 16 patients (9.7%), including 13 with structural disease and 3 with u-Tg elevation > 1 ng/ml, but no tumor was detected by the imaging methods (biochemical disease). A higher frequency of disease was observed in patients with >3 lymph node metastases (LNM) and initial u-Tg >0.35 ng/ml. The frequency was only 2% among patients with ≤3 LNM and u-Tg ≤0.35 ng/ml and 9.7% among patients with > 3 LNM or u-Tg >0.35 ng/ml, while the frequency was 27% in patients with >3 LNM and u-Tg >0.35 ng/ml. In the absence of any additional therapy, u-Tg was <0.2 ng/ml (excellent response) in the last assessment in 70 patients (42.7%). Only initial u-Tg was associated with a higher probability of spontaneously achieving an excellent response: 40/72 patients (55.5%) with u-Tg ≤0.35 ng/ml versus 30/92 patients (32.6%) with u-Tg >0.35 ng/ml.

CONCLUSIONS

A minority of patients with PTC and an initial indeterminate response to RAI defined based on u-Tg develop apparent disease (structural or biochemical) and many spontaneously achieve an excellent response. The risk of disease can be refined based on parameters such as the extent of lymph node involvement and initial Tg concentration.

Diagnostic Utility of Procalcitonin for Sporadic Medullary Thyroid Carcinoma in Patients with Nodular Disease and Mild or Moderate Hypercalcitoninemia

Many authors recommend the measurement of serum calcitonin (Ctn) to screen for sporadic medullary thyroid carcinoma (MTC) in patients with thyroid nodules. In this situation, procalcitonin (pro-Ctn) would have greater utility in patients with hypercalcitoninemia<100 pg/ml. The aim of this study was to evaluate the utility of pro-Ctn in patients with thyroid nodules and without a suspicion of familial MTC or type 2 multiple endocrine neoplasia who had mild or moderate hypercalcitoninemia without an apparent cause. Consecutive patients with nodular thyroid disease assessed routinely by Ctn measurement were selected. Sixty patients with basal Ctn>10 pg/ml but<100 pg/ml were included. Nine patients (15%) had MTC, with cytology being diagnostic in only four. Among the 51 patients without MTC, pro-Ctn was<0.1 ng/ml in 46 (90.2%). All patients with MTC had pro-Ctn>0.1 ng/ml. Basal Ctn was>24.6 pg/ml in all patients with MTC and in 42 patients (82.3%) without MTC. It is noteworthy that among patients with basal Ctn>24.6 pg/ml (n=18) pro-Ctn>0.1 ng/ml identified all patients with MTC and 64.2% of subjects with these pro-Ctn concentrations had this tumor. In conclusion, we did not find superiority of pro-Ctn over Ctn for the diagnosis of sporadic MTC in patients with nodular disease and mild or moderate hypercalcitoninemia. However, in the case of patients with hypercalcitoninemia in the gray zone, pro-Ctn has an excellent negative predictive value while the data regarding its positive predictive value are not uniform.

Development and validation of an instrument (CSII - Brazil) to assess users' conceptual and procedural knowledge of continuous subcutaneous infusion systems

OBJECTIVE

To develop, adapt and validate an instrument named "CSII - Brazil" to assess users' conceptual and procedural knowledge of continuous subcutaneous insulin infusion systems.

METHODS

Methodological and exploratory study developed in three stages: a) instrument development; b) content validation and cultural adaptation (evaluation by a committee of experts and pre-test with CSII users); c) psychometric validation through instrument application in a sample of 60 patients by means of the web tool e-Surv. Internal consistency and reproducibility analyses were performed within IBM SPSS Statistics 20 programming environment.

RESULTS

The 16 multiple-choice question instrument successfully attained a content validity index of 0.97, showing satisfactory internal consistency, with 0.61 Cronbach's alpha [95% CI 0.462-0.746] and an intraclass correlation coefficient of 0.869 [95% CI: 0.789-0.919] between the test and retest scores.

CONCLUSION

The CSII - Brazil instrument is considered adequate and validated to assess continuous subcutaneous infusion system users' conceptual and procedural knowledge.

Hurthle Cells Adenoma With Distant Metastases Refractory to Radioiodine

Introduction: Adenoma of the thyroid is defined as an encapsulated follicular tumor that is well delimited in relation to the adjacent parenchyma and whose cells do not exhibit the nuclear alterations of papillary thyroid carcinoma (PTC), and in the absence of capsular and vascular invasion. Adenoma, including the of Hurthle cells, is considered a benign tumor. No additional treatment is recommended after resection of the tumor. Case: A 64-year-old man was submitted to total thyroidectomy because of a nodule measuring 3.5 cm with indeterminate cytology (predominance of Hurthle cells). Histology revealed an Hurthle cells adenoma of 3.2 cm. The tumor did not exhibit vascular or capsular invasion, the cells did not contain nuclei of PTC, and no necrosis or mitoses were observed. Five years after surgery, serum thyroglobulin (Tg) was elevated (25 ng/ml) during euthyroidism (TSH 0.6 mUI/l) and in the absence of anti-Tg antibodies. Serum calcitonin was undetectable. The patient developed a progressive increase in Tg and neck ultrasonography (US), chest computed tomography (CT), and FDG-PET/CT were performed. US revealed atypical lymph nodes (the largest with 12 mm) and cytology showed abundance of Hurthle cells. Chest CT detected multiple nodules, the largest measuring 15 mm, and FDG-PET/CT revealed areas of cervical and pulmonary uptake corresponding to the lesions seen on US and CT. The patient received 100 mCi radioactive iodine and post-therapy whole-body scanning showed mild uptake only in the thyroid bed. The patient continues to show progressive increase in Tg (last measurement > 1,000 ng/ml), as well as progression of metastases. He remains under follow-up and on therapy with tyrosine kinase inhibitor. The histology result was revised by two pathologists with broad experience in thyroid pathology who confirmed the initial findings compatible with adenoma. Conclusion: The present case shows that, although rare, Huthle cells tumors can develop metastases even when the tumor is < 4 cm and unequivocally without nuclei of PTC or capsular and vascular invasion, thus considered benign (adenoma). As observed in this case, these metastases can be macrometastases, distant, and refractory to radioiodine. Reference: Lloyd RV, Osamura RY, Klöppel G, Rosai J, ed. WHO Classification of Tumours of Endocrine Organs. 4^th edition Lyon: IARC; 2017

Pregnancy During Active Surveillance of Papillary Thyroid Microcarcinoma

Introduction: Most patients diagnosed with papillary thyroid microcarcinoma (microPTC) classified as low risk and therefore eligible for active surveillance (AS) are women. Although age is a predictor of tumor progression (more frequent among young people), young adults are “appropriate” candidates for AS. Consequently, a proportion of patients with low-risk microPTC eligible for AS are women of childbearing age and knowledge of the effect of pregnancy on tumor progression is therefore important. In the Japanese population, Ito et al. observed this progression in only 8% of pregnancies. None of the series on the outcomes of AS in western populations has so far reported the behavior of microPTC in women who became pregnant during AS. Methods: We have submitted patients with low-risk microPTC to AS. Our management has been not to interrupt AS, i.e., not to indicate surgery when the patient wishes to become pregnant. We report here the results of five patients who became pregnant during AS and their follow-up up to 6 months after delivery. Results: The patients were 26 to 36 years old (median 29 years) when they became pregnant. None of them had a history of radiation exposure, one had a family history of PTC, one had associated Hashimoto’s thyroiditis, and all of them had only one tumor focus and were considered “appropriate” (but not “ideal”) candidates for AS. In fact, when pregnancy was diagnosed, the patients continued to exhibit the criterion for AS according to our initial protocol (tumor ≤ 1.2 cm, no apparent lymph node metastases [LNM] or extrathyroidal extension [ETE] on ultrasonography [US]). All women were monitored by monthly measurement of TSH and levothyroxine (L-T4) was administered during pregnancy to maintain TSH between 0.1 and 1 mIU/L. US was performed when pregnancy was diagnosed (between 6 and 9 weeks of gestation), around 22 weeks, at the end of pregnancy, and 6 months after delivery. During the evaluations, none of the patients had apparent LNM or ETE on US. None of the patients exhibited tumor growth, defined as an increase in diameter ≥ 3 mm. Tumor growth ≥ 50% was observed in only one patient, with a small reduction after delivery. Conclusions: Our preliminary results suggest that pregnancy is not associated with a high risk of progression of low-risk microPTC and that the desire to get pregnant or pregnancy should not be an exclusion factor for AS. References: Effects of Pregnancy on Papillary Microcarcinomas of the Thyroid Re-Evaluated in the Entire Patient Series at Kuma Hospital. Ito Y, Miyauchi A, Kudo T et al. Thyroid 2016; 26:156-60 AND Active Surveillance in Adults with Low-Risk Papillary Thyroid Microcarcinomas: A Prospective Study. Rosario PW, Mourão GF, Calsolari MR. Horm Metab Res. 2019; 51:703-8.

Noninvasive Encapsulated Papillary RAS-Like Thyroid Tumor (NEPRAS)

Introduction: The diagnosis of thyroid tumors arising from follicular cells that are encapsulated/well delimited and noninvasive is a challenge. When unequivocal nuclear alterations are present, the final diagnosis can range from noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) and classical/encapsulated papillary thyroid cancer (PTC), including aggressive subtypes, to poorly differentiated carcinoma. As proposed recently, the presence of papillae in the absence of exuberant nuclear alterations (nuclear score 2), given that the other criteria for NIFTP are met, may not be sufficient for the diagnosis of PTC. This condition is called “noninvasive encapsulated papillary RAS-like thyroid tumor” (NEPRAS), whose nature would be borderline and not malignant. Revising our cases of tumors &gt; 1 cm that were diagnosed previously as PTC and that were encapsulated/well delimited and noninvasive, we found three cases of NEPRAS. We now revised our cases of tumors &gt; 1 cm diagnosed previously as well-differentiated tumor of uncertain malignant potential (WDT-UMP) because the nuclear alterations were not considered to be sufficient for the diagnosis of PTC on that occasion. Case: In a 29-year-old euthyroid male patient with a single thyroid nodule whose fine-needle aspiration had revealed indeterminate cytology, a single tumor measuring 3.2 cm was reclassified from WDT-UMP to NEPRAS. For this diagnosis, the tumor met the following criteria: encapsulation or clear demarcation, no vascular or capsular invasion, presence of papillae, &lt; 30% solid/trabecular/insular growth pattern, no tumor necrosis or high mitotic activity, and nuclear score 2. The BRAFV600E mutation was absent. The patient continues to show no signs of recurrence 7 years after lobectomy. Conclusion: Despite the presence of papillae, some tumors may be reclassified from malignant (encapsulated PTC) to borderline (NEPRAS). This proposal would result in a change of management, with the same implications as those seen for the change from noninvasive encapsulated follicular variant of PTC to NIFTP. References: Ohba K et al. Encapsulated Papillary Thyroid Tumor with Delicate Nuclear Changes and a KRAS Mutation as a Possible Novel Subtype of Borderline Tumor. J Pathol Transl Med. 2019;53:136-41 AND Rosario PW. Noninvasive encapsulated papillary RAS-like thyroid tumor (NEPRAS) or encapsulated papillary thyroid carcinoma (PTC). J Pathol Transl Med. 2020;54:263-4.

Follow-up of patients with thyroid cancer and antithyroglobulin antibodies: a review for clinicians

Antithyroglobulin antibodies (TgAb) are present in up to 25% of patients with differentiated thyroid carcinoma on initial postoperative assessment. Detectable concentrations of TgAb even below the manufacturer's cut-off can interfere with serum thyroglobulin (Tg) determination. When Tg is quantified using an immunometric assay (IMA) (hereafter referred to as Tg-IMA), this interference results in underestimated values of Tg. Although promising, more clinical trials evaluating the capacity of liquid chromatography/tandem mass spectrometry and of new assays to detect elevated Tg in patients with TgAb and structural disease are necessary, particularly when Tg is undetectable by a second-generation IMA (Tg-2GIMA). Neck ultrasonography (US) should be performed in patients submitted to total thyroidectomy and with negative Tg-IMA but with detectable TgAb more than 6 months after initial therapy. In patients treated with 131I, comparison of TgAb concentrations obtained before this treatment is useful to estimate the risk of disease and to guide the investigation. If initial assessment does not reveal any persistent tumor, the repetition of US is recommended while TgAb persist. Significant elevation of TgAb requires extended investigation. On the other hand, patients with negative Tg-IMA and US without abnormalities who exhibit a reduction > 50% in TgAb generally do not require investigation. Although TgAb can interfere with Tg, the management and follow-up of patients submitted to total thyroidectomy with borderline TgAb can probably be the same as those recommended for patients without TgAb if Tg-2GIMA and US indicate an excellent response to therapy. Currently, the presence/absence or the trend of TgAb levels cannot be considered in the follow-up of patients submitted to lobectomy.

Usefulness of accessible imaging methods in thyroid nodules with indeterminate cytology

In thyroid nodules (TN) submitted to fine-needle aspiration (FNA), Bethesda categories III and IV are considered 'indeterminate' cytology. This result corresponds to 10-25% of all FNAs and the risk of malignancy (RoM) ranges from 10% to 30% for category III and from 15% to 40% for category IV. This review analyzed the practical applicability of accessible imaging method in the management of patients with cytologically indeterminate TN > 1 cm (ITN). When ITN are highly suspicious on ultrasonography (US), the RoM supports surgical indication even in the absence of additional tests. The same can be applied to ITN of intermediate suspicion but with elevated stiffness on elastography. Follow-up without additional tests is acceptable in the case of ITN with low-risk cytology and low-suspicion appearance on US and elastography (if obtained). In the case of ITN without highly suspicious US appearance, 123I scintigraphy may be obtained in patients with TSH < 1-1.5 mIU/L to rule out hyperfunctioning nodules before requesting diagnostic methods that are more expensive and less accessible. In addition, in ITN with not very suspicious US appearance, 18FDG-PET may be obtained. If this method does not reveal nodular uptake, the risk of the nodule corresponding to a macrocarcinoma is sufficiently low in order to allow follow-up. The positive predictive value of focal nodular uptake on 18FDG-PET depends on the pre-test RoM, cytological findings, and maximum SUV. There is currently no evidence for the use of CT, MRI or imaging using 99mTc-MIBI to define the nature of ITN.

Can patients with papillary thyroid carcinoma and low postoperative thyroglobulin in the presence of clinically apparent lymph node metastases (cN1) be spared from radioiodine?

BACKGROUND

The study evaluated the recurrence rate in patients with papillary thyroid carcinoma (PTC) and clinically apparent lymph node metastases (LNM) (cN1) who had low thyroglobulin (Tg) after total thyroidectomy and who were not submitted to adjuvant therapy with ¹³¹I.

METHODS

This was a prospective study. It included 82 cN1 patients (≤3 LNM ≤1.5 cm without macroscopic extracapsular extension) with tumors ≤4 cm without macroscopic extrathyroid invasion (T1-2) and who after thyroidectomy had unstimulated Tg (u-Tg) < 0.3 ng/ml, negative antithyroglobulin antibodies (TgAb), and neck ultrasonography (US) showing no anomalies. The patients were not submitted to therapy with ¹³¹I.

RESULTS

The time of follow-up ranged from 24 to 156 months (median 84 months). Seventy-nine patients (96.3%) continued to have u-Tg < 0.3 ng/ml and negative US. Three patients (3.6%) exhibited an increase in Tg and structural recurrence was detected in two. After treatment, these patients achieved u-Tg < 1 ng/ml and the imaging methods revealed no apparent tumor.

CONCLUSIONS

The results suggest that even cN1 patients, given the absence of extensive LNM or other adverse findings, who have low Tg and neck US showing no anomalies after thyroidectomy do not require radioiodine.

Role of adjuvant therapy with radioactive iodine in patients with elevated serum thyroglobulin after neck reoperation due to recurrent papillary thyroid cancer: a monoinstitutional comparative study

BACKGROUND

Most patients with papillary thyroid cancer (PTC) and lymph node metastases (LNM) undergoing reoperation do not show apparent disease after this procedure, but serum thyroglobulin (Tg) continues to be elevated in part of them. This study evaluated adjuvant therapy with ¹³¹I in these patients.

METHODS

Patients with PTC and LNM diagnosed after initial therapy were selected. Patients undergoing reoperation and those without apparent disease after this procedure, but with nonstimulated Tg ≥1 ng/ml 6 months after reoperation, were included. The first 25 patients were submitted to therapy with ¹³¹I (groups A) and the subsequent 30 patients did not receive this therapy (group B).

RESULTS

Groups A and B were similar. During further follow-up, 21 patients developed structural disease and 34 continued without detectable disease (eight achieved complete remission). The outcomes were similar in groups A and B. Patients with Tg reduction >50% after reoperation tended to have a lower risk of recurrence (22.7 versus 48.5%), notably distant metastases (0 versus 15.1%), and were more likely to achieve complete remission (28 versus 3%). Patients with LNM FDG-positive had a higher risk of recurrence (54.5 versus 11.7%) and were less likely to achieve complete remission (3 versus 29.4%) after reoperation.

CONCLUSION

Our results suggest that therapy with ¹³¹I apparently does not prevent recurrences among patients who continue to have elevated Tg after neck reoperation. Further studies involving these patients are necessary, especially those who are at high risk of recurrence.

Usefulness of Serum Calcitonin in Patients with Thyroid Nodules ≤ 1 cm Without an Indication for Fine-Needle Aspiration

Fine-needle aspiration (FNA) is not necessary in adults with nodules ≤ 1 cm without apparent extrathyroidal extension (ETE) or lymph node (LN) involvement on ultrasonography (US). In the absence of FNA and serum calcitonin (Ctn) measurement, medullary thyroid microcarcinomas (microMTC) are not diagnosed. The aim of this prospective study was to evaluate Ctn levels in adults with a low clinical risk of MTC and nodules ≤ 1 cm without ETE or LN involvement on US. A total of 506 consecutively seen adults who had nodules with two or more suspicious features were included. Patients with elevated basal Ctn underwent a calcium stimulation test and FNA. Basal Ctn was normal in 490 patients (96.8%). In the 16 patients with elevated basal Ctn, FNA revealed MTC in only one patient and MTC was not suspected in the 15 patients with elevated basal Ctn. Three patients with stimulated Ctn<100 pg/ml and benign cytology were not submitted to surgery. MTC was excluded by histology in three patients with stimulated Ctn<100 pg/ml and indeterminate or suspicious cytology and in eight patients with stimulated Ctn>100 pg/ml. One patient with stimulated Ctn>100 pg/ml had MTC. Ctn was undetectable 6 months after surgery in two patients with MTC. Although uncommon, even subjects without a suspicious history and with nodules ≤ 1 cm without ETE or LN involvement on US, but with suspicious findings, can have microMTC. The measurement of Ctn permits the diagnosis of these cases.

Active Surveillance in Adults with Low-Risk Papillary Thyroid Microcarcinomas: A Prospective Study

The acceptance and results of active surveillance in patients with low-risk papillary thyroid microcarcinomas (PTMC) are unknown in populations other than the Japanese population. This was the objective of the present prospective study. We selected patients ≥20 years who had thyroid nodules ≤1.2 cm with intermediate or high suspicion for malignancy on ultrasonography (US), not located near the recurrent laryngeal nerve and without extrathyroidal invasion or apparent lymph node metastases, whose cytology was suspicious (Bethesda V) or diagnostic (Bethesda VI) of papillary thyroid carcinoma. Patients who opted for active surveillance were followed up by biannual US. Fifteen patients (18.7%) readily opted for surgery and 12 (15%) for active surveillance. Fifty-three patients (66.2%) delegated the decision or wished to know the doctor's preference before deciding. After the doctor had declared his/her preference for active surveillance, 50 patients decided to have this management and three to have surgery. Only 1/70 patients exhibited tumor progression (growth associated with a suspicion of extrathyroidal invasion) after 30 months of follow-up. Two patients decided to have surgery during follow-up, although the indication was not defined by the study. A>50% reduction in tumor volume was observed in three patients. The study shows that active surveillance can be well accepted if doctors were convinced that it is the best option for patients with low-risk PTMC. At least the short-term results reproduced those observed in other populations, with tumor progression being uncommon.

Definition of the Response to Initial Therapy with Radioiodine in Patients with Differentiated Thyroid Carcinoma: Basal or Stimulated Thyroglobulin?

Basal thyroglobulin (b-Tg) measured with second-generation assay or stimulated Tg (s-Tg) can be used to define the response to therapy of differentiated thyroid carcinoma. However, they do not always define the same category and guidelines do not establish "if" or "when" s-Tg needs to be obtained. We studied 304 patients without clinically apparent disease or disease detected by neck ultrasonography and without anti-Tg antibodies 9-12 months after therapy. Based on b-Tg, 196 patients had an excellent response and 108 had an indeterminate response. Based on s-Tg, a change in category occurred in 10.2% of the patients with an initial excellent response (all to indeterminate response) and in half the patients with an initial indeterminate response (44.4% to excellent response and 5.5% to biochemical incomplete response). One case of recurrence was observed among patients with an initial excellent response but whose response changed to indeterminate after s-Tg, while no disease was detected among those who remained in the initial category; however, this difference was not significant. In patients with an initial indeterminate response, no recurrence was detected among those whose response changed to excellent after s-Tg, while 11.1 and 33.3% of those who remained in the initial category or whose response changed to biochemical incomplete, respectively, had structural disease. This study suggest that, in low- or intermediate-risk patients, s-Tg better defines the response to therapy with ¹³¹I when it is classified as indeterminate based on b-Tg using second-generation assay. However, s-Tg is not necessary when b-Tg defines the response as excellent.

Thyroid nodules ≤ 1 cm and papillary thyroid microcarcinomas: Brazilian experts opinion

The indolent evolution of low-risk papillary thyroid microcarcinoma (mPTC) in adult patients and the consequences of thyroidectomy require a revision of the management traditionally recommended. Aiming to spare patients unnecessary procedures and therapies and to optimize the health system in Brazil, we suggest some measures. Fine-needle aspiration of nodules ≤ 1 cm without extrathyroidal extension on ultrasonography should be performed only in nodules classified as "very suspicious" (i.e., high suspicion according to ATA, high risk according to AACE, TI-RADS 5) and in selected cases [age < 40 years, nodule adjacent to the trachea or recurrent laryngeal nerve (RLN), multiple suspicious nodules, presence of hypercalcitoninemia or suspicious lymph nodes]. Active surveillance (AS) rather than immediate surgery should be considered in adult patients with low-risk mPTC. Lobectomy is the best option in patients with unifocal low-risk mPTC who are not candidates for AS because of age, proximity of the tumor to the trachea or RLN, or because they opted for surgery. The same applies to patients who started AS but had a subsequent surgical indication not due to a suspicion of tumor extension beyond the gland or multicentricity. Molecular tests are not necessary to choose between AS and surgery or, in the latter case, between lobectomy and total thyroidectomy. The presence of RAS or other RAS-like mutations or BRAFV600E or other BRAF V600E-like mutations should not modify the management cited above; however, the rare cases of mPTC exhibiting high-risk mutations, like in the TERT promoter or p53, are not candidates for AS.

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP): a review for clinicians

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is an encapsulated or clearly delimited, noninvasive neoplasm with a follicular growth pattern and nuclear features of papillary thyroid carcinoma (PTC). It is considered a 'pre-malignant' lesion of the RAS-like group. Ultrasonography (US), cytology and molecular tests are useful to suspect thyroid nodules that correspond to NIFTP but there is wide overlap of the results with the encapsulated follicular variant of PTC (E-FVPTC). In these nodules that possibly or likely correspond to NIFTP, if surgery is indicated, lobectomy is favored over total thyroidectomy. The diagnosis of NIFTP is made after complete resection of the lesion by observing well-defined criteria. In the case of patients who received the diagnosis of FVPTC and whose pathology report does not show findings of malignancy (lymph node metastasis, extrathyroidal invasion, vascular/capsular invasion), if the tumor was encapsulated or well delimited, the slides can be revised by an experienced pathologist to determine whether the diagnostic criteria of NIFTP are met, but special attention must be paid to the adequate representativeness of the capsule and tumor. Since NIFTP is not 'malignant', tumor staging is not necessary and patients are not submitted to thyroid cancer protocols or guidelines. We believe that patients with NIFTP without associated malignancy and without nodules detected by US of the remnant lobe (if submitted to lobectomy) can be managed like those with follicular adenoma.

Repeat Ultrasonography in the First Years after Therapy with Radioiodine Is Not Necessary in Most Patients with Papillary Thyroid Carcinoma when Postoperative Ultrasonography Is Negative: A Reduction of Costs and False-Positives

BACKGROUND

Periodic ultrasonography (US) examination is recommended in many patients with papillary thyroid carcinoma (PTC) after treatment with radioactive iodine (RAI), but recurrences are confirmed in few cases. This study determined whether the indication of US in the first years after treatment with RAI can be selective when postoperative US and posttherapy whole-body scanning (RxWBS) ruled out persistent neck disease.

METHODS

This was a prospective study. Two hundred and fifty-four patients with PTC (242 of intermediate risk) undergoing thyroidectomy and RAI, who had no apparent disease at the time of initial therapy (including negative postoperative US and RxWBS), were studied. The patients were followed up for 5 years after treatment with RAI by annual US.

RESULTS

At the end of 5 years, 47 patients (18.5%) had at least one suspicious US, but neck recurrence was confirmed in only 4 patients (1.5% of all patients and 8.5% of those with suspicious US). The remaining cases were considered false-positives. US did not reveal disease in the first or second year after treatment with RAI in any patient. In the third, fourth, and fifth year after treatment with RAI, considering only patients with unstimulated Tg < 1 ng/mL in these assessments, US revealed disease in 0, 1 (0.4%), and 1 (0.4%) patient, respectively.

CONCLUSION

The results suggest that low- or intermediate-risk patients with PTC without persistent disease after thyroidectomy (including negative postoperative US and RxWBS) do not require repeat US examination in the first two years after treatment with RAI. In the following years until the fifth year, US can be restricted to patients with Tg ≥1 ng/mL.

Are Papillary Thyroid Carcinomas That Are Candidates for Active Surveillance in Fact Classical Microcarcinomas Restricted to the Gland?

BACKGROUND

Patients with small papillary thyroid carcinomas (PTC) can currently be maintained under active surveillance (AS). The recommended criteria are the following: adult individual, tumor ≤1 cm and not adjacent to the trachea or recurrent laryngeal nerve, cytology non-suggestive of the aggressive subtype, absence of lymph node (LN) involvement and extrathyroidal extension (ETE) on ultrasonography (US), and absence of clinical distant metastases. This study aimed to evaluate the frequency of the following peri- and postoperative findings in patients who met the criteria for PTC being candidate for AS: tumor > 1 cm, aggressive subtype or vascular invasion, ETE, clinical LN metastases (cN1), and distant metastases.

METHODS

We reviewed the results of peri- and postoperative evaluation and histology of patients with a preoperative diagnosis of PTC who would currently be candidates for AS.

RESULTS

There were 124 patients (102 women) with nodules ≤1 cm (range 4-10 mm). All nodules corresponded to papillary microcarcinomas on histology and none of them were > 1 cm. Only one microcarcinoma (0.8%) was of the tall-cell subtype. Vascular invasion was found in 10 microcarcinomas (8%). None of the microcarcinomas were staged as T3b or T4, although microscopic ETE was observed in 25 tumors (20%). In 8 patients (6.4%), central LN involvement was suspected during perioperative evaluation and was confirmed by histology (cN1a). None of the patients had distant metastases (M0).

CONCLUSION

Findings that define an intermediate risk of recurrence and favor total thyroidectomy were observed in 31.5% of patients with PTC who are candidates for AS.

Long-Term Follow-Up in Patients with Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features (NIFTP) Without a Suspicion of Persistent Disease in Postoperative Assessment

The objective was to determine whether negative assessment after surgery is a predictor of no relevant change of the results in subsequent evaluations in patients with noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). Six months after surgery, "absence of persistent disease" was defined when concentration of thyroglobulin (Tg) is ≤2 ng/ml in patients undergoing total thyroidectomy and ≤10 ng/ml in those undergoing lobectomy, in the absence of antithyroglobulin antibodies (TgAb), and neck ultrasonography (US) without abnormalities. One hundred thirteen patients met the definition of "absence of persistent disease". The patients were followed up for 18-150 months. None of the patients developed structural disease. In the 56 patients undergoing total thyroidectomy, 380 Tg measurements were obtained and an increase in concentrations was not observed in any of them. During the same period, 332 US scans were performed and a suspicious lymph node was detected on only one occasion, but was not metastatic on fine needle aspiration (FNA). In the 57 patients undergoing lobectomy, 382 Tg measurements were obtained and increases or persistent concentrations>10 ng/ml were not observed in any patient. During the same period, 376 US scans were performed and nodules with an indication for FNA were detected in 4 patients, but malignancy was not confirmed in any of them. Finally, TgAb were not elevated in any of the 762 measurements obtained from the 113 patients. After complete resection of NIFTP, negative postoperative assessment can be used to exclude the need for long-term repetition of these tests.

Influence of chronic lymphocytic thyroiditis on the risk of persistent and recurrent disease in patients with papillary thyroid carcinoma and elevated antithyroglobulin antibodies after initial therapy

INTRODUCTION

In patients with papillary thyroid carcinoma who have negative serum thyroglobulin after initial therapy, the risk of structural disease is higher among those with elevated antithyroglobulin antibodies compared to patients without antithyroglobulin antibodies. Other studies suggest that the presence of chronic lymphocytic thyroiditis is associated with a lower risk of persistence/recurrence of papillary thyroid carcinoma.

OBJECTIVE

This prospective study evaluated the influence of chronic lymphocytic thyroiditis on the risk of persistence and recurrence of papillary thyroid carcinoma in patients with negative thyroglobulin but elevated antithyroglobulin antibodies after initial therapy.

METHODS

This was a prospective study. Patients with clinical examination showing no anomalies, basal Tg<1ng/mL, and elevated antithyroglobulin antibodies 8-12 months after ablation were selected. The patients were divided into two groups: Group A, with chronic lymphocytic thyroiditis on histology; Group B, without histological chronic lymphocytic thyroiditis.

RESULTS

The time of follow-up ranged from 60 to 140 months. Persistent disease was detected in 3 patients of Group A (6.6%) and in 6 of Group B (8.8%) (p=1.0). During follow-up, recurrences were diagnosed in 2 patients of Group A (4.7%) and in 5 of Group B (8%) (p=0.7). Considering both persistent and recurrent disease, structural disease was detected in 5 patients of Group A (11.1%) and in 11 of Group B (16.1%) (p=0.58). There was no case of death related to the disease.

CONCLUSION

Our results do not support the hypothesis that chronic lymphocytic thyroiditis is associated with a lower risk of persistent or recurrent disease, at least in patients with persistently elevated antithyroglobulin antibodies after initial therapy for papillary thyroid carcinoma.

Recombinant human TSH versus thyroid hormone withdrawal in adjuvant therapy with radioactive iodine of patients with papillary thyroid carcinoma and clinically apparent lymph node metastases not limited to the central compartment (cN1b)

Objective

To compare the short- and long-term outcomes of adjuvant therapy with radioactive iodine (RAI) preceded by the administration of recombinant human TSH (rhTSH) versus thyroid hormone withdrawal (THW) in patients with papillary thyroid carcinoma and clinically apparent lymph node metastases not limited to the central neck compartment (cN1b).

Subjects and methods

The sample consisted of 178 cN1b patients at intermediate risk who underwent total thyroidectomy with apparently complete tumor resection [including postoperative ultrasonography (US) without anomalies] and who received adjuvant therapy with RAI (30-100 mCi) preceded by the administration of rhTSH (n = 91) or THW (n = 87).

Results

One year after RAI, the rates of excellent response to therapy, i.e., nonstimulated thyroglobulin (Tg) ≤ 0.2 ng/mL with negative antithyroglobulin antibodies and negative neck US, and of structural disease were similar for the two preparations (84% and 4.5%, respectively, in both groups). During follow-up (median 66 months), the rate of structural or biochemical (nonstimulated Tg > 1 ng/mL, with increment) recurrence was also similar in the two groups (4.5%). In the last assessment, the percentage of patients without evidence of disease, i.e., nonstimulated Tg < 1 ng/mL and no evidence of structural disease, was similar for the two preparations [92.3% in the rhTSH group and 97.7% in the THW group (p = 0.17)].

Conclusion

Preparation with rhTSH was equally effective (short- and long-term) as THW for adjuvant RAI therapy of cN1b patients at intermediate risk and with apparently complete tumor resection.

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features

Recently, it was proposed that some papillary thyroid carcinomas (PTC) will no longer be termed 'cancer' and are christened as 'noninvasive follicular thyroid neoplasm with papillary-like nuclear features' (NIFTP). As this is a recent definition, little information is available about NIFTP. The objective of this study was to report the frequency, ultrasonographic appearance, cytology result and long-term evolution of cases of NIFTP seen at our institution. We excluded tumours ≤1 cm. The sample consisted of 129 patients. Sixty-four patients were submitted to total thyroidectomy and 65 to lobectomy. These patients with NIFTP did not receive radioiodine. NIFTP corresponded to 15% of cases diagnosed as PTC >1 cm. An ultrasonographic appearance considered to be of low suspicion for malignancy was common in NIFTP (32.5%), whereas a highly suspicious appearance was uncommon (5%). NIFTP frequently exhibited indeterminate cytology (62%), while malignant cytology was uncommon (4%). The patients were followed up for 12-146 months (median 72 months) after surgery. None of the patients developed structural disease during follow-up. Comparing the concentrations of thyroglobulin (Tg) and anti-Tg antibodies (TgAb) obtained 6-12 months after surgery and in the last assessment, none of the patients exhibited an increase in these markers.

Can the follow-up of patients with papillary thyroid carcinoma of low and intermediate risk and excellent response to initial therapy be simplified using second-generation thyroglobulin assays?

OBJECTIVE

In view of the low probability of recurrence, the cost-effective follow-up of patients with papillary thyroid carcinoma (PTC) of low or intermediate risk and excellent response to initial therapy represents a challenge. This study evaluated the cases of structural recurrence among these patients.

PATIENTS

The sample comprised 578 patients with PTC of low or intermediate risk, who were submitted to total thyroidectomy with or without (131) I therapy and exhibited an excellent response to initial therapy defined based on nonstimulated thyroglobulin (Tg) ≤0·2 ng/ml and negative neck ultrasonography (US).

RESULTS

Twelve patients (2%) showed structural recurrence. At the time when recurrence was 'confirmed', Tg elevation had not occurred in only two patients, one with lymph node metastases <1 cm detected by US and the other with pulmonary metastases. Antithyroglobulin antibodies (TgAb) were undetectable in both patients. The first alteration observed in patients with recurrence was Tg elevation in six patients, Tg elevation associated with suspicious US in three, and suspicious US in two. An increase in TgAb was not the first alteration in any of the patients. Among the 560 patients who continued to have Tg ≤ 0·2 ng/ml, US permitted the detection of only one neck recurrence. Measurement of TgAb did not detect any recurrence.

CONCLUSION

Our results confirm that in patients with PTC of low or intermediate risk an excellent response to initial therapy can be defined based on nonstimulated Tg ≤ 0·2 ng/ml. Follow-up consisting only of clinical examination and periodic measurement of Tg with a second-generation assay may be sufficient.

Screening for Hyperparathyroidism by Measurement of Calcium in Patients Undergoing Thyroid Surgery: A Prospective Study

This study screened for asymptomatic primary hyperparathyroidism (PHPT) by measuring calcium (Ca) before thyroid surgery. The study was prospective. A total of 676 patients without a suspicion of PHPT were studied. PHPT was defined as elevated Ca (in 2 measurements) in the presence of PTH>25 pg/ml and in the absence of hypocalciuria. PHPT was diagnosed in 5 patients (0.74%), all of them women. One of the 5 patients with PHPT had no indication for parathyroidectomy (PTx) according to current guidelines. Parathyroid adenoma was easily identified during perioperative assessment of thyroid surgery in 3 patients. In the other 2 patients (0.3%), localization of the adenoma required specific exploration, which was only performed because of the preoperative diagnosis of PHPT. Normalization of Ca and PTH was achieved in all 5 patients. In conclusion, in patients without a clinical or ultrasonographic suspicion of PHPT, approximately 300 individuals should be screened before thyroid surgery to avoid one reoperation (PTx) due to PHPT, which does not seem to be cost-effective.

Low postoperative nonstimulated thyroglobulin as a criterion for the indication of low radioiodine activity in patients with papillary thyroid cancer of intermediate risk 'with higher risk features'

OBJECTIVE

This study evaluated low-activity (131) I therapy in patients with papillary thyroid carcinoma (PTC) of intermediate risk 'with higher risk features' who had low nonstimulated thyroglobulin (Tg) after thyroidectomy.

DESIGN AND PATIENTS

This was a prospective study including 102 patients with tumours >1 cm and aggressive histology; and/or >3 positive lymph node (LN) or LN >1·5 cm or exhibiting macroscopic extracapsular extension, and clinically apparent (cN1); and/or a combination of a tumour >4 cm, microscopic extrathyroidal extension and LN metastases (cN1). After thyroidectomy, all patients had nonstimulated Tg < 0·3 ng/ml and negative antithyroglobulin antibodies (TgAb) and neck ultrasonography (US). The patients were treated with a low activity of (131) I (1110 or 1850 MBq).

RESULTS

Post-therapy whole-body scanning (RxWBS) showed ectopic uptake in four patients. When evaluated 12 months after (131) I therapy, nonstimulated Tg ≤ 0·2 ng/ml with negative TgAb and US, defined as excellent response to initial therapy, was achieved in 101 patients (99%). Only one patient with positive initial RxWBS had structural disease. During follow-up, four patients (4%) relapsed, including LN metastases in two, pulmonary metastases in one, and elevated Tg in one. The other 98 patients remained with nonstimulated Tg ≤ 0·2 ng/ml and negative TgAb and US. There was no case of death due to the tumour.

CONCLUSIONS

We conclude that in intermediate-risk patients 'with higher risk features', low nonstimulated Tg measured with a second-generation assay can be used as criterion for the administration of low (131) I activities (1850 MBq or less).

Comparison of Antithyroglobulin Antibody Concentrations Before and After Ablation with 131I as a Predictor of Structural Disease in Differentiated Thyroid Carcinoma Patients with Undetectable Basal Thyroglobulin and Negative Neck Ultrasonography

BACKGROUND

Patients with differentiated thyroid carcinoma are submitted to a first assessment several months after initial therapy to evaluate their response to treatment. At that assessment, measurement of basal thyroglobulin (Tg) and antithyroglobulin antibodies (TgAb) and neck ultrasonography (US) are recommended. Serum Tg may be falsely negative in the presence of TgAb, and the management of patients with negative Tg but positive TgAb represents a challenge. The objective of this study was to correlate the variation in TgAb concentrations (comparison before and after ablation with (131)I) with the risk of structural disease.

METHODS

The sample consisted of 116 low- or intermediate-risk patients who had undetectable Tg, negative US at initial assessment, and positive TgAb 8-12 months after thyroidectomy and ablation with (131)I.

RESULTS

Comparison of TgAb concentrations before and after ablation with (131)I showed a reduction of >50% in 56 patients (group A), a reduction of <50% in 35 patients (group B), and an increase in 25 patients (group C). Metastases were detected in 5/116 (4.3%) patients during initial assessment (lymph nodes in two, pulmonary in two, and bone in one). They were diagnosed in 0/56, 2/35 (5.7%), and 3/25 (12%) patients of groups A, B, and C, respectively. During follow-up, metastases were detected in 7/111 (6.3%) patients (lymph nodes in six, and pulmonary in one). They occurred in 1/56 (1.8%), 3/33 (9%), and 3/22 (13.6%) patients of groups A, B, and C, respectively. Thus, structural disease was found in 1.8%, 14.3%, and 24% of groups A, B, and C, respectively. This rate was 4% in low-risk patients and 15.4% in intermediate-risk patients.

CONCLUSIONS

Among patients with undetectable Tg, negative US, and positive TgAb after ablation with (131)I, the frequency of structural disease was <5% in patients, with >50% reduction in TgAb. Among patients without a significant reduction in TgAb, approximately 10% of low-risk patients and >20% of intermediate-risk patients had structural disease. These results help define the indication for imaging methods other than US during initial assessment and long-term follow-up.

Is 131I ablation necessary for patients with low-risk papillary thyroid carcinoma and slightly elevated stimulated thyroglobulin after thyroidectomy?

OBJECTIVE

This prospective study evaluated the recurrence rate in low-risk patients with papillary thyroid cancer (PTC) who presented slightly elevated thyroglobulin (Tg) after thyroidectomy and who did not undergo ablation with131I.

SUBJECTS AND METHODS

The study included 53 low-risk patients (nonaggressive histology; pT1b-3, cN0pNx, M0) with slightly elevated Tg after thyroidectomy (> 1 ng/mL, but ≤ 5 ng/mL after levothyroxine withdrawal or ≤ 2 ng/mL after recombinant human TSH).

RESULTS

The time of follow-up ranged from 36 to 96 months. Lymph node metastases were detected in only one patient (1.9%). Fifty-two patients continued to present negative neck ultrasound. None of these patients without apparent disease presented an increase in Tg.

CONCLUSIONS

Low-risk patients with PTC who present slightly elevated Tg after thyroidectomy do not require ablation with 131I.

Low postoperative nonstimulated thyroglobulin as a criterion to spare radioiodine ablation

This study evaluated the recurrence rate in patients with papillary thyroid carcinoma (PTC) who had low nonstimulated thyroglobulin (Tg), measured with a second-generation assay, after total thyroidectomy and who were not submitted to ablation with (131)I. The objective was to define whether low postoperative nonstimulated Tg can be used as a criterion to spare patients with PTC from therapy with (131)I. This was a prospective study including 222 patients with PTC (except for microcarcinoma restricted to the thyroid and tumor with extensive extrathyroid invasion (pT4), aggressive histology, extensive lymph node (LN) involvement, or known residual disease). After thyroidectomy, all patients had nonstimulated Tg<0.3 ng/ml, negative antithyroglobulin antibodies (TgAb) and neck ultrasonography (US) showing no anomalies. Because of this finding, the patients were not submitted to ablation with (131)I. The time of follow-up ranged from 15 to 102 months (median 62 months). Of the 222 patients, 217 (97.7%) continued to have nonstimulated Tg <0.3 ng/ml and negative US. Tg was undetectable in the last assessment in 185 of these patients and detectable in 32. Five patients (2.2%) exhibited an increase in Tg, and LN metastases were detected in 4 (structural recurrence). One patient progressed to an increase in Tg, but disease was not detected by the imaging methods (biochemical recurrence). The results obtained here suggest that patients with PTC who have low nonstimulated Tg (measured with a second-generation assay and in the absence of TgAb) and negative neck US after thyroidectomy do not require ablation with (131)I.

Patients with Papillary Thyroid Carcinoma at Intermediate Risk of Recurrence According to American Thyroid Association Criteria Can Be Reclassified as Low Risk When the Postoperative Thyroglobulin Is Low

BACKGROUND

According to American Thyroid Association (ATA), all patients with papillary thyroid carcinoma (PTC) should initially be classified regarding the risk of tumor recurrence. If a very high postoperative thyroglobulin (Tg) classifies patients as high risk of recurrence, it is reasonable to hypothesize that, at the other extreme, a low Tg may reclassify patients from intermediate to low risk. The objective of this study was to evaluate the rate of persistent/recurrent disease in intermediate-risk patients with low postoperative (before 131I) Tg, thereby evaluating whether these patients can be reclassified as low risk based on this finding already at the time of initial therapy rather than one to two years after radioiodine therapy.

METHODS

A total of 181 patients with the following characteristics were evaluated: (i) diagnosis of PTC; (ii) submitted to total thyroidectomy with lymph node dissection in the case of a suspicion of metastases based on preoperative ultrasonography (US) or perioperative evaluation (cN1); (iii) apparently without persistent tumor after surgery; (iv) a postoperative stimulated Tg (sTg) ≤2 ng/mL and negative anti-Tg antibodies (TgAb); and (v) considered to be at intermediate risk by ATA criteria.

RESULTS

When evaluated 9-12 months after radioiodine therapy, 170 patients (94%) had a sTg <1 ng/mL and negative TgAb and a negative neck US (excellent response). Ten patients (5.5%) had a sTg >1 ng/mL (≤2 ng/mL) in the absence of apparent disease detected by imaging methods (indeterminate response). US detected cervical lymph node metastases (not detected at the time of 131I therapy) in one patient (incomplete structural response). During follow-up, recurrence was observed in 5/180 (2.7%) patients without apparent disease in the initial assessment. Thus, persistent or recurrent disease occurred in only 3.3% of cases. The 175 patients without tumor persistence/recurrence were not submitted to any additional therapy, and all had a Tg/thryoxine <1 ng/mL in the last assessment. There was no case of death related to the disease.

CONCLUSIONS

This study suggests that intermediate-risk patients (according to ATA criteria) with a postoperative sTg ≤2 ng/mL can be reclassified as low risk already at the time of initial therapy.

Serum Thyroglobulin Measured With a Second-Generation Assay in Patients Undergoing Total Thyroidectomy Without Radioiodine Remnant Ablation: A Prospective Study

BACKGROUND

Follow-up consisting of the measurement of nonstimulated serum thyroglobulin (Tg) combined with neck ultrasonography is recommended for patients with papillary thyroid carcinoma without indication for radioiodine ablation. There is no recommendation of thyrotropin suppression during this follow-up. New-generation Tg assays have been increasingly used, but few studies involve patients submitted only to thyroidectomy and they have several limitations. The objective of this prospective study was to define expected concentrations of nonstimulated Tg measured with a second-generation assay after total thyroidectomy in the absence of tumor.

METHODS

Serum Tg was measured using a second-generation assay in 69 patients without tumor and serum thyrotropin between 0.5 and 2 mIU/L, 3, 6, 12, and 24 months after total thyroidectomy. All patients had undetectable anti-Tg antibodies.

RESULTS

Serum Tg was undetectable in 44.4%, 57%, 62.5%, and 62.1% of the patients 3, 6, 12, and 24 months after thyroidectomy, respectively, and was ≤0.5 ng/mL in 60.3%, 80%, 90.6%, and 90.9% of patients. All patients had a Tg≤2 ng/mL 6 months after thyroidectomy, and 97% had a Tg≤1 ng/mL 24 months after surgery. There was no case of Tg conversion from undetectable to detectable and none of the patients presented an increase in Tg.

CONCLUSIONS

An important decline in serum Tg occurred between 3 and 6 months after total thyroidectomy. One year after surgery, Tg was undetectable in approximately 60% of the patients and was ≤2 ng/mL in all of them.

Is Stimulated Thyroglobulin Necessary after Ablation in All Patients with Papillary Thyroid Carcinoma and Basal Thyroglobulin Detectable by a Second-Generation Assay?

Objective. To evaluate the percentage of elevated stimulated thyroglobulin (sTg) and persistent or recurrent disease (PRD) in patients with detectable basal Tg < 0.3 ng/mL. Methods. The sample consisted of 130 patients with papillary thyroid carcinoma (PTC) who were at low risk of PRD and who had neck ultrasound (US) without abnormalities, negative anti-Tg antibodies (TgAb), and detectable basal Tg < 0.3 ng/mL about 6 months after ablation. Results. sTg was <1 ng/mL in 88 patients (67.7%), between 1 and 2 ng/mL in 26 (20%), and ≥2 ng/mL in 16 (12.3%). Imaging methods revealed the absence of tumors in 16 patients with elevated sTg. During follow-up, Tg increased to 0.58 ng/mL in one patient and lymph node metastases were detected. Sixty-nine patients continued to have detectable Tg < 0.3 ng/mL and US revealed recurrence in only one patient. Sixty patients progressed to persistently undetectable Tg without apparent disease on US. Conclusions. In low-risk patients with PTC who have detectable basal Tg < 0.3 ng/mL after ablation, negative TgAb, and US, persistent disease is rare and eventual recurrences can be detected by basal Tg elevation and/or subsequent US assessments, with follow-up without sTg being an "alternative" to Tg stimulation.

Is empirical radioactive iodine therapy still a valid approach to patients with thyroid cancer and elevated thyroglobulin?

BACKGROUND

At present, empirical radioactive iodine therapy is recommended for patients with thyroid cancer and elevated thyroglobulin (Tg) after initial therapy when neck ultrasonography (US), chest computed tomography (CT), and 18-fluorodeoxyglucose positron emission tomography (FDG-PET) do not reveal metastases. The objective of this study was to determine whether empirical (131)I therapy is indeed useful in these patients.

METHODS

Patients with papillary thyroid cancer submitted to total thyroidectomy followed by remnant ablation with (131)I in whom whole-body scanning at the time of ablation (WBS-ablation) did not reveal metastases and who had elevated Tg after initial therapy were selected. Included in the study were patients with basal Tg >2 ng/mL or Tg >5 ng/mL after stimulation with recombinant human thyrotropin or Tg >10 ng/mL after levothyroxine withdrawal for 4 weeks. All patients were first investigated by neck US and chest CT. FDG-PET/CT was performed in patients with negative US and CT. The final sample of this study consisted of patients with negative US, CT, and FDG-PET/CT. These patients received an activity of 100 mCi (131)I and were submitted to posttherapy WBS (RxWBS).

RESULTS

Among the 24 patients receiving empirical (131)I therapy, no ectopic uptake was seen in 23 and mild uptake in the thyroid bed (<0.5%) in 15. Only one patient presented pulmonary metastases detected by RxWBS. Disease was observed in two other patients during short-term follow-up (mean 22 months), one with lymph node metastases diagnosed by a repeat US and one with bone metastases diagnosed by CT and FDG-PET scans.

CONCLUSIONS

We conclude that RxWBS rarely reveals disease in patients with elevated Tg after ablation, but with negative findings on WBS-ablation, US, CT, and FDG-PET. In this situation, empirical (131)I therapy should be restricted to patients with documented progression of serum Tg.