Low-risk papillary thyroid cancer: times are changing

Inability of Radioiodine Remnant Ablation to Improve Postoperative Outcome in Adult Patients with Low-Risk Papillary Thyroid Carcinoma

OBJECTIVE

To determine whether radioiodine remnant ablation (RRA) reduces cause-specific mortality (CSM) or tumor recurrence (TR) rate after bilateral lobar resection (BLR).

PATIENTS AND METHODS

There were 2952 low-risk adult papillary thyroid cancer (LRAPTC) patients (with MACIS scores <6) who underwent potentially curative BLR during 1955-2014. During 1955-1974, 1975-1994, and 1995-2014, RRA was administered in 3%, 49%, and 28%. Statistical analyses were performed using SAS software.

RESULTS

During 1955-1974, the 20-year CSM and TR rates after BLR alone were 1.0% and 6.8%; rates after BLR+RRA were 0% (P=.63) and 5.9% (P=.82). During 1975-1994, post-BLR 20-year rates for CSM and TR were 0.3% and 7.5%; after BLR+RRA, rates were higher at 0.9% (P=.31) and 12.8% (P=.01). When TR rates were examined separately for 448 node-negative and 317 node-positive patients, differences were nonsignificant. In 1995-2014, post-BLR 20-year CSM and TR rates were 0% and 9.2%; rates after BLR+RRA were higher at 1.4% (P=.19) and 21.0% (P<.001). In 890 pN0 cases, 15-year locoregional recurrence rates were 3.4% after BLR and 3.7% after BLR+RRA (P=.99). In 740 pN1 patients, 15-year locoregional recurrence rates were 10% higher after BLR+RRA compared with BLR alone (P=.01). However, this difference became nonsignificant when stratified by numbers of metastatic nodes.

CONCLUSION

RRA administered to LRAPTC patients during 1955-2014 did not reduce either the CSM or TR rate. We would therefore not recommend RRA in LRAPTC patients undergoing BLR with curative intent.

Papillary Thyroid Carcinoma (PTC) in Children and Adults: Comparison of Initial Presentation and Long-Term Postoperative Outcome in 4432 Patients Consecutively Treated at the Mayo Clinic During Eight Decades (1936-2015)

BACKGROUND

Contemporary guidelines for managing PTC advise an approach wherein primary tumor and regional metastases (RM) are completely resected at first surgery and radioiodine remnant ablation (RRA) is restricted to high-risk patients, policies our group has long endorsed. To assess our therapeutic efficacy, we studied 190 children and 4242 adults consecutively treated during 1936-2015.

SUBJECTS AND METHODS

Mean follow-up durations for children and adults were 26.9 and 15.2 years, respectively. Bilateral lobar resection was performed in 86% of children and 88% of adults, followed by RRA in 30% of children and 29% of adults; neck nodes were excised in 86% of children and 66% of adults. Tumor recurrence (TR) and cause-specific mortality (CSM) details were taken from a computerized database.

RESULTS

Children, when compared to adults, had larger primary tumors which more often were grossly invasive and incompletely resected. At presentation, children, as compared to adults, had more RM and distant metastases (DM). Thirty-year TR rates were no different in children than adults at any site. Thirty-year CSM rates were lower in children than adults (1.1 vs. 4.9%; p = 0.01). Comparing 1936-1975 (THEN) with 1976-2015 (NOW), 30-year CSM rates were similar in MACIS <6 children (p = 0.67) and adults (p = 0.08). However, MACIS <6 children and adults in 1976-2015 had significantly higher recurrence at local and regional, but not at distant, sites. MACIS 6+ adults, NOW, compared to THEN, had lower 30-year CSM rates (30 vs. 47%; p < 0.001), unassociated with decreased TR at any site.

CONCLUSIONS

Children, despite presenting with more extensive PTC when compared to adults, have postoperative recurrences at similar frequency, typically coexist with DM and die of PTC less often. Since 1976, both children and adults with MACIS <6 PTC have a <1% chance at 30 years of CSM; adults with higher MACIS scores (6 or more) have a 30-year CSM rate of 30%.

Current dilemmas in the diagnosis and management of follicular thyroid tumors

Follicular carcinoma (FTC) is a relatively uncommon type of differentiated thyroid carcinoma. Guidelines have often dealt with FTC and papillary thyroid cancer as a single disease. Over the last decade, however, a better understanding of these two types of thyroid cancer indicates that they cannot be analysed together. Neither ultrasonography nor fine-needle aspiration cytology can provide a clear distinction between FTC and follicular adenoma. New molecular diagnostic techniques may be used to identify a subpopulation of follicular neoplasms with a low probability of being malignant. Diagnostic surgery-usually hemithyroidectomy- is recommended for most thyroid follicular lesions without a certain preoperative diagnosis. If FTC is diagnosed most-perhaps not all- patients will require a completion thyroidectomy. While widely invasive FTC usually does not pose diagnostic or therapeutic doubts, consensus on the diagnosis of non-invasive follicular lesions is still lacking. Prognosis of FTC is mostly dependent on local invasion and distant metastasis that, in turn, correlate with tumor size.

THERAPY OF ENDOCRINE DISEASE: Central neck dissection: a step forward in the treatment of papillary thyroid cancer

Since its introduction in the '70s and '80s, CND for papillary cancer is here to stay. Compartment VI should always be explored during surgery for papillary thyroid carcinoma (PTC) for obvious lymph node metastases. These can be easily spotted by an experienced surgeon or, eventually, by frozen section. No doubt, obvious nodal disease in the Delphian, paratracheal and subithsmic areas should be dissected in a comprehensive manner (therapeutic central neck dissection), avoiding the selective removal of suspicious nodes. Available evidence for routine prophylactic CND is not completely satisfactory. Our group's opinion, however, is that it reduces or even eliminates the need for repeat surgery in the central neck, better defines the extent (and stage) of the disease and provides a further argument against routine radioiodine ablation. Thus, PTC is becoming more and more a surgical disease that can be cured by optimized surgery alone in the majority of cases. Prophylactic CND, however, involves a higher risk for the parathyroid function and should be skilfully performed, preferably only on the same side as the primary tumour and preserving the cervical portion of the thymus.

Central neck dissection in the treatment of well-differentiated thyroid cancer

Therapeutic central compartment neck dissection (CCND) is required for confirmed nodal metastasis in patients with differentiated thyroid cancer. The need for routine prophylactic CCND in patients with papillary thyroid cancer is controversial. This article presents the current evidence to inform the debate against the background of the recommendations of US and British thyroid cancer guidelines. Potential advantages of pCCND include reduced local recurrence, preventing the need for further central compartment surgery and improved staging. Opponents claim that there is no proven patient benefit and that there is increased risk of recurrent laryngeal nerve injury and hypocalcemia.

Local recurrence of papillary thyroid cancer

Management of advanced papillary thyroid cancer (PTC >10 mm) is changing its focus. Mortality was the main outcome measure for patients treated before the 90s. In the past two decades, however, most patients diagnosed with PTC belong to the very low risk of death group. On the other hand, local recurrence of PTC remains a clinical problem, with rates up to 25% depending on the presence of nodal metastasis, tumor diameter, and the skill of the surgeon to completely remove the primary tumor and the associated lymph node metastasis at first-time thyroidectomy. After optimized surgery (total thyroidectomy plus central neck dissection), radioiodine ablation has very little influence on lymph node recurrence that now presents mostly as lateral neck node metastasis that was overlooked or incompletely resected at the time of initial surgery.

Thyroglobulin test at 3 weeks after surgery in well-differentiated thyroid cancer and its predictive value: the role of endocrine–metabolic status

Aim & methods: The present pilot study included 50 differentiated thyroid cancer (DTC) patients (mean age: 45.8 ± 1.8 years, range: 18–73 years) who were followed after surgery for in average 30.0 ± 2.6 months. All patients were subdivided into two groups as having either <2 ng/ml or ≥2 ng/ml blood thyroglobulin level 3 weeks after the operation (3-WTT). Results: Subsequent tumor progression was revealed more often in patients with higher thyroglobulinemia (≥2 ng/ml) in both low- and high-risk DTC groups. Patients with high-risk DTC and 3-week thyroglobulin levels ≥2 ng/ml were more likely to have a higher pre-surgical thyrotropin (TSH) levels. On the contrary, patients with low-risk DTC and 3-week thyroglobulin level ≥2 ng/ml demonstrated tendency to higher preoperative serum insulin levels and higher BMI. Conclusion: These differential findings could suggest that, whereas maximal suppression of TSH is reasonable in high-risk DTC patients, in low-risk DTC patients, for whom this is not justified, a moderate TSH suppression supplemented by multivalent drugs, such as antidiabetic biguanide metformin, could be advised.