Prognostic significance of FDG PET/CT on the follow-up of patients of differentiated thyroid carcinoma with negative 131I whole-body scan and elevated thyroglobulin levels: correlation with clinical and histopathologic characteristics and long-term follow-up data.

AIMS: This study aimed (a) to determine the clinical and histopathologic factors that are related to FDG avidity in the recurrence/metastases of patients with differentiated thyroid carcinoma (DTC) who present with elevated thyroglobulin (Tg) levels and negative 131I whole-body scans (WBSs), (b) to clarify Tg cutoff levels in this setting, and (c) to evaluate the impact of PET/CT on patient management strategies and hence to critically look into the importance of PET/CT in combination with Tg in clinical decision making. METHODS: A total of 105 patients with DTC with negative 131I WBS and neck ultrasound but elevated Tg, who underwent FDG PET/CT for the suspicion of recurrent/metastatic disease, were included in this analysis. All patients had previously undergone total thyroidectomy and radioiodine ablation/therapy. PET/CT results were correlated with Tg levels and clinical and histopathologic characteristics of the primary tumor compared with the follow-up data. RESULTS: PET/CT was true-positive in 69 patients (of which 23 had surgically amenable disease), true-negative in 20, false-positive in 6 patients and false-negative in 10 patients. Extrathyroidal spread was an independent risk factor related to FDG-avid recurrence. Tumor size was significantly higher in PET-positive patients than others, 2.25 (1.8) versus 1.5 (1.1) cm, P = 0.02. Significant correlation was observed between PET positivity and high Tg levels (P = 0.0001). Receiver operating characteristic curve analysis demonstrated a Tg cutoff of 1.9 ng/mL under thyroid-stimulating hormone suppression, 38.2 ng/mL with thyroid-stimulating hormone stimulation. Among PET-negative patients, no recurrence was detected in patients with undetectable/suppressible Tg in on-therapy state. CONCLUSIONS: PET positivity correlated with extrathyroidal spread, and elevated Tg in recurrent/metastatic DTC. FDG PET/CT in combination with Tg levels was crucial in defining management strategies in patients with DTC with negative 131I WBS. A negative FDG PET/CT scan predicts a favorable prognosis and lack of recurrence on follow-up in patients with "suppressible Tg" levels in the on-therapy state despite significant elevation of Tg in the off-therapy state.

Value of axillary lymphoscintigraphy in patients with operated breast carcinoma.

PURPOSE: To evaluate axillary dissection with axillary lymphoscintigraphy (ALS) in postoperative patients with breast carcinoma and its role in adjuvant radiotherapy (RT). Additionally, to define axillary dissection as complete and incomplete with ALS and to correlate it with the number of removed lymph nodes. MATERIAL AND METHODS: In the last two years, 121 women were studied four weeks after operation. Bilateral second interdigital subcutaneous injections were performed for ALS. Complete and incomplete axillary dissection were interpreted according to the number of surgically removed lymph nodes. ALS was interpreted as complete if no accumulation was shown. RESULTS: There was a good correlation between the number of surgically removed lymph nodes and complete and incomplete interpretation on ALS (p < 0.004). The number of removed lymph nodes was equal to or greater than 15 in 72% patients with complete dissection according to ALS. Of 48 patients with surgically incomplete axillary dissection, 18 (38%) showed no accumulation in the axillary region, while 25 of 68 (37%) patients with surgically complete dissection showed accumulation in the axillary region and were interpreted as incomplete according to ALS. Indication of RT was changed after ALS in patients with 1 to 3 involved lymph nodes. While RT was not considered in 12 of these patients before ALS, they were included in RT planning. On the other hand, 17 patients, considered for RT previously, were excluded from RT planning after ALS. CONCLUSION: Evaluation of axillary dissection with ALS especially in suspicious patients with 1 to 3 lymph node metastases might prevent unnecessary morbidity and can be useful in selecting patients who truly need axillary irradiation.