Predictive value of thyroglobulin changes for the efficacy of thyroid remnant ablation.

The aim of this case-control study was to determine the utility of the evaluation of changes in serum thyroglobulin (Tg) levels before and after 1311 diagnostic total body scan (TBS) in patients with thyroid cancer to predict the efficacy of radioiodine ablation. Among 134 consecutive patients with differentiated thyroid carcinoma (DTC) who had undergone a thyroidectomy and TBS prior to radioiodine ablation, we selected those subjects with no evidence of distant metastases and with two consecutive assessments of Tg before TBS and radioiodine ablation within a period of four weeks. With this selection procedure 27 patients (22 with papillary and five with follicular carcinomas) were included in our evaluation. The ablation therapy was considered successful when the TBS performed one year after treatment did not show any or less than 1% cervical 131I uptake, Tg levels remained below 3 ng/mL, and clinical and instrumental examinations were negative for the presence of relapses. These criteria divided the selected patients into two subsets: patients with successful radioiodine ablation and patients with residual thyroid tissue. The majority of patients with unsuccessful ablation showed an increase in serum Tg levels, while most of the patients with successful ablation showed a steady decrease in Tg concentrations. Statistical analysis evidenced that the increase in Tg levels after TBS was related to unsuccessful ablation (P > or = 0.01). By contrast, the rate of thyroid remnants with 131I uptake did not show any relationship with the outcome of ablation therapy. The group of patients with increasing Tg levels after TBS had a relative risk of 3.3 of unsuccessful ablative therapy compared to the group with stable or decreasing Tg levels. This study supports the concept that by monitoring Tg levels in patients who undergo diagnostic TBS before radioiodine ablation it is possible to obtain useful information about the efficacy of 131I therapy.

Axillary lymph node staging in breast cancer by 2-fluoro-2-deoxy-D-glucose-positron emission tomography: clinical evaluation and alternative management.

BACKGROUND: Surgical removal of axillary lymph node and histologic examination for metastases are used to determine whether adjuvant treatment is necessary for patients with breast cancer. Axillary lymph node dissection (ALND) is a costly procedure associated with various side effects, and 80% or more of patients with tumors of 20 mm or less are lymph node negative and might avoid ALND. In this study, we evaluated whether an alternative, noninvasive method--i.e., positron emission tomography (PET) with 2-[(18)F]fluoro-2-deoxy-D-glucose (FDG)-- could be used to determine axillary lymph node status in patients with breast cancer. METHODS: One hundred sixty-seven consecutive patients with breast cancers of 50 mm or less (range = 5-50 mm; mean = 21 mm) scheduled for complete ALND were studied preoperatively with FDG-PET, and then PET and pathology results from ALND were compared. All statistical tests were two-sided. RESULTS: The overall sensitivity, specificity, and accuracy of lymph node staging with PET were 94.4% (PET detected 68 of 72 patients with axillary involvement; 95% confidence interval [CI] = 86.0% to 98.2%), 86.3% (82 of 95 patients without axillary involvement; 95% CI = 77.8% to 91.9%), and 89.8% (150 of 167 patients with breast cancer; 95% CI = 84.2% to 93.6%), respectively. Positive- and negative-predictive values were 84.0% (68 patients with histologically positive lymph nodes of 81 patients with positive FDG-PET scan; 95% CI = 74.2% to 90.5%) and 95.3% (82 patients with histologically negative lymph nodes of 86 patients with negative FDG-PET scan; 95% CI = 88.2% to 98.5%), respectively. When PET results for axillary metastasis were analyzed by tumor size, the diagnostic accuracy was similar for all groups (86.0%-94.2%), with higher sensitivity for tumors of 21-50 mm (98.0%) and higher specificity for tumors of 10 mm or less (87.8%), and the range was 93.5%-97.3% for negative-predictive values and 54.5%-94.1% for positive-predictive values. Among the 72 patients with axillary involvement, PET detected three or fewer metastatic lymph nodes in 27 (37.5%) patients, about 80% of whom had no clinically palpable axillary lymph nodes. CONCLUSIONS: Noninvasive FDG-PET appears to be an accurate technique to predict axillary status in patients with breast cancer and thus to identify patients who might avoid ALND. These results should be confirmed in large multicenter studies.