Analysis of activity uptake, effective half-life and time-integrated activity for low- and high-risk papillary thyroid cancer patients treated with 1.11 GBq and 3.7 GBq of 131I-NaI respectively

The role of BRAF V600E mutation in post-surgical 131I therapy in papillary thyroid carcinoma: a study based on SPECT-CT uptake analysis

BACKGROUND

The BRAF V600E mutation (BRAF mut) in papillary thyroid cancer (PTC) has been associated with poor response to therapy with ¹³¹I in patients with metastases but the results in postsurgical treatment are controversial. Our main objective is to investigate the impact of the mutation on the biokinetics of the administered ¹³¹I therapy after surgery.

METHODS

A prospective study was designed, from July 2015 to January 2018 which included patients with PTC receiving ¹³¹I therapy after surgical treatment. To study the biokinetics of the radioiodine in postoperative thyroid remnants, SPECT-CT images were acquired so as to obtain the following variables: percentage of remnant uptake at 2 and 7 days post-administration, effective half-life and time-integrated activity coefficient. All of them were compared depending on the mutational diagnosis and other clinical features and pathological variables.

RESULTS

Sixty-one patients, and in total 103 thyroid remnants, were included. About 59% of patients were BRAF mutated. The mutation was associated with classic variant (88.5% vs. 11.5%; P=0.0001), desmoplastic reaction (85.7% vs. 14.3%; P=0.002), smaller tumor size (1.5 vs. 2.1 cm; P=0.024), nodal disease (3.3 vs. 1; P=0.001) and advanced stages (76.9% vs. 23%; P=0.014). The BRAFmut group had a lower percentage of ¹³¹I uptake at 2 days (0.17% vs. 0.47%; P=0.001) and at 7 days (0.02% vs. 0.1%; P=0.013); and a lower time-integrated activity coefficient (0.05h vs. 0.17 h; P=0.002). In univariate analysis, in addition to the mutation, the histological variant was significant but only for time-integrated activity coefficient (P=0.04). In multivariate analysis, only mutation determined the 2-day uptake (P<0.001) and the time-integrated activity coefficient (P<0.001).

CONCLUSIONS

The BRAF V600E mutation is associated with lower ¹³¹I uptake in thyroid remnants. Furthermore, it is an independent factor that decreases the effect of post-surgical ¹³¹I therapy, and therefore, it could be used as a potential tool to optimize the treatment of PTC.

The osteopontin expression and microvascular density in thyroid cancer, comparison of CT and ultrasound in diagnosis of thyroid cancer and correlations of CT features and thyroid cancer

BACKGROUND

The aim of this study was to explore the osteopontin expression and microvascular density in thyroid cancer, compare computed tomography (CT) and ultrasound in diagnosis of thyroid cancer and investigate the correlations of CT Features and thyroid cancer.

METHODS

A total of 80 patients with thyroid masses admitted to our hospital from April 2017 to August 2019 were selected, of which there were 40 with benign tumor and 40 with malignant tumor. All patients with thyroid cancer confirmed by pathological tissue biopsy were examined by ultrasound (ultrasound group) and CT (CT group). The expression of osteopontin was detected by PCR while microvascular density was tested by immunohistochemistry. Then univariate analysis and multivariate logistic regression analysis of risk factors were carried out for CT imaging diagnosis of thyroid cancer.

RESULTS

The levels of osteopontin and microvascular density in malignant group were significantly higher than those in benign group. The incidence rates of unclear boundary and peripheral lymph node enlargement in CT group were remarkably higher than those in ultrasound group. The diagnostic rate of masses ≥1 cm in diameter was notably higher than that of masses <1 cm in diameter in thyroid cancer patients in CT group and ultrasound group (P<0.05). In addition, the diagnostic rates of follicular carcinoma and papillary carcinoma were higher, whereas those of medullary carcinoma and undifferentiated carcinoma were lower in CT group and ultrasound group. There was no significant difference in the accuracy of thyroid cancer diagnosis between CT group and ultrasound group. Moreover, diameter ≥1 cm, irregular shape, unclear boundary, calcified foci, uneven density/echo and peripheral lymph node enlargement were related risk factors for the CT imaging diagnosis of thyroid cancer, in which irregular shape, unclear boundary, calcified foci and uneven density/echo were independent risk factors for the CT imaging diagnosis of thyroid cancer.

CONCLUSIONS

The levels of osteopontin and microvascular density were increased in thyroid cancer. CT examination may be of higher diagnostic value in diagnosis of thyroid cancer compared with ultrasound. Irregular shape, unclear boundary, calcified foci, and uneven density/echo were independent risk factors for the CT imaging diagnosis of thyroid cancer.

Analysis of Residence Time, Effective Half-Life, and Internal Dosimetry Before Radioiodine Therapy

Radioiodine therapy has been widely used for ablation of remnant tissue after surgical treatment of differentiated thyroid carcinoma (DTC). Internal dosimetry provides a new approach to choosing the administered activity-an approach that considers the distribution and retention of 131I individually per patient. This study used clinical techniques of internal dosimetry to assess the accumulated activity, internal bone marrow dosimetry, and effective half-life in patients undergoing treatment for DTC. Methods: This was a quantitative, retrospective study analyzing diagnostic documents and images. The internal dosimetry method calculated the dose absorbed by the bone marrow per administered activity of 131I. Calculation of the absorbed dose took into account the accumulated activity, which was obtained through measurements of whole-body images acquired at 4 intervals over 5 d. Results: The median dose absorbed by the bone marrow per administered activity was 0.117 mGy/MBq (range, 0.043-0.152 mGy/MBq). The median whole-body residence time was 22.0 h (range, 12.6-39.4 h). The median effective half-life was 15.6 h (range, 7.6-28.2 h). Conclusion: Internal dosimetry provides information relevant to safe dose limits for DTC radioiodine therapy, especially in advanced cases of the disease for which greater activities may be necessary.

Dependency of the remnant 131I-NaI biokinetics on the administered activity in patients with differentiated thyroid cancer

PURPOSE

To study the dependency of the effective half-life on the administered activity and the correlation between the time-integrated activity and the remnant uptake at 2d and 7d in patients treated for DTC with 1.11 GBq, 3.7 GBq or 5.55 GBq of ¹³¹I-NaI.

METHODS

Ninety-two patients undergoing total thyroidectomy and lymph node removal were included. If cancer had not spread to lymph nodes, patients received 1.11 GBq of ¹³¹I-NaI when the lesion maximal diameter was smaller than 4 cm, and 3.7 GBq for bigger sizes. If cancer had spread to lymph nodes patients received 5.55 GBq. There were 30, 49 and 13 patients respectively treated with 1.11 GBq(Group 1), 3.7 GBq(Group 2) and 5.55 GBq(Group 3). Two SPECT/CT scans were performed at 2d and 7d after radioiodine administration for each patient to determine the thyroid remnant activities and effective half-lives of the radioiodine.

RESULTS

Statistical analysis showed significant differences (p < 0.05) in the effective half-life among patients treated with 1.11 GBq, 3.7 GBq and 5.55 GBq. A high positive correlation (ρ > 0.95) was found between the time-integrated activity and the remnant activity at 2d for the three groups of patients.

CONCLUSIONS

There were significant differences in the effective half-life of the radioiodine in remnants of patients treated with activities of 1.11 GBq, 3.7 GBq or 5.55 GBq. The high positive linear correlation found between the time-integrated activity and the remnant activity at 2d for the three groups of patients indicate that the time-integrated activity could be estimated from one time-point.

Managing radioiodine refractory thyroid cancer: the role of dosimetry and redifferentiation on subsequent I-131 therapy

Poor responses to iodine-131 (I-131) therapy can relate to either low iodine uptake and retention in thyroid cancer cells or to increased radioresistance. Both mechanisms are currently termed radioactive iodine (RAI)-refractory (RAI-R) thyroid cancer but the first reflects unsuitability for I-131 therapy that can be evaluated in advance of treatment, whereas the other can only be identified post hoc. Management of both represents a considerable challenge in clinical practice as failure of I-131 therapy, the most effective treatment of metastatic thyroid cancer, is associated with a poor overall prognosis. The development of targeted therapies has shown substantial promise in the treatment of RAI-R thyroid cancer in progressive patients. Recent studies show that selective tyrosine kinase inhibitors (TKIs) targeting B-type rapidly accelerated fibrosarcoma kinase (BRAF) and mitogen-activated protein kinase (MEK) can be used as redifferentiation agents to re-induce RAI uptake, thereby (re)enabling I-131 therapy. The use of dosimetry prior- and post-TKI treatment can assist in quantifying RAI uptake and improve identification of patients that will benefit from I-131 therapy. It also potentially offers the prospect of calculating individualized therapeutic administered activities to enhance efficacy and limit toxicity. In this review, we present an overview of the regulation of RAI uptake and clinically investigated redifferentiation agents, both reimbursed and in experimental setting, that induce renewed RAI uptake. We describe the role of dosimetry in redifferentiation and subsequent I-131 therapy in RAI-R thyroid cancer, explain different dosimetry approaches and discuss limitations and considerations in the field.

Randomised comparison of 1.1 GBq and 3.7 GBq radioiodine to ablate the thyroid in the treatment of low-risk thyroid cancer: a 13-year follow-up

Purpose: The optimal activity of radioiodine (I-131) administered for ablation therapy in papillary and follicular thyroid cancer after thyroidectomy remains unknown in a long-term (> 10 year) follow-up. Some, shorter follow-up studies suggest that activities 1.1 GBq and 3.7 GBq are equally effective. We evaluated the long-term outcomes after radioiodine treatment to extend current knowledge about the optimal ablative dose of I-131.Methods: One hundred and sixty consecutive adult patients (129 females, 31 males; mean age 46 ± 14 y, range 18-89 y) diagnosed with histologically confirmed differentiated thyroid cancer, were randomised in a prospective, phase III, open-label, single-centre study, to receive either 1.1 GBq or 3.7 GBq of I-131 after thyroidectomy. At randomisation, patients were stratified according to the histologically verified cervical lymph node status and were prepared for ablation using thyroid hormone withdrawal. No uptake in the whole-body scan with I-131 and serum thyroglobulin concentration less than 1 ng/mL at 4-8 months after treatment was considered successful ablation.Results: Median follow-up time was 13.0 years (mean 11.0 ± 4.8 y; range 0.3-17.1 y). Altogether 81 patients received 1.1 GBq with successful ablation in 45 (56%) patients. In the original study, thirty-six patients (44%) needed one or more extra administrations to replete the ablation. Of these, 4 (8.9%) and 5 (14%) patients relapsed during the follow-up, respectively. Of the 79 patients treated with 3.7 GBq 45 (57%) had successful ablation after one administration of radioiodine and 34 (43%) needed several treatments. Of these, 2 (4.4%) and 9 (26.5%) patients relapsed, respectively. The groups did not differ in the proportion of patients relapsing (p = .591).Conclusion: During follow-up of median 13 years, 3.7 GBq is not superior to 1.1 GBq in the radioiodine treatment after thyroidectomy in papillary and follicular thyroid cancer.