Lung metastases in patients with differentiated thyroid carcinoma and evaluation of response to radioiodine therapy

The association between the interval of radioiodine treatment and treatment response, and side effects in patients with lung metastases from differentiated thyroid cancer

Objective

Repeat radioiodine (RAI) treatment has been widely implemented for RAI-avid lung metastases and is clinically effective for lung metastatic differentiated thyroid cancer (DTC). We aim to investigate the association between the interval of RAI treatment and short-term response, and the side effects in patients with lung metastases from DTC and to identify predictors for non-effective response to the next RAI treatment.

Methods

A total of 282 course pairs from 91 patients were established and categorized into two groups by the interval of neighboring RAI treatment (<12 and ≥12 months), and the characteristics and treatment response between the two groups were compared. Multivariate logistic regression was used to identify predictors associated with treatment response. The side effects in the former course and the latter course were compared while taking into account the interval.

Results

No significant difference was found between the two groups in treatment response in the latter course (p > 0.05). In the multivariate analysis, age ≥ 55 years (OR = 7.29, 95% CI = 1.66-33.35, p = 0.008), follicular thyroid cancer (OR = 5.00, 95% CI = 1.23-22.18, p = 0.027), and a second RAI treatment as the former course (OR = 4.77, 95% CI = 1.42-18.61, p = 0.016) were significantly associated with a non-effective response. There was no significant difference in the side effects in the former and latter courses between the two groups (p > 0.05).

Conclusion

The interval of RAI treatment does not affect short-term response and side effects of DTC patients with RAI-avid lung metastases. It was feasible to defer repeat evaluation and treatment with an interval of at least 12 months to obtain an effective response and reduce the risk of side effects.

Efficacy of radioiodine therapy for treating 20 patients with pulmonary metastases from differentiated thyroid cancer and a meta-analysis of the current literature

BACKGROUND

Radioiodine therapy (RAI) after total or near-total thyroidectomy is a recommended treatment for patients with pulmonary metastasis from differentiated thyroid cancer (DTC). However, the total effective rate of iodine-131 therapy remains controversial. This study aimed to determine the efficacy of RAI for treating patients with pulmonary metastasis from DTC, and to identify independent predictors of its efficacy.

METHODS

We conducted a retrospective study to evaluate 20 patients with pulmonary metastasis from DTC who underwent RAI at our center at first and performed a meta-analysis to evaluate relevant literature regarding the overall efficacy of RAI and subgroup-specific efficacies subsequently.

RESULTS

The efficacy rate at our center was 40%, and no significant differences were observed according to sex, age, pathological type, metastasis state, or interval between the initial RAI and final surgery. The meta-analysis revealed that the pooled overall efficacy rate was 58%, and significant differences were observed when we compared pulmonary metastasis versus pulmonary and other distant metastasis, age of < 40 years versus age of ≥ 40 years, papillary thyroid cancer versus follicular thyroid cancer and male patients versus female patients.

CONCLUSIONS

These results suggest that RAI is an effective treatment for patients with pulmonary metastasis from DTC after surgical treatment. The efficacy of RAI was significantly predicted by the presence of papillary thyroid cancer, age of < 40 years, the absence of non-lung distant metastasis and female patients.

Therapeutic response and long-term outcome of differentiated thyroid cancer with pulmonary metastases treated by radioiodine therapy

Objective

To explore the therapeutic response (TR) and long-term outcomes of iodine-131 (I-131) treatment for patients with differentiated thyroid cancer and pulmonary metastases (DTC+PM), as well as the association between the assessment of TR and long-term outcomes.

Methods

This retrospective study comprised 151 DTC+PM patients. TR was evaluated by changes in serum levels of thyroglobulin, anatomic imaging and iodine uptake in pulmonary nodules; logistic regression was applied to identify predictors. Overall survival (OS) was calculated using the Kaplan–Meier method and predictive factors of outcome by multivariate analyses.

Results

After I-131 treatment, 17 patients achieved a complete response, 71 a partial response, and 63 no response. Age, pulmonary nodule size, iodine-concentration within PM, extra-PM, frequency and cumulative dose of I-131 treatment were significant for TR. OS was 72.2% at 5, 55.2% at 10 and 51.3% at 15 years. After adjustment for other factors, age, pulmonary nodule size, extra-PM, frequency and cumulative dose of I-131 treatment were significant. A significant difference of survival rate in patients with different TR group was observed.

Conclusions

There was a supportive response and prognosis for I-131 treatment upon DTC+PM patients. Older patients and those with non-I-131-avid PM were more likely to have no response to I-131 treatment, and greater benefits could be achieved by patients who complete treatment. Long-term outcome was better in patients with age <45 years, pulmonary nodule size <2 cm, without extra-PM, and the frequency of iodine treatment ≥5 times. The predictive power of the TR on long-term prognosis was favorable.

Difference of clinical and radiological characteristics according to radioiodine avidity in pulmonary metastases of differentiated thyroid cancer

PURPOSE

To evaluate differences in clinical, radiological and laboratory findings between pulmonary metastasis with and without radioiodine avidity in thyroidectomized differentiated thyroid cancer (DTC) patients with pulmonary metastasis who underwent high-dose I-131 treatment.

METHODS

A total of 105 DTC patients with pulmonary metastasis (age, 48.7 ± 16.8 years; women/men, 78/27) were included. Clinical characteristics, chest computed tomography (CT), F-18 fluorodeoxyglucose positron emission tomography (F-18 FDG PET)/CT and thyroid-stimulating hormone (TSH)-stimulated serum thyroglobulin (s-Tg) level were compared between patients with and without radioiodine uptake in metastatic lung lesions. The response to I-131 treatment was evaluated with follow-up study.

RESULTS

Eighty-nine patients (84.8 %, whole-body scan positive [WBSP] group) showed radioiodine uptake at pulmonary metastasis on post I-131 treatment whole-body scan (WBS) and 16 patients (15.2 %, WBS negative [WBSN] group) did not show uptake at pulmonary lesions on the WBS. Ninety percent and 87 % of the WBSP group had visible metastatic lesions on CT and F-18 FDG PET/CT; however, all of the patients in the WBSN group showed lesions on CT and F-18 FDG PET/CT. In seven (6.7 %) of 105 patients, CT and F-18 FDG PET/CT could not detect pulmonary lesions, which were diagnosed by post I-131 treatment WBS. Complete disease remission was achieved in six (5.7 %) patients and all of them were in the WBSP group.

CONCLUSIONS

Metastatic lesion was not visualized on chest CT or F-18 FDG PET/CT in 6.7 % of DTC patients with pulmonary metastasis and the lesion was visualized only on post I-131 treatment WBS. Complete remission was achieved in 5.7 % of DTC patients with pulmonary metastasis and the cured metastases were non-visualizing or micronodular lesions on chest CT and demonstrated radioiodine avidity on post I-131 treatment WBS.