Protecting thyroid cancer patients from untoward effects of radioactive iodine treatment

Anaplastic thyroid cancer: How far can we go?

Globally, thyroid cancer accounts for 2 % of all cancer diagnoses, and can be classified as well-differentiated or undifferentiated. Currently, differentiated thyroid carcinomas have good prognoses, and can be treated with a combination of therapies, including surgical thyroidectomy, radioactive iodine therapy and hormone-based therapy. On the other hand, anaplastic thyroid carcinoma, a subtype of undifferentiated thyroid carcinoma characterized by the loss of thyroid-like phenotype and function, does not respond to either radioactive iodine or hormone therapies. In most cases, anaplastic thyroid carcinomas are diagnosed in later stages of the disease, deeming them inoperable, and showing poor response rates to systemic chemotherapy. Recently, treatment courses using multiple-target agents are being explored and clinical trials have shown very promising results, such as overall survival rates, progression-free survival and tumor shrinkage. This review is focused on thyroid carcinomas, with particular focus on anaplastic thyroid carcinoma, exploring its undifferentiated nature. Special interest will be given to the treatment approaches currently available and respective obstacles or drawbacks. Our purpose is to contribute to understand why this malignancy presents low responsiveness to current treatments, while overviewing novel therapies and clinical trials.

Early and late adverse effects of radioiodine for pediatric differentiated thyroid cancer

BACKGROUND

Radioiodine-131 (I131) therapy for differentiated thyroid cancer (DTC) is generally a safe and effective treatment, but it has some potential side effects, which have been well described in adults but less analyzed in children. Our aim was to describe early and late adverse events of radioactive I131 in pediatric patients.

METHODS

All consecutive patients ≤18 years treated for DTC in the period 1980-2015 were retrospectively analyzed for early and late side effects of radioiodine. Early side effects include nausea/emesis, radiation thyroiditis, sialadenitis, dry mouth, and transient bone marrow (BM) suppression. Late complications include permanent salivary gland dysfunction, permanent BM suppression, pulmonary fibrosis, second cancers, and fertility problems.

RESULTS

One hundred five pediatric patients were treated with I131 for DTC in our department for a total amount of 302 radioiodine treatments. In total, 127 early complications were recorded: 44 episodes of nausea/emesis; 30 sialoadenitis, 24 thyroiditis, 18 dry mouth, and 11 transient BM suppression. Early side effects were correlated with the amount of radioactivity administered in any treatment. Twelve children developed ≥1 late complication for a total of 20 complications: two permanent salivary gland dysfunction, four permanent BM suppression, five pulmonary fibrosis, four second malignancies, and five fertility alterations. Late events, except fertility alterations, were correlated with the number of therapies and cumulative activities of I131.

CONCLUSIONS

In conclusion, early side effects of I131 are associated with the amount of administrated activities of each treatment, while the late effects are correlated with the number of treatments and cumulative activities of radioiodine, except for fertility problems.

Risk prediction in children and adults less than 45 years old with papillary thyroid cancer

The incidence of papillary thyroid cancer is increasing faster than any other cancer in young patients. The purpose of this review is to discuss the most recent determinants of risk of recurrence and compromised outcomes in this population. Areas covered: This review discusses the most updated data on patient age, including children and young adults, extent of disease and subsequent dynamic staging over time, molecular markers for disease aggressiveness, adequacy of surgical resection and surgeon volume, and novel therapies for advanced non-resectable disease as predictors of patient outcomes. Expert commentary: Young patients enjoy excellent outcomes, with long-term survivorship, but face higher risks of short-term complications and disease recurrence. Thoughtful evaluation of the extent of disease, tumor features associated with more aggressive behavior, the presence of locoregional or distant metastases, and an understanding of molecular changes in their tumors are important areas of consideration. High-volume surgeons should work collaboratively with endocrinologists, radiologists, and pathologists specializing in thyroid cancer to help patients achieve excellent outcomes. Emerging data challenging the status quo regarding the relative importance of patient age, tumor features, and dynamic risk-adjustment for overall prognosis of these patients will likely impact future care and staging systems.

Management Guidelines for Children with Thyroid Nodules and Differentiated Thyroid Cancer

BACKGROUND

Previous guidelines for the management of thyroid nodules and cancers were geared toward adults. Compared with thyroid neoplasms in adults, however, those in the pediatric population exhibit differences in pathophysiology, clinical presentation, and long-term outcomes. Furthermore, therapy that may be recommended for an adult may not be appropriate for a child who is at low risk for death but at higher risk for long-term harm from overly aggressive treatment. For these reasons, unique guidelines for children and adolescents with thyroid tumors are needed.

METHODS

A task force commissioned by the American Thyroid Association (ATA) developed a series of clinically relevant questions pertaining to the management of children with thyroid nodules and differentiated thyroid cancer (DTC). Using an extensive literature search, primarily focused on studies that included subjects ≤18 years of age, the task force identified and reviewed relevant articles through April 2014. Recommendations were made based upon scientific evidence and expert opinion and were graded using a modified schema from the United States Preventive Services Task Force.

RESULTS

These inaugural guidelines provide recommendations for the evaluation and management of thyroid nodules in children and adolescents, including the role and interpretation of ultrasound, fine-needle aspiration cytology, and the management of benign nodules. Recommendations for the evaluation, treatment, and follow-up of children and adolescents with DTC are outlined and include preoperative staging, surgical management, postoperative staging, the role of radioactive iodine therapy, and goals for thyrotropin suppression. Management algorithms are proposed and separate recommendations for papillary and follicular thyroid cancers are provided.

CONCLUSIONS

In response to our charge as an independent task force appointed by the ATA, we developed recommendations based on scientific evidence and expert opinion for the management of thyroid nodules and DTC in children and adolescents. In our opinion, these represent the current optimal care for children and adolescents with these conditions.

Radioprotective agents for the prevention of side effects induced by radioiodine-131 therapy

Radioiodine 131 (131I) has been used worldwide for the ablation of remnant thyroidal tissue after surgery or as the first-line treatment for Graves’ disease. Although the use of 131I is becoming increasingly prevalent, there is evidence suggesting that this treatment is associated with side effects such as salivary gland dysfunction and an increased risk of leukemia. This article aims to review the potential use of radioprotective agents and the side effects induced by 131I therapy. Several synthetic and natural compounds have been investigated in preclinical and clinical studies. The protective agents reduced the toxicity of 131I, mainly in the salivary glands, and mitigated the genetic damage through different mechanisms. There are limited clinical studies evaluating the use of radioprotective agents in patients undergoing radioiodine therapy. However, lemon candies, lemon juice and sugarless chewing gum have been proposed to be beneficial for minimizing the side effects of radioiodine within the salivary glands.

I-131 SPECT/CT elucidates cryptic findings on planar whole-body scans and can reduce needless therapy with I-131 in post-thyroidectomy thyroid cancer patients

BACKGROUND

Interpreting I-131 whole-body scans (WBSs) after thyroidectomy for thyroid cancer is not simple. There are scans in which interpretation is speculative because of cryptic findings (CF). Complexity is added in scans that are done a week after an ablative or therapeutic dose of I-131 because not only is I-131-labeled thyroxine (T4) distributed throughout the body, but inorganic I-131 that is derived from the de-iodination of T4 may be also detected. We present our observations regarding the analysis of CF on WBS using I-131 single-photon emission computed tomography (SPECT) in fusion with noncontrast computed tomography (CT), referred to here and elsewhere as I-131 SPECT/CT.

METHODS

Forty of 184 WBSs in 38 thyroidectomized thyroid cancer patients were followed up with I-131 SPECT/CTs. The SPECT/CT images were acquired after a tracer dose of I-131 (n=82) or a week after an ablative or therapeutic dose of I-131 (n=102).

RESULTS

Among 184 WBSs, 40 (22%) had CF. In 35 patients the WBS was negative for metastatic disease except for the CF and 5 patients had evidence of thyroid cancer in addition to the CF. There were 49 CF in the planar scans that were localized by SPECT/CT. These were characterized as physiological uptake in gingiva, thymus, gall bladder, menstrual blood, uterine fibroid, recto-sigmoid, colon, and bladder. Also observed was uptake in sites that represented nonthyroidal pathology including dental abscess, hiatal hernia, renal cyst, and struma ovarii. SPECT/CT suggested that 10 of the CF were actually of thyroid origin. In 40 SPECT/CT scans, the images contributed to interpreting the scan. In 15 of 40 patients the SPECT/CT analysis of WBS was performed with tracer doses of I-131 and was important for determining whether to administer ablative I-131 treatment. In another 25 patients, in whom SPECT/CT was performed after ablative or therapeutic doses of 131-I, information regarding the characterization of CF by SPECT/CT was useful in determining if thyroid cancer metastases or thyroid remnants were present.

CONCLUSIONS

I-131 SPECT/CT is a useful tool to characterize atypical or CF on WBS by differentiating thyroid remnant or cancer from physiologic activity or nonthyroid pathology. In the past, uptake on a WBS that was not explicable as physiologic activity was identified as putative or possible thyroid cancer and generally was treated with I-131. Now, by identifying activity in some possible cancer sites as not thyroid cancer, SPECT/CT can reduce inappropriate treatment with I-131. SPECT/CT of WBS performed after ablative doses of 131-I is useful in determining the nature of CF and therefore likely providing prognostic information.

[Outcome of differentiated thyroid cancer after initial treatment]

Incidence of differentiated thyroid cancer has increased in the last two decades. This type of cancer is now being diagnosed at an earlier stage. Treatment strategy has been modified.

AIMS

The goals of this study were to analyze the outcome of differentiated thyroid cancer after initial treatment (surgery and radioiodine ablation) in patients evaluated and followed up in a single centre between l999 and 2009, to compare these results with others as well as to monitor the adoption of international recommendation. 107 patients having T1-T2 differentiated thyroid cancer were studied. Mean follow-up time was 63 months.

RESULTS

After surgery patients were prepared using thyroid hormone withdrawal or recombinant human thyrotropin, then 1.1-3.7 GBq 131-iodine was administered. First year evaluation consisted of ultrasound as well as serum thyrotropin and thyroglobulin (plus thyroglobulin antibody) determinations. Ablation success rate was 83% and the five year survival was 100%. There was not any cancer specific death.

CONCLUSION

In the future somewhat more radical surgery and less remnant ablation is needed with unified follow-up protocol.

Use of radioactive iodine for thyroid cancer

CONTEXT

Substantial uncertainty persists about the indications for radioactive iodine for thyroid cancer. Use of radioactive iodine over time and the correlates of its use remain unknown.

OBJECTIVE

To determine practice patterns, the degree to which hospitals vary in their use of radioactive iodine, and factors that contribute to this variation.

DESIGN, SETTING, AND PATIENTS

Time trend analysis of radioactive iodine use in a cohort of 189,219 patients with well-differentiated thyroid cancer treated at 981 hospitals associated with the US National Cancer Database between 1990 and 2008. We used multilevel analysis to assess the correlates of patient and hospital characteristics on radioactive iodine use in the cohort treated from 2004 to 2008.

MAIN OUTCOME MEASURE

Use of radioactive iodine after total thyroidectomy.

RESULTS

Between 1990 and 2008, across all tumor sizes, there was a significant increase in the proportion of patients with well-differentiated thyroid cancer receiving radioactive iodine (1373/3397 [40.4%] vs 11,539/20,620 [56.0%]; P < .001). Multivariable analysis of patients treated from 2004 to 2008 found that there was a statistical difference in radioactive iodine use between American Joint Committee on Cancer stages I and IV (odds ratio [OR], 0.34; 95% confidence interval [CI], 0.31-0.37) but not between stages II/III and IV (for stage II vs stage IV, OR, 0.97; 95% CI, 0.88-1.07 and for stage III vs stage IV, OR, 1.06; 95% CI, 0.95-1.17). In addition to patient and tumor characteristics, hospital volume was associated with radioactive iodine use. Wide variation in radioactive iodine use existed, and only 21.1% of this variation was accounted for by patient and tumor characteristics. Hospital type and case volume accounted for 17.1% of the variation. After adjusting for available patient, tumor, and hospital characteristics, 29.1% of the variance was attributable to unexplained hospital characteristics.

CONCLUSION

Among patients treated for well-differentiated thyroid cancer at hospitals in the National Cancer Database, there was an increase in the proportion receiving radioactive iodine between 1990 and 2008; much of the variation in use was associated with hospital characteristics.

Single photon emission computed tomography imaging for temporal dynamics of thyroidal and salivary radionuclide accumulation in 17-allyamino-17-demothoxygeldanamycin-treated thyroid cancer mouse model

Selective iodide uptake and prolonged iodine retention in the thyroid is the basis for targeted radioiodine therapy for thyroid cancer patients; however, salivary gland dysfunction is the most frequent nonthyroidal complications. In this study, we have used noninvasive single photon emission computed tomography functional imaging to quantify the temporal dynamics of thyroidal and salivary radioiodine accumulation in mice. At 60  min post radionuclide injection, radionuclide accumulation in the salivary gland was generally higher than that in thyroid due to much larger volume of the salivary gland. However, radionuclide accumulation per anatomic unit in the salivary gland was lower than that in thyroid and was comparable among mice of different age and gender. Differently, radionuclide accumulation per anatomic unit in thyroid varied greatly among mice. The extent of thyroidal radioiodine accumulation stimulated by a single dose of exogenous bovine TSH (bTSH) in triiodothyronine (T₃)-supplemented mice was much less than that in mice received neither bTSH nor T₃ (nontreated mice), suggesting that the duration of elevated serum TSH level is important to maximize thyroidal radioiodine accumulation. Furthermore, the extent and duration of radioiodine accumulation stimulated by bTSH was less in the thyroids of the thyroid-targeted RET/PTC1 (thyroglobulin (Tg)-PTC1) mice bearing thyroid tumors compared with the thyroids in wild-type (WT) mice. Finally, the effect of 17-allyamino-17-demothoxygeldanamycin on increasing thyroidal, but not salivary, radioiodine accumulation was validated in both WT mice and Tg-PTC1 preclinical thyroid cancer mouse model.

Radiopharmacokinetics of radioiodine in the parotid glands after the administration of lemon juice

BACKGROUND

The ability of sialagogues to increase or decrease radiation induced-sialoadenitis and/or xerostomia after therapeutic administration of ¹³¹I is controversial. To evaluate this we measured the radiopharmacokinetics of ¹²³I in the parotid glands (PGs) after its administration of lemon juice (LJ).

METHODS

A retrospective review was performed on all patients who had a salivary gland scan performed before ¹³¹I therapy between July 2008 and April 2009 at the Washington Hospital Center. Two hours after ¹²³I was given orally, dynamic scintigraphy was initiated. Five milliliters of LJ was given 5 minutes later. Then, the patient was imaged for 1 hour (phase 1) at which point the sequence was repeated (phase 2). Twenty-three patients were studied. For each PG, the presence or absence of uptake was assessed, and based on background corrected counts, the mean, range, and standard deviation were determined for multiple radiopharmacokinetic parameters such as (i) percent radioiodine washout, (ii) time from LJ administration to re-accumulation of radioiodine to pre-LJ activity, and (iii) percent reduction in radiation absorbed dose to the PGs if LJ had been re-administered at the time the radioiodine activity re-accumulated to the pre-LJ activity.

RESULTS

The mean  ± one standard deviation and range for percent washout were 84%  ± 18% (35%-100%) and 83%  ±  21% (37%-100%) in phase 1 and 2, respectively. The times from LJ to re-accumulation of the radioiodine to the pre-LJ activity were 21  ± 10 minutes (4-45 minutes) and 40  ± 14 minutes (12-62 minutes) for phase 1 and 2, respectively. The estimated percent reduction in radiation absorbed dose to the PGs following the first and second administration of LJ was 37%  ± 14% (13%-93%) and 47% ± 16% (21%-97%), respectively.

CONCLUSIONS

The washout of radioiodine from the PGs is rapid but transient. Early repeat administration may result in continued and cumulative reduction of radiation absorbed dose in the PGs.

Salivary gland malignancy and radioiodine therapy for thyroid cancer

BACKGROUND

The risk of second primary malignancies in patients with well-differentiated thyroid cancer is of special interest because of the common use of radioactive iodine (RAI) ablation and/or treatment of these patients and the theoretical risk of subsequent nonthyroid malignancies associated with the radiation exposure. This brief report focuses specifically on the occurrence of second primary malignancies of the salivary glands. RAI residency within salivary tissues is known to have both acute and chronic consequences on salivary function, but secondary neoplasia is quite unusual.

SUMMARY

We present a very rare case of a patient with papillary thyroid cancer treated with 600 mCi of RAI, who subsequently developed salivary gland cancer.

CONCLUSIONS

We recommend salivary gland protection to diminish potential side effects after the exposure to radioiodine. On the basis of our experience we suggest administration of sialogogues (such as lemon juice) continuously, every 30-60 minutes for 24 hours, after RAI administration.