Second malignancies in patients with differentiated thyroid carcinoma treated with low and medium activities of radioactive I-131

Incidentally Detected Metachronous Malignancy in Patients of Papillary Carcinoma of Thyroid Posthigh-Dose Radioiodine Therapy

Thyroid cancer is one of the most common endocrine cancers. The most common histological subtypes are papillary and follicular variants; these are "differentiated thyroid cancers" and are associated with an excellent prognosis. The exact mechanism of thyroid cancer is not known. Several genetic alterations and environmental factors are found to be associated with this cancer. Patients with differentiated thyroid cancer are treated with postoperative radioactive iodine (RAI) therapy to ablate residual thyroid tissue and metastatic micro-foci. It is thought that after RAI, there is an increased risk of secondary malignancies such as lung, renal, and stomach cancer and lymphomas. However, the risk of secondary malignancy is not clear. They may be associated with genetic syndromes, environmental factors, and radiation exposure. The secondary malignancy may be detected incidentally during follow-up or present with signs and symptoms of that malignancy. There is no direct association between second malignancy and radiation exposure in I-131 therapies. We present a case series of five patients treated with high doses of I-131 for the remnant. The patients developed metachronous malignancies later in life.

Risk of second primary lung cancer in patients with thyroid cancer: a meta-analysis based on big population studies

BACKGROUND

Previous studies have revealed that the number of cancer survivors developing a second primary malignancy is increasing, especially among thyroid cancer patients, and lung cancer is still the main cause of cancer death. Therefore, we aimed to investigate the risk of second primary lung cancer (SPLC) in patients with thyroid cancer.

METHODS

We searched the PubMed, Web of Science, Embase, and Scopus databases up to November 24, 2021, for relevant research and merged the standardized incidence ratios (SIRs) and 95% confidence intervals (95% CIs) to evaluate the risk of developing SPLC in patients with thyroid cancer.

RESULTS

Fourteen studies involving 1480,816 cases were included in our meta-analysis. The pooled result demonstrated that thyroid cancer patients may have a higher risk of SPLC than the general population (SIR = 1.21, 95% CI: 1.07-1.36, P < 0.01, I2 = 81%, P < 0.01). Subgroup analysis stratified by sex indicated that female patients may have a markedly higher risk of SPLC than male patients (SIR = 1.65, 95% CI: 1.40-1.94, P < 0.01, I2 = 75%, P < 0.01).

CONCLUSIONS

Thyroid cancer patients are more likely to develop SPLC than the general population, especially women. However, other risk factors must be investigated, and more prospective studies are needed to confirm our results.Registration: International Prospective Register of Systematic Reviews: No. CRD42021285399.

Triple Metachronous Malignancies with Thyroid Involvement: A Brief Overview of Five Case Reports over 20 Years of Institutional Experience

Multiple primary malignant tumors are defined by the development of more than one malignancy in a single patient. These can be subdivided into synchronous or metachronous malignant tumors, depending on their time of appearance, relative to the first malignancy. Triple primary malignancies are a relatively rare occurrence in day-to-day practice and triple synchronous or metachronous carcinomas involving a thyroid localization are even less common. In this case series, we report our 20-year experience in diagnosing and managing five patients with triple malignant tumors with thyroid involvement.

Radioactive Iodine Ablation Decrease Recurrences in Papillary Thyroid Microcarcinoma with Lateral Lymph Node Metastasis in Chinese Patients

Introduction

We aimed to carry out a retrospective study from a single institution to determine whether radioactive iodine (RAI) ablation decreases the risk of recurrence of papillary thyroid microcarcinoma (PTMC) patients that presented with lateral lymph node metastasis (LLNM).

Methods

We retrospectively analyzed a total of 6361 consecutive PTMC patients who initially underwent surgery for the treatment of thyroid carcinoma at the First Hospital of Jilin University, between January 2005 and February 2015. Altogether, 137 patients with PTMC with LLNM have been enrolled in our study.

Results

The disease-free survival period was significantly shorter for the RAI (−) patients than for the RAI (+) patients (p = 0.0074 by the log-rank test). The disease-free survival rates at 5 and 10 years were 93.02 and 87.5%, respectively, in the RAI (−) group and 100 and 96.81%, respectively, in the RAI (+) group. CLNM ratio and LLNM ratio were factors identified for multivariate analysis by Cox’s proportional hazards method yielding risk ratios of 7.281 [CI 1.804–17.554; p = 0.010] and 1.157 [CI 1.0125–9.381; p = 0.048] in the RAI (−) group.

Conclusion

Taken together, RAI may be beneficial for PTMC with LLNM, especially when CLNM ratio or LLNM ratio was greater than 0.5.