Clinical Thyroidology® for the Public

Summaries for the Public from recent articles in Clinical Thyroidology
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THYROID CANCER
Is lenvatinib better than sorafenib as first-line treatment of thyroid cancer that no longer responds to radioactive iodine therapy?

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BACKGROUND
The usual initial treatment of thyroid cancer includes thyroid surgery. For patients whose cancer has a higher risk of recurrence, surgery is followed by radioactive iodine therapy. The vast majority of patients respond to these treatments. However, when thyroid cancer spreads, often the cancer cells do not respond to radioactive iodine therapy. In those cases, if the cancer progresses, a special type of chemotherapy agent, called tyrosine kinase inhibitors (TKIs), is used as treatment. There are two TKIs approved for use in thyroid cancer, lenvatinib and sorafenib.

In this study, the authors compared the efficacy of these two drugs in patients with progressive thyroid cancer that does not respond to radioactive iodine therapy.

THE FULL ARTICLE TITLE
 Kim M et al 2022 Lenvatinib compared with sorafenib as a first-line treatment for radioactive iodine-refractory, progressive, differentiated thyroid carcinoma: Real-world outcomes in a multicenter retrospective cohort study. Thyroid. Epub 2022 May 17. PMID: 35443825.

SUMMARY OF THE STUDY
The authors studied 136 patients who were seen in six referral hospitals in Korea. The study group included patients with thyroid cancer with progressive cancer not responsive to radioactive iodine therapy as well as patients with poorly differentiated thyroid cancer.

All patients were treated with either sorafenib or lenvatinib. The authors looked at progression free-survival (PFS), which means the time from starting the treatment until the cancer gets worse or progresses, response to treatment assessed by radiological studies, clinical benefit and safety. The average age of the patients was 68 and about 66% were women. Overall 80 patients received sorafenib and 56 patients received lenvatinib.

In average, PFS was 13 months in the sorafenib group and 35 months in the lenvatinib group, meaning, it took longer for cancer to progress on the patients taking lenvatinib as compared to sorafenib. Patients in the lenvatinib group had decreased progression of the disease as compared with patients in the sorafenib group. Patients in both groups reported side effects; however, patients in the lenvatinib group have higher chances of needing dose reductions or interruption of the treatment due to side effects.

WHAT ARE THE IMPLICATIONS OF THIS STUDY?
Both sorafenib and lenvatinib are approved for treatment of thyroid cancer, but direct comparisons of these two drugs are lacking. This study shows that lenvatinib is more effective than sorafenib; however, lenvatinib appeared to have more side effects. More studies are needed to be able to compare “head to head” both drugs in a prospective, randomized fashion.

— Susana Ebner MD

ABBREVIATIONS & DEFINITIONS

Radioactive iodine (RAI): this plays a valuable role in diagnosing and treating thyroid problems since it is taken up only by the thyroid gland. I-131 is the destructive form used to destroy thyroid tissue in the treatment of thyroid cancer and with an overactive thyroid. I-123 is the nondestructive form that does not damage the thyroid and is used in scans to take pictures of the thyroid (Thyroid Scan) or to take pictures of the whole body to look for thyroid cancer (Whole Body Scan).

Cancer recurrence: this occurs when the cancer comes back after an initial treatment that was successful in destroying all detectable cancer at some point.

Tyrosine kinases: proteins that are overactive in many of the pathways that cause cells to be cancerous. Inhibiting these proteins with drugs known as tyrosine kinase inhibitors are effective chemotherapy drugs for cancers, including advanced thyroid cancer.

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