Increased therapeutic effect on medullary thyroid cancer using a combination of radiation and tyrosine kinase inhibitors

Long-term survival outcomes of systemic therapy in patients with isolated and mixed medullary thyroid cancer

Background

Medullary thyroid carcinoma (MTC) is an uncommon thyroid cancer with limited treatment options for advanced disease. A small subset exhibits mixed MTC histology with both medullary and well-differentiated components. We investigated survival outcomes with systemic therapy in isolated versus mixed MTC using a large population-based cohort.

Methods

Patients diagnosed with MTC from 2000 to 2019 were identified in the National Cancer Institute's Surveillance, Epidemiology, and End Results database. The overall and thyroid cancer-specific survivals were compared between isolated (n = 1814) and mixed (n = 113) MTC cohorts. The impact of postoperative systemic therapy on survival was analyzed.

Results

No significant difference in 10-year overall survival was observed between isolated (77.4 %) and mixed (75.2 %) MTC in a cohort of 1927 patients. Median overall survival was similar between isolated (136.9 months) and mixed MTC (129.0 months), p = 0.81. While systemic therapy improved 10-year survival in isolated MTC (83.2 % vs. 76.9 %, p < 0.001), no benefit was seen in mixed MTC (76.4 % vs. 74.2 %, p = 0.82). Multivariate analysis confirmed survival gains with systemic therapy for isolated (HR = 0.763, 95%CI = 0.590-0.987, p = 0.040) but not mixed MTC (HR = 0.909, 95%CI = 0.268-3.079, p = 0.88).

Conclusions

In this large population-based study, no significant survival difference was observed between isolated and mixed MTC. Systemic therapy was associated with improved survival in isolated MTC, but not in the mixed subtype. These findings suggest a differential treatment response that warrants further investigation in prospective studies and may inform histology-tailored management strategies for mixed MTC.

Medullary thyroid carcinoma

PURPOSE OF REVIEW

To summarize recent developments in the diagnosis and management of patients with medullary thyroid cancer (MTC), with a focus on pathogenesis, systemic therapy, and future directions.

RECENT FINDINGS

The addition of mutational analysis to cytological assessment of thyroid nodules has improved the diagnostic accuracy of MTC. The discovery of new genomic alterations and overexpression of certain factors allows for improved prognostication in MTC and provides potentially new therapeutic agents. New data suggest that tumor environment may be more immunogenic than previously thought in a subset of MTCs with identification of a new MTC-specific antigen leading to a revival of investigating immune-based therapy for this disease. The newly approved selective rearranged during transfection (RET0-inhibitors, selpercatinib and pralsetinib, offer promising results, and tolerability for patients with RET-mutated MTC; however, the development of resistance mechanisms may be problematic.

SUMMARY

MTC has witnessed remarkable advancements in recent years. Our new understanding of some of the driver mutations in MTC allows for therapeutics with more tolerable adverse event profiles. However, there is still a need for more effective treatment strategies for subsets of patients without actionable mutations and for those who develop resistance to currently available therapies.