Four aspects make this case unusual. First, the length of time between the diagnosis and relapse, 40 years, was remarkable. Ordinarily, the prognosis for the patient's original tumor type, follicular thyroid cancer, is excellent; however, recurrence with an undifferentiated or anaplastic component has a dismal outcome. Anaplastic thyroid cancer is a rare, aggressive cancer accounting for 1%-2% of all thyroid cancer, with a median survival of approximately 3 months. Despite reports of a dismal outcome, several years later, the patient in this case report is currently receiving treatment with pembrolizumab.
Second, the type of recurrence is unusual. Usually, this cancer is localized to the thyroid gland and neck nodes; however, diffuse metastatic spread to bones, central nervous system, and lymph nodes can happen. This presentation of recurrence at a distant site without any evidence of primary tumor is unusual.
Third, the patient's responses, albeit limited, to new molecular therapies are interesting and promising. Lenvatinib is a multi-TKI that targets vascular endothelial growth factor receptors, fibroblast growth factor receptors, platelet-derived growth factor receptor alpha, and the RET and KIT proto-oncogene receptor tyrosine kinase.[2,3] In a recent study, lenvatinib was associated with median overall survival of 4.2 months, compared with 2 months in the palliative care group. In addition, lenvatinib also resulted in a reduction in tumor size ≥ 30% in 31.3% of the patients (n = 5), which was considered to be a clinical partial response.
NTRK inhibitors are approved for tumors with NTRK fusion. The patient responded to chemotherapy, lenvatinib, and larotrectinib, each given sequentially. He had response for approximately 8-9 months with each successive line of therapy, which was better than what would be expected without treatment, as predicted by early studies. Agents such as pembrolizumab have shown to be efficacious in this tumor type.[6,7] He is currently on the programmed death ligand 1 inhibitor pembrolizumab and continues to have ongoing response. Although his responses were brief, they are encouraging, and combination treatments are being tested in ongoing clinical trials.
Fourth, the typing of tumor to search for targetable mutations is a new direction in the field of oncology treatment. Precision oncology has broadened the therapeutic horizon for patients with cancer. Although no targetable mutations were identified in this patient's tumor, it remains a promising route to determine which drugs may work and which ones probably would not.
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Cite this: Meera Mohan, Paulette Mehta. My Strangest Case: The Man With a Heavy Tongue - Medscape - Aug 04, 2020.