Immunotherapy for endocrine tumours: a clinician's perspective

Immunotherapy has revolutionised the treatment of oncological patients, but its application in various endocrine tumours is rather limited and is mainly used when conventional therapies have failed. Immune checkpoint inhibitors (ICIs) have been employed in progressive adrenocortical carcinoma, primarily utilizing the anti-PD-L1 agent pembrolizumab, obtaining overall response rates ranging between 14% and 23%. In contrast, the response rate in phaeochromocytoma/paraganglioma was substantially less at 9%, considering the small number of patients treated. Similarly, the response rate in advanced differentiated thyroid carcinomas treated with pembrolizumab was also low at 9%, although the combination of ICIs with tyrosine kinase inhibitors showed higher efficacy. Low response rates to ICIs have also been observed in progressive medullary thyroid cancer, except in tumours with a high mutation burden (TMB). Pembrolizumab or spartalizumab can be utilized in patients with high TMB anaplastic thyroid cancer, obtaining better response rates, particularly in patients with high PD-L1 expression. Immunotherapy has also been used in a few cases of parathyroid carcinoma, showing limited antitumour effect. Pituitary carcinomas may exhibit a more favourable response to ICIs compared to aggressive pituitary tumours, particularly corticotroph tumours. Patients with advanced neuroendocrine tumours achieve an overall response rate of 15%, which varies according to the primary tumour site of origin, degree of differentiation, and therapeutic regimen utilised. Future research is needed to evaluate the potential role of immunohistochemical biomarkers, such as programmed death 1/programmed death ligand 1 and TMB, as predictors for the response to immunotherapy. Furthermore, randomised prospective studies could provide more robust data on the efficacy and side effects of ICIs.

[Skull base metastasis from differentiated thyroid carcinoma: 3 cases report and review of literature]

Skull base metastasis from differentiated thyroid carcinoma (DTC), including papillary and follicular thyroid carcinoma, is a rare manifestation and easily misdiagnosed. In this study, we reported three cases whose initial clinical presentation was skull base metastasis complaints with the presence of silent primary sites. Based on the thyroid ultrasound and histopathology (identifying skull base and primary thyroid tumor), the final diagnoses of DTC metastasis to skull base were confirmed. Two patients underwent removal of metastasizing tumors in the skull base and primary thyroid cancer, and have respectively survived 58 months and 4 months since then. Another patient underwent tumor removal of the metastasizing skull base carcinoma leaving the primary lesion intact. However, the patient died of recurrent carcinoma after 18 months. We compared the diagnosis and treatment processes of three patients with DTC metastasis to skull base, and referenced the reported cases in the literature. In conclusion, DTC metastasis to skull base is a rare occurrence and hence easy to be misdiagnosed as primary skull base carcinoma. Clinical records, imaging tests, histopathology and immunohistochemistry are mandatory for differential diagnosis and final diagnosis. Surgical resection of both the primary and metastatic lesions is the recommended treatment. In cases where tumors are removed completely via surgery, no further treatment is necessary postoperatively when meticulously following up is in place. However, in cases where tumors are postoperative residual, radiation therapy after surgery is a feasible option.