Radiation to the Primary Tumor in Metastatic Anaplastic Thyroid Cancer

Anti-Proliferative Effect of Radiotherapy and Implication of Immunotherapy in Anaplastic Thyroid Cancer Cells

Radiotherapy and immunotherapy have shown promising efficacy for the treatment of solid malignancies. Here, we aim to clarify the potential of a combined application of radiotherapy and programmed cell death-ligand 1 (PD-L1) monoclonal antibody atezolizumab in primary anaplastic thyroid cancer (ATC) cells. The radiation caused a significant reduction in cell proliferation, measured by luminescence, and of the number of colonies. The addition of atezolizumab caused a further reduction in cell proliferation of the irradiated ATC cells. However, the combined treatment did not cause either the exposure of the phosphatidylserine or the necrosis, assessed by luminescence/fluorescence. Additionally, a reduction in both uncleaved and cleaved forms of caspases 8 and 3 proteins was detectable in radiated cells. The DNA damage evidenced the over-expression of TP53, CDKN1A and CDKN1B transcripts detected by RT-qPCR and the increase in the protein level of P-γH2AX and the DNA repair deputed kinases. PD-L1 protein level increased in ATC cells after radiation. Radiotherapy caused the reduction in cell viability and an increase of PD-L1-expression, but not apoptotic cell death in ATC cells. The further combination with the immunotherapeutic atezolizumab could increase the efficacy of radiotherapy in terms of reduction in cell proliferation. Further analysis of the involvement of alternative cell death mechanisms is necessary to clarify their cell demise mechanism of action. Their efficacy represents a promising therapy for patients affected by ATC.

Role of surgery to the primary tumor in metastatic anaplastic thyroid carcinoma: pooled analysis and SEER-based study

PURPOSE

Anaplastic thyroid carcinoma (ATC) is an orphan disease with a fatal outcome. Surgery to the primary tumor in metastatic ATC is controversial. Determination of specific surgical techniques may help facilitate local control and, hence, beneficial overall and disease-specific survival.

METHODS

Using individualized patient data derived from our systematic review of literature and our single center study (n = 123), conducting a Surveillance, Epidemiology, and End Results register (SEER)-based study (n = 617) we evaluated surgery, its combination with systemic and local therapies in metastatic ATC.

RESULTS

Pooled cohort study showed surgery (p < 0.001), RT ≥ 30 Gy (p < 0.001), ChT (p < 0.001) and multimodal treatment (p = 0.014) to result in improved OS univariately. In the multivariate analysis, surgery (1.997 [1.162-3.433], p = 0.012) and RT ≥ 30 Gy (1.877 [1.232-2.843], p = 0.012) were independent predictors for OS. In SEER-based study of patients undergoing any tumor-directed treatment (n = 445) total thyroidectomy (p = 0.031), administration of ChT (p = 0.007), RT (p < 0.001), combination of surgery and RT ± ChT (p < 0.001) and multimodal treatment (p < 0.001) correlated with an improved DSS univariately. On the multivariate analysis, debulking surgery was an independent predictor for a worse outcome (HR 0.535, 95%CI 0.332-0.862, p = 0.010), whereas RT administration correlated with a longer DSS (HR 2.316, 95%CI 1.362-3.939, p = 0.002). Among operated patients from SEER register total thyroidectomy (p = 0.031), ChT (p = 0.007), RT (p < 0.001), combination of surgery and RT ± ChT (p < 0.001) and multimodal treatment (p < 0.001) correlated with an improved DSS in the univariate analysis, whereas debulking surgery was inversely correlated with the DSS (p < 0.001). On the multivariate analysis, debulking surgery was an independent predictor for a worse DSS (HR 0.535, 95%CI 0.332-0.862, p = 0.010), whilst RT administration correlated with a longer DSS (HR 2.316, 95%CI 1.362-3.939, p = 0.002).

CONCLUSIONS

Surgery to the primary tumor with the aim of R0/R1 resection, but not debulking, is associated with a significant OS and DSS benefit even in systemically metastasized disease.

Hypoxia in Solid Tumors: How Low Oxygenation Impacts the "Six Rs" of Radiotherapy

Radiotherapy is an important component of cancer treatment, with approximately 50% of all cancer patients receiving radiation therapy during their course of illness. Nevertheless, solid tumors frequently exhibit hypoxic areas, which can hinder therapies efficacy, especially radiotherapy one. Indeed, hypoxia impacts the six parameters governing the radiotherapy response, called the « six Rs of radiation biology » (for Radiosensitivity, Repair, Repopulation, Redistribution, Reoxygenation, and Reactivation of anti-tumor immune response), by inducing pleiotropic cellular adaptions, such as cell metabolism rewiring, epigenetic landscape remodeling, and cell death weakening, with significant clinical repercussions. In this review, according to the six Rs, we detail how hypoxia, and associated mechanisms and pathways, impact the radiotherapy response of solid tumors and the resulting clinical implications. We finally illustrate it in hypoxic endocrine cancers through a focus on anaplastic thyroid carcinomas.