New dimensions in radiotherapy are paving the way to strategize pleural mesothelioma treatment. Changes in the fractionation of radiation dosage, use of Stereotactic Body Radiation Therapy- SBRT as salvage therapy and combining radiotherapy with immunotherapy are few of the most hopeful strategies to treat pleural mesothelioma.

International mesothelioma interest group - iMig conduct a meeting in which scientists from all over the world present their work in the field of mesothelioma. iMig is an independent international organization of scientists who work together to understand, treat, and prevent mesothelioma.

In the review, titled "The role of radiation treatment in pleural mesothelioma: Highlights of the 14th International Conference of the International mesothelioma interest group" the researchers covered the advanced researches presented at the International Conference.

The authors of the review have pointed out the significance of radiotherapy in treating pleural mesothelioma.

Lung Cancer published this review on 31st March 2019.

Next, the 15th International conference will be held in 2020 in Brisbane, Australia.

All studies exhibited at the conference showed remarkable potential in radiotherapy for treating mesothelioma. Following is the gist of the most significant studies of all.

Radiotherapy can Reduce the Tumor Size and can Strengthen Immunity

Australian researchers from the University of Western Australia, National Center for Asbestos Related Diseases (NCARD) studied the significance of radiotherapy on the short to medium tumors and on larger tumors in mesothelioma mice models.

The study submitted in the conference titled, "Understanding the Immune Response to Radiotherapy in a Dual Tumour model of mesothelioma."

The intensities of radiation doses include 9, 18, and 27Gy.

The researchers observed shrinkage in small/ medium tumors, whereas the treated tumor remained the same with the radiation dose of 18 and 27Gy.

Larger tumors also reduced in size after some time with 18 and 27Gy.

The researchers concluded that varying fractions of radiation could improve the anti-tumor activity in mesothelioma treatment, saying

"Our data demonstrate a fractionation dose required to observe an anti-tumor response in our mesothelioma models. We observed changes in the immune response to radiotherapy in the microtumor environment that could lead to potential adjunctive immune modulation therapy techniques to increase the antitumor effect of this treatment modality in the future."

Moreover, the researchers also studied the combined effect of radiotherapy and checkpoint blockade immunotherapy to treat secondary tumors. Checkpoint blockade immunotherapy is considered to be effective in treating pleural mesothelioma when combined with chemotherapy. Anti-PD-1 immunotherapy is bringing positive results in this regard.

The authors of the review article stated the final results of the Australian research as,

"Finally, preliminary experiments indicated that localized radiotherapy increased the expression of T cell activation and checkpoint markers PD-1, OX40, and TIM-3 on TILs in irradiated, but not in non-irradiated tumors in individual mice."

Stereotactic body radiation therapy- SBRT to Treat Recurring Pleural Mesothelioma

Combinations of different therapeutic approaches are increasing the overall survival of malignant pleural mesothelioma. For example, five years total survival time of 50% of the patients who received HIPEC (Hyperthermic intraperitoneal chemotherapy) and CRS (Cytoreductive surgery), and chemotherapy after complete removal of the mesothelioma tumor surgically.

However, the primary issue is that the tumor regenerates after some time.

The recurrence of mesothelioma tumors can be at the primary site, or it can be in other parts of the body as well. This sort of tumor recurrence is called oligometastases.

In Oligometastases pleural mesothelioma, the tumor cells travel from the primary position to one or two other areas of the body, forming new small metastatic tumors.

Researchers from the University Hospital Zurich studied the Stereotactic Body Radiation Therapy as the salvage therapy to find out ways for the treatment of oligometastasised pleural mesothelioma.

Patients who are suffering from malignant mesothelioma that can recur receive salvage radiotherapy, after a specific period of initial treatment.

The researchers submitted this study under the title, "Stereotactic body radiation therapy as Salvage Therapy for Oligometastasized Pleural Mesothelioma after multimodal therapy."

Stereotactic Body Radiation Therapy- SBRT can reasonably increase the overall survival time and decrease local tumor along with acceptable toxicities in lung cancer.

Stereotactic Body Radiation Therapy resulted in a significant option for the treatment of recurrent pleural mesothelioma. The authors who covered the conference explained the results of the research as,

"SBRT is a safe and locally effective treatment option for recurrent MPM. SBRT provided a very encouraging treated metastases control of 94% at 12 months."

This radiation therapy effectively controlled tumor progression.

"Overall, in selected patients with localized and low tumor burden, SBRT may be a promising local ablative therapy to provide effective local control in a short overall treatment time to delay systemic therapy until further disease progression."

Optimal Dose of Radiotherapy to Control Pain in Malignant Pleural Mesothelioma Patients

Researchers from different cancer institutes of the United Kingdom are studying the pain associated with varying doses of radiation therapy. This study aims to find out the optimal dose of radiation and its further fractionation (a division of large dose of radiation into smaller ones given at frequent intervals).

The study titled, "SYSTEMS-2: a phase II Randomized Study of Radiotherapy Dose Escalation for Pain Control in Malignant Pleural Mesothelioma."

Other than observing the pain at the radiotherapy site, the study will also tell the toxic effects of radiotherapy, change in the quality of life of the patients, overall survival time, and other radiological responses. These results will be obtained between 5th and 9th week of radiotherapy.

This study is still open in ten UK centers, and further ten sites will set up.

Researchers of the study concluded that the resulting data would completely describe the effect of radiotherapy on the mesothelioma patient saying,

"Results will inform the optimal dose and fractionation of palliative radiotherapy in MPM. Radiological data will enable further characterization of radiation responses and their correlations with clinical outcomes. Biomarker studies of radiotherapy response could facilitate the prospective identification of patients who may benefit from radiotherapy."

The next conference will further shed light on the development of Radiotherapy for the benefit of mesothelioma patients.

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