Purpose Synchronous bilateral irradiation of both mammary glands and chest wall is a challenging task due to technical difficulties and limited evidence supporting an optimal technique to improve treatment outcomes. We studied and compared the dosimetry data of three radiotherapy techniques to select the most optimal one. Methods We compared three-dimensional conformal radiation treatment (3D CRT), intensity-modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT) during irradiation of synchronous bilateral breast cancer in nine patients followed by examination of dose distribution to the cardiac conduction system (SA node, AV node and Bundle of His), myocardium, lungs, left anterior descending artery (LADA) and right coronary artery (RCA) . Results VMAT is the most sparing technique for SBBC treatment. Even though doses to the SA node, AV node and Bundle of His were higher with VMAT (Dmean were 3.75 ± 0.62, 2.58 ± 0.83 and 3.03 ± 1.18 Gy respectively) compared with 3D CRT (Dmean were 2.61 ± 0.66, 1.52 ± 0.38 and 1.88 ± 0.70 Gy respectively), this difference is statistically insignificant. Doses to the right and left lung (average Dmean = 12.65 ± 3.20 Gy, V20Gy = 24.12 ± 6.25%), myocardium (Dmean = 5.33 ± 1.51 Gy, V10Gy = 9.80 ± 3.83%, V20Gy = 7.19 ± 3.15%, V25Gy = 6.20 ± 2.93%), and LADA (Dmean = 10.04 ± 4.92 Gy, V20Gy = 18.17 ± 13.24% and V25Gy = 15.41 ± 12.19%) were highest with 3D CRT. The highest  Dmean in the cardiac conduction system (5.30 ± 2.23, 3.15 ± 1.61 and 3.89 ± 1.85 Gy respectively) was observed with IMRT, and a similar effect was noted in RCA (Dmean = 7.48 ± 2.11 Gy). Conclusion VMAT is the optimal and satisfactory radiation therapy technique for sparing organs at risk (OARs). With VMAT, a lower Dmean value was noted in the myocardium, LADA, and lungs. The use of 3D CRT significantly increases the dose of radiation reaching the lungs, myocardium, and LADA, which can subsequently cause cardiovascular and lung complications, but not in the cardiac conduction system.

Purpose: Synchronous bilateral irradiation of both the mammary glands and the chest wall is a challenging task due to technical difficulties and limited evidence supporting an optimal technique for positive treatment outcomes. We analyzed and compared the dosimetry data of three radiotherapy techniques and selected the most effective one.Methods: Three-dimensional conformal radiation treatment (3DCRT), intensity-modulated radiation therapy (IMRT), and volumetric-modulated arc therapy (VMAT) were compared during the irradiation of synchronous bilateral breast cancer. This was followed by examination of the dose distribution to the target organs (myocardium, left anterior descending artery (LADA), right coronary artery (RCA), and lungs in nine patients.Results: Dose distribution in the lungs was optimal using VMAT, while IMRT was less effective. Doses in the lungs, myocardium, and LADA were highest with 3DCRT. The highest mean dose in the myocardium was observed with IMRT, and a similar effect was noted with RCA. VMAT is the most sparing technique for the myocardium and LADA, despite the RCA dose being slightly higher when compared with that of 3DCRT.Conclusion: We concluded that VMAT is a very effective and satisfactory radiation technique for sparing critical organs. With VMAT, regardless of the volume and side of irradiation, a lower mean dose (Dmean) value was noted in organs at risk such as the myocardium, LADA, and lungs, but not the cardiac conduction system. The use of 3DCRT significantly increases the dose of ionizing radiation reaching the lungs, myocardium, and LADA, which can subsequently cause cardiovascular and lung complications.

Adenoid cystic carcinoma (ACC) of the lacrimal gland is a rare tumor. In addition, considering the lack of data on large groups of patients there is no standard of care to treat patients with multiple meningeal metastases of ACC. A two-year analysis of the course of the disease in a patient with synchronous oligometastatic ACC of the lacrimal gland that was treated with stereotactic radiosurgery (SRS) is presented. The aim of the present case report was to evaluate the effect of SRS in the treatment of a patient with ACC. Preliminary results confirmed that this method was highly effective in this patient. The patient is currently living with a good quality of life, normal vision and with no evidence of disease or complications. SRS exhibited reliable local tumor control and insignificant radiation-related complications, rendering it an encouraging treatment option for patients with recurrent or metastatic ACC.

Background: Radiation-induced cardiac events and pneumonitis are the major late radiotherapy side effects. Methods: We explored the differences in dose distribution between 3D CRT, IMRT and VMAT in 125 women with unilateral breast cancer. The various dose distribution to the tumor and OARs were studied for left and right sided irradiation. Results: Upon using 3D CRT breasts with lymph nodes, we observed a significant dose increase in the ipsilateral lung. Having irradiated only the right breast, there was a negligible Dmean difference to the adjacent lung between three methods, likewise for the myocardium in left breast cases. For right-sided cases 3D CRT showed the lowest doses in myocardium. Conclusion: Radiation oncologists should consider VMAT if conditions do not allow devising three plans with different methods. This in turn will reduce cardio and pneumotoxicity of left breast cancer treatment. In the treatment of right breast cancer, physicians should focus on 3D CRT.

154 Background: Local ablative therapy, such as radiation therapy or surgery plays a key role in treatment of patients with oligometastatic disease. Stereotactic ablative radiotherapy (SABR) comes to the fore as a safe and effective treatment option for patients with a limited number of metastases, even those located in hard-to-reach body sites. Many researchers have suggested that metastatic direct therapy (MDT) could improve long-term progression-free and overall survival (PFS and OS) in patients with 1-5 metastatic lesions. Methods: This was a retrospective, single-arm, observational, evaluation study between July 2015 to February 2022. In our institute 60 patients with controlled primary tumors and 1-5 metastases were treated with SABR.We did not exclude patients who subsequently had intracranial metastases from the analysis (n 3). Prescribed radiation doses ranged from 24 to 60 Gy administered in one to seven fractions. Primary endpoint was PFS and the secondary endpoints were OS and toxicity. Results: The most common primary malignancy types were prostate cancer (n 14), colon (n 10), lung (n 7), breast (n 6), melanoma (n 6) and gynecology malignancies (n 6). Median follow-up was 30 months, ranging from 9 to 79. The 1, 3 and 5-year OS rate was 98,3%, 84,4% and 73,8% respectively, the median time to first progression was 15 (range 2 - 32) months. 36 (60%) patients have no recurrence. Two of three patients with intracranial metastases were alive at the end of the study. There were no grade 3-5 adverse events related to specific treatment of SABR. In our analysis, neither the number of metastases nor the primary site were independent prognostic factors. Conclusions: In our retrospective analysis, SABR was associated with high levels of PFS and OS in patients with oligometastatic disease. The limitations of our study were lacking high-level evidence, randomized studies to compare SABR and palliative standard-of-care are mandatory.