Retrospective evaluation of the contribution of radiotherapy to survival in breast cancer treatment with propensity score based on stage and subgroup.

BACKGROUND: Breast cancer has been a disease in which treatment strategy has changed over time under the influence of different hypotheses and evidence for more than a century. We analyzed the contribution of radiotherapy to disease-free survival and overall survival by classifying according to stage, 1-3 lymph node involvement, and molecular subgroups. METHODS: Following the approval of the Institutional Review Board, records of patients with breast cancer who were admitted to University School of Medicine Departments of Radiation Oncology and Medical Oncology between July 1999 and December 2020 were reviewed. Using data propensity score matching was performed between the groups that did and did not receive radiotherapy using an optimal matching algorithm (optimum, 1:1). Disease-free survival and overall survival after propensity score matching were calculated using the Kaplan-Meier method. Univariate and multivariate Cox regression analysis was used to estimate hazard ratios. RESULTS: In the radiotherapy and non-radiotherapy groups, disease-free survival was 257.42 ± 5.46 (246.72- 268.13), 208,96 ± 8,15 (192,97-224,94) months respectively, (p = < 0.001), overall survival was 272,46 ± 8,68 (255,43-289,49), 219,05 ± 7,32 (204,70-233,41) months respectively (p = .002). We compared the 19 N1 patient groups who received radiotherapy with the 19 patients who did not receive radiotherapy and calculated the disease-free survival times was 202,21 ± 10,50 (181,62-222,79) and 148,82 ± 24,91 (99,99-197,65) months respectively (p = .011) and overall survival times was 200,85 ± 12,79 (175,77-225,92) and 166,90 ± 20,39 (126,93-206,82) months respectively (p = .055). We examined disease-free survival and overall survival times in both groups according to Luminal A, Luminal B, TNBC, and HER2-enriched subgroups. In the Luminal B subgroup, the disease-free survival duration in the groups receiving radiotherapy and not receiving radiotherapy was 264.83 ± 4.95 (255.13-274.54) and 187.09 ± 11.06 (165.41-208.78) months (p < .001), and overall survival times were 252.29 ± 10.54 (231.62-272.97) and 197.74 ± 9.72 (178.69-216.80) months (p = .001) respectively. CONCLUSIONS: Thanks to studies proving that RT increases long-term survival rates in breast cancer as a result of reducing locoregional recurrence and systemic metastasis rates, it has been understood that the spectrum hypothesis is the hypothesis that most accurately describes breast cancer to date. We found that patients with Luminal B invasive breast cancer benefited significantly more from RT compared to other subgroups.

The Impact of Everolimus and Radiation Therapy on Pulmonary Fibrosis.

Background and objectives: Everolimus (EVE) is a mammalian target of the rapamycin (mTOR) inhibitor that is widely used in cancer patients. Pulmonary toxicity, usually manifesting as interstitial pneumonitis, is a serious adverse effect of this drug. Radiation therapy, which is often administered in conjunction with chemotherapy for synergistic effects, also causes pulmonary fibrosis. In view of pulmonary damage development in these two forms of cancer treatment, we have examined the effect of EVE administration individually, in combination with radiation given in varying sequences, and its relation to the extent of pulmonary damage. Materials and Methods: We performed an experimental study in albino rats, which were randomized into five groups: (1) control group, (2) EVE alone, (3) EVE 22 h after radiation, (4) EVE 2 h after irradiation, and (5) only radiation. Sixteen weeks after thoracic irradiation, rat lung tissue samples were examined under light microscopy, and the extent of pulmonary damage was estimated. After this, we calculated median fibrosis scores in each group. Results: The highest fibrosis score was noted in Group 4. Among the five groups, the control group had a significantly lower median fibrosis score compared to the others. When the median fibrosis score of the group that received concurrent EVE with radiation therapy (RT) (Group 4) was compared with that of the control group, the difference was statistically significant (p = 0.0022). However, no significant differences were achieved among the study groups that received EVE only or RT only, whether concurrently or sequentially (p > 0.05). Conclusion: EVE is an effective treatment option for the management of several malignancies and is often combined with other therapies, such as radiation, for a more efficient response. However, an increased risk of pulmonary fibrosis should also be anticipated when these two modalities are combined, as they both can cause pulmonary damage, especially when administered concurrently.

Evaluation of the physical and biological dosimetry methods in iodine-131-treated patients.

The aim of the study was to compare physical and biological dosimetry methods in iodine-131 (I-131)-receiving patients. The present study comprised of 47 patients (mean age: 47.9 ± 15.8 years), treated with I-131. Group I consisted of 17 patients with hyperthyroidism and mean administered activity of this group was 432.9 ± 111 MBq. There were 15 follow-up patients of differentiated thyroid cancer (DTC) in Group II with mean administered activity of 185 ± 22.2 MBq, who were administered scanning dose of I-131. Group III comprised of 15 patients with DTC, ablated with high-dose of I-131, and this group's mean administered activity was 4347.5 ± 695.6 MBq. The whole-body absorbed doses were calculated in all patients both with the Medical Internal Radiation Dosimetry (MIRD) method using MIRDOSE3 software and cytokinesis-block micronucleus (MN) assay-based MN analysis and were compared. The whole-body absorbed dose, calculated by MIRD method, showed very good correlation with the administered I-131 activity (r = 0.89, P < 0.001), but it was moderate in the MN method (r = 0.52, P < 0.01). Absorbed dose estimations with MIRD method were 49.2 ± 20.8 mGy in Group I, 6.5 ± 1.6 mGy in Group II, and 154.3 ± 47.8 mGy in Group III; the differences were statistically significant (P < 0.001), as expected. Pre- and posttreatment MN frequencies differed significantly in all groups (P < 0.05). The whole-body absorbed doses, based on MN method, were 68.2 ± 17.5, 46.0 ± 11.4, and 90.5 ± 26.9 mGy in Groups I-III, respectively. The difference was significant between Group II and Group III (P < 0.01). The mean absorbed dose was 74.6 ± 27.9 mGy with MN versus 68.0 ± 67.1 mGy in MIRD method (P = 0.087) in the entire study population and the correlation was moderate (r = 0.73, P < 0.001). The whole-body absorbed doses, estimated by MN method, showed moderate correlation with administered radioiodine activities in low radioiodine doses and had significantly different and fluctuating values as compared to MIRD method in patients treated with I-131.

An institutional experience of quality assurance of a treatment planning system on photon beam.

AIM: The purpose of the present study is to show the application of the IAEA TRS-430 QA procedures of Eclipse™v7.5 TPS for photon energies. In addition, the trends of the deviations found in the conducted tests were determined. BACKGROUND: In the past, the lack of complete TPS QA procedures led to some serious accidents. So, QA in the radiotherapy treatment planning process is essential for determination of accuracy in the radiotherapy process and avoidance of treatment errors. MATERIALS AND METHODS: The calculations of TPS and measurements of irradiations of the treatment device were compared in the study. As a result, the local dose deviation values (δ 1: central beam axis, δ 2: penumbra and build up region, δ 3: inside field, δ 4: outside beam edges, δ 50-90: beam fringe, RW50: radiological width) and their confidence limit values (including systematic and random errors) were obtained. RESULTS: The confidence limit values of δ 4 were detected to increase with expanding field size. The values of δ 1 and δ 3 of hard wedge were larger than open fields. The values of δ 2 and δ 50-90 of the inhomogeneity effect test were larger, especially than other tests of this study. The average deviation was showed to increase with the rise of the wedge angle. The values of δ 3 and δ 4 of lung irradiation were outside tolerance. CONCLUSIONS: The QA of TPS was done and it was found that there were no reservations in its use in patient treatment. The trend of the deviations is shown.

The effects of therapeutic x-ray doses on mechanical, chemical and physical properties of poly methyl methacrylate.

AIM: The aim of this study was to investigate the effect of radiation doses very close to the human dose for oral cancers on mechanical, chemical and physical properties for poly methyl-methacrylate (PMMA). METHODS: PMMA samples were divided into four different groups: no irradiated group, 25-Gy irradiated group, 50-Gy irradiated group and 75-Gy irradiated group. Each group contained nine samples. After 24 h, a three-point loading test was applied to each PMMA groups. The transverse strength and the elastic modulus were calculated using the test results. The results were analyzed statistically by using one-way analysis of variance. The structural characterizations of the PMMA samples were carried out by a Fourier Transform Infrared (FTIR) spectrophotometer to evaluate the chemical structure differences. RESULTS: The transverse strength values of 25-Gy, 50-Gy and 75-Gy radiation groups were significantly higher than that of the no radiation group (p < 0.05). There was no significant difference among the elastic modulus values of the study groups (p > 0.05). The FTIR findings demonstrated that the irradiation process did not change the chemical structure of the PMMA polymeric materials. CONCLUSION: The therapeutic radiation doses increase the mechanical properties of the PMMA; however, the chemical and structural properties have no effect. When the findings of this study are taken into account, it can be said that patients can wear dentures during the radiotherapy.

Concentration modulated skin marker for radiotherapy treatment planning process.

BACKGROUND AND PURPOSE: For conformal radiotherapy, it is feasible to achieve high accuracy in contouring the outline of the target volume in treatment planning process. In contouring process, target volume is occasionally defined by means of either surgical clips or skin marker during patient anatomical data acquisition. Treatment planning systems are predicting invalid radiation dose distributions by using surgical clips and skin marker within the patient. Purpose of this study is the production of new skin marker which affects less dose distributions of electron beam. MATERIALS AND METHODS: The influences of lead and commercial markers on dose calculations in a 3D treatment planning systems were investigated in terms of electron beam energy and dose profile depth. Dose deviation with commercial marker was observed to smaller than lead marker. However this dose deviation was still at big value. In order to reduce of this value, barium sulfate suspension and ultrasound gel were mixed with different volumetric ratio. With the purpose of acception the most suitable marker for radiation therapy, obtained new suspensions were investigated in terms of visibility and dose deviation. RESULTS: B:G/1:10 marker was determined to cause optimum visibility and the lowest dose deviation on dose calculations in terms of electron beam energy and dose profile depth. CONCLUSIONS: Appropriate marker, mixture of substances such as barium sulfate suspension and ultrasound gel can be produced. This marker is both ease of usage and practical and economical. Each clinic can prepare marker which is peculiar to suspension with different concentration of substance for specific visibility. But, it should be taken into account resultant dose deviation to beam calculation depending on barium sulfate concentration.