After a discussion about the possibility of participating in the study, the patient is presented with an informed consent form and all questions of interest are explained. If consent to participate in the study is obtained, the patient and the researcher fill in all the required fields of two copies of the informed consent form and sign it. If necessary, the researcher re-explains any information regarding the study. One copy of the informed consent remains with the patient and the second copy is kept, as required by Good Clinical Practice, by the researcher.
Once informed consent has been obtained, an Individual Registration Card (IRC) is completed for the patient included in the study. Completion of the IRC also continues until all phases of the study are completed.
Pulmonary function tests, cardiopulmonary stress testing (CPST), indirect calorimetry are performed in patients with breast cancer who have undergone surgical treatment of the disease and referred for radiation therapy in the FGBU "NMC named after E.N. Meshalkin" of the Ministry of Health of Russia using MasterScreen Pneumo (Jaeger, Germany), Oxycon Pro ergospirometry (Jaeger, Germany), and indirect calorimetry systems for evaluation of external respiratory function in accordance with international standards. External respiration indices were adjusted to BTPS conditions (body temperature (37°C), ambient pressure and gas saturated with water vapor), and gas exchange - STPD (standard temperature (0°C or 273 K) and pressure (760 mm Hg) and no water vapor). The protocol of stress testing is selected individually, based on the proper values in accordance with the age, sex and anthropometric data of the patient. The study is conducted up to the individual maximum followed by a recovery period. The anaerobic threshold is determined using the V-slope method. After reaching the peak load, it is gradually reduced. Observation continues until full recovery of hemodynamic parameters, gas exchange, in case of adverse symptoms - until their disappearance. Repeated testing is performed in the first week after the end of the course of radiation therapy.
MSCT of the chest is performed on the 1-2 day of patient inclusion in the study to assess the initial state of the bronchopulmonary system of patients.
The SF-36 quality of life questionnaire, ECOG scale for assessing the general condition of the oncologic patient, mMRC respiratory disturbance scale, anxiety and depression scales, postcovicular functional limitations scale, and cognitive impairment scale are completed at inclusion in the study and after the course of radiation therapy.
Statistical analysis:
If the data are normally distributed, they will be compared using t-test, multivariate analysis of variance and χ2 test. If the data are not normally distributed, non-parametric tests will be used. A 95% confidence interval will be applied when calculating the mean and standard deviation/median and percentiles. Dependencies between continuous quantitative variables will be studied using linear regression, in case of discrete variables Spearman correlation will be used. Binary logistic regression will be applied to study qualitative traits having 2 categories. Manual stepwise variable inclusion technique will be used to formulate multivariate regression models with a cut-off point of significance level of 0.20. In all other cases, statistical significance will be established at a probability of type one error of less than 5%. All statistical analyses will be blinded.
