Intensification of radiation therapy for
 localized breast cancer in the settings of the
 COVID-19 pandemic: A literature review

Abstract

Relevance: Since 2004, breast cancer steadily ranks first in the
 structure of the incidence of malignant neoplasms in the Republic of
 Kazakhstan in both sexes. In 2020, its share was 14.5% (vs. 15.2% in
 2019). Breast cancer also constantly ranks first in the structure of female cancer incidence, with 44.3‰ in 2020 (vs. 51.6‰in 2019).
 In the early 1980s, radiation therapy was a standard specialized
 treatment for breast cancer. The current realities of the COVID-19
 pandemic require a reorganization of healthcare facilities to determine the priorities. It is also important to balance the economic and
 clinical efficacy of radiotherapy methods applied.
 The study aimed to analyze the results of large randomized trials and compare breast cancer outcomes after hypofractionated and standard fractionation radiation treatment.
 Methods: We reviewed the results of large randomized trials
 of hypofractionated radiation therapy, emphasizing adequate
 patient selection according to the American Society of Therapeutic Radiology and Oncology (ASTRO) guidelines. Radiobiological
 aspects of hypofractionation were considered due to its implementation in clinical practice. The research materials were obtained from the “PubMed” database of evidence-based medicine
 by the keywords “radiotherapy,” “breast cancer,” “hypofractionation dose” for the period 2000-2021. Large randomized trials
 involving patients of any age diagnosed with stages T1-3, N0-1
 breast cancer, who underwent beam therapy in standard or hypofractionated mode, met the criteria for inclusion in this study.
 Results: According to the results of large randomized trials,
 the hypofractionated regimen is similar to the standard regimen in terms of late effects on normal tissues and ensures good
 control over the oncological process.
 Conclusions: Hypofractionation has proven effectiveness
 and safety and has lower late and/or acute radiation toxicity
 when treating early breast cancer. Hypofractionation can become a new standard of radiation therapy at early stages after
 breast-conserving surgery.