Effects of irradiation doses <10 Gy and irradiated bone volume on the change in blood counts during and after pelvic irradiation

Abstract

Background: Bone marrow is one of the organs at risk of complications during irradiation due to its radiosensitivity. Hematopoietic toxicity remains one of the main toxicities during irradiation of pelvis. Modern radiotherapy techniques, such as intensity modulation and three-dimensional conformal radiotherapy, allow for better dose compliance in target volumes while optimally sparing organs at risk. There is a lack of prospective studies and comparative trials specifying the dose constraints according to the presence or absence of chemotherapy and correlating with the patient’s bone marrow potential. Methods: This monocentric and prospective study conducted by the Strasbourg Europe Cancerology Institute aims to evaluate the hematological toxicity in patients treated with pelvic irradiation for prostate, rectum, anal canal, endometrium, or cervix cancer. One hundred patients will be included. The primary objective is to quantify the relationship between acute hematological toxicity and delivered doses and irradiated volumes in pelvic bone marrow for pelvic cancers. The prescribed dose to the pelvis depends on the tumor location, from 25 Gy in 5 fractions for rectal cancer to 78 Gy in 39 fractions for low-risk prostate cancer. Hematological toxicity will be measured by weekly blood count during radiotherapy and at one month and three months after the end of radiotherapy. Conclusions: The aim of this study is to improve and optimize radiotherapy if a dose limit or volume constraint is imposed by the results of the study. To our knowledge, this is the first study including several types of pelvic cancers and involving patients treated exclusively with radiotherapy, chemoradiotherapy or radiohormonotherapy. Trial Registration: Trial registration number is NCT04626466.