Effect of Irradiation Doses < 10 Gy and of Irradiated Bone Volume on the Variation of Blood Elements of the Complete Blood Count During and After Pelvic Irradiation

Overview

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 pelvic lymph node areas, especially when concomitant chemotherapy is used, volume of bone marrow irradiated is large and dose to the bone marrow is high. There is a lack of prospective studies and comparative trials to customize the constraints according to the presence or absence of chemotherapy and correlated to the patient's bone marrow potential. This multicentric and prospective study conducted by Strasbourg Europe Cancerology Institute aims to evaluate hematological toxicity (anemia, thrombocytopenia, leukopenia) in patients treated with pelvic irradiation for prostate, rectum, anal canal, endometrium, cervix cancer or vaginal cancer. One hundred patients will be included in the study, including patients treated with exclusive radiotherapy, radiochemotherapy, or radiohormonal therapy. 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. Hematological toxicity will be measured by weekly blood count during radiotherapy and at one month and three months after the end of radiotherapy. Secondary endpoints are the evaluation of viral, bacterial and fungal infections during and for three months following radiotherapy, as well as the evaluation of the impact of radiation-induced hematological toxicity on the administration of chemotherapy for the concerned patients. 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.

Patients will be identified as potentially eligible for inclusion once radiotherapy has been decided upon at the multidisciplinary consultation meeting. During the radiotherapy consultation, the study will be offered to the patient if they also meet the other inclusion criteria. As soon as the consent is signed and before the first radiotherapy session, a first biological check-up including a blood count and renal function will be performed. This biological investigation will serve as a reference. During the dosimetric computer-tomography scan for radiotherapy, bony structures will be delineated, iliac bones, lower pelvis, femoral heads, lumbosacral spine and entire pelvis. Dosimetry will be performed in the same way whether patients are included in the study or not, they will receive between 25Gy in 5 fractions and 78Gy in 39 fractions, depending on the primary tumor. The dose volume histograms will be received. During treatment, patients will have a weekly blood test starting from the second week of treatment. At one months and three months after the end of the radiotherapy, patients will be seen in consultation and will also have a blood test.