The incidence, severity, and onset of radiation-induced
emesis (RIE) are related to field size, site, and dose per fraction. Radiation-induced
emesis can occur (1) within 2 to 3 weeks in approximately 50% of patients after conventional fractionated
radiotherapy (200 cGy/fraction) to the upper abdomen, (2) acutely in more than 90% of patients receiving fractionated total body irradiation (TBI) for
bone marrow transplantation, and (3) within 30 to 60 minutes in more than 80% of patients following single high-dose (> 500 cGy)/large field
hemibody irradiation (HBI). The increased frequency of
emesis associated with TBI and HBI has renewed the interest in the mechanism and treatment of RIE. A number of studies have reported a significant difference in the incidence of
emesis following doses of > or = 500 cGy to the upper-mid (> 80%) and lower (20% to 40%) hemibody. The data suggested that the organ responsible for
emetic response was in the upper abdomen. However, the mechanism of RIE is not well understood, although degradation products from normal tissues and
tumor have been suggested. The introduction and effectiveness of the 5-hydroxytryptamine3 receptor antagonists in
chemotherapy-induced
emesis and the location of these receptors in the upper abdomen (possible site of the radiation-associated
emetic response) suggested that this group of compounds may have a role in RIE. Lucraft and Palmer (Clin Radiol 33:621-622, 1982) reported no differences between
levonantradol and
chlorpromazine in preventing RIE in patients treated with single doses of more than 10 Gy to a small upper abdominal field. Priestman (Eur J
Cancer Clin Oncol 25:529-533, 1989 [Suppl]) reported on a pilot and randomized study with
ondansetron after single doses of 8 to 10 Gy to the upper abdomen. In the pilot study,
ondansetron achieved major or complete control of
vomiting in 77% to 90% of patients; subsequently, he reported a significant difference between
ondansetron (97%) and
metoclopramide (45%) in controlling RIE on the day of
radiotherapy. Hewitt et al (Bone Marrow Transpl 7:431-433, 1991) reported a complete or major response on 93% of the days of
ondansetron therapy during pretreatment
therapy with
cyclophosphamide and TBI for
bone marrow transplantation. A preliminary analysis of 41 patients treated with HBI at the Rex
Cancer Center confirms the role of
ondansetron in RIE. Twenty-eight patients (upper-mid 16 patients/lower HBI 12 patients) did not receive pretreatment
antiemetics (group A); seven received non-
ondansetron pre-HBI (group B); and six received
ondansetron (group C).(ABSTRACT TRUNCATED AT 400 WORDS)