The volume effect in radiation-related late small bowel complications: results of a clinical study of the EORTC Radiotherapy Cooperative Group in patients treated for rectal carcinoma.
OBJECTIVE
The purpose of this study was to quantify the correlation between irradiated small bowel volume and late occurring small bowel complications.


METHODS
Small bowel volumes in the high-dose region were measured using orthogonal barium films for 203 patients treated for rectal carcinoma with pelvic postoperative radiotherapy to 50 Gy in an EORTC multicentric study.


RESULTS
The 5-year estimate of late pelvic small bowel obstruction requiring surgery was 11%. No correlation between the irradiated small bowel volume and obstruction was detected. The actuarial 5-year estimate of chronic diarrhea varied from 31% in patients with irradiated small bowel volumes below 77 cm3 to 42% in patients with volumes over 328 cm3. This correlation was significant in the univariate and multivariate analysis (p = 0.025). The type of rectal surgery significantly influenced the incidence of chronic diarrhea and malabsorption, the actuarial 5-year estimate being 49% and 26% after low anterior resection and abdominoperineal resection, respectively (p = 0.04).


CONCLUSIONS
This study demonstrated that there is a volume-effect in radiation-induced diarrhea at a dose of 50 Gy in 25 fractions. No volume-effect for small bowel obstruction was detected at this dose-level in pelvic postoperative radiotherapy. A review of the literature data on small bowel obstruction indicates that the volume effect at this dose level can only be demonstrated in patients who were treated with extended field radiotherapy (estimated small bowel volume 800 cm3) after intra-abdominal surgery.
University of Amsterdam, Department of Radiotherapy, The Netherlands.
J G
JG
Letschert
J V
JV
Lebesque
B M
BM
Aleman
J F
JF
Bosset
J C
JC
Horiot
H
H
Bartelink
L
L
Cionini
J P
JP
Hamers
J W
JW
Leer
M
M
van Glabbeke
D000206:Actuarial Analysis; D001466:Barium Sulfate; D002277:Carcinoma / Q000532:radiotherapy*; D002908:Chronic Disease; D003967:Diarrhea / Q000209:etiology; D004307:Dose-Response Relationship, Radiation; D005500:Follow-Up Studies; D006801:Humans; D007415:Intestinal Obstruction / Q000209:etiology* / Q000601:surgery; D007421:Intestine, Small / Q000000981:diagnostic imaging / Q000528:radiation effects* / Q000601:surgery; D008286:Malabsorption Syndromes / Q000209:etiology; D015999:Multivariate Analysis; D011379:Prognosis; D011832:Radiation Injuries / Q000209:etiology* / Q000601:surgery; D011859:Radiography; D011879:Radiotherapy Dosage; D012004:Rectal Neoplasms / Q000532:radiotherapy*; D012189:Retrospective Studies; D015996:Survival Rate
D001466:Barium Sulfate