Locally advanced primary colorectal cancer: intraoperative electron and external beam irradiation +/- 5-FU.
OBJECTIVE
For locally advanced primary colorectal cancer, our institution has combined intraoperative electron irradiation (IOERT) with external beam irradiation (EBRT) +/- 5-fluorouracil (5-FU) and surgical resection. Disease control and survival were compared with the current IOERT and prior non-IOERT regimens.


METHODS
From April 1981 through August 1995, 61 patients received an IOERT dose of 10-20 Gy, usually combined with 45-55 Gy of fractionated EBRT; 56 had minimum follow-up of 18 months. The amount of residual disease remaining at IOERT after exploration and maximal resection in the 56 patients was gross in 16, < or = microscopic in 39, and unresected in 1.


RESULTS
Survival (SR) and disease control were analyzed as a function of potential prognostic factors. Factors that achieved statistical significance for improved overall survival included treatment sequence of preop EBRT + 5-FU (vs. postoperative EBRT + 5-FU, p = 0.003) and < or = microscopic residual disease after maximal resection (vs. gross residual, p = 0.005). Those that appeared to favorably impact disease-free survival included EBRT + 5-FU (vs. EBRT alone, p = 0.01), < or = microscopic residual (vs. gross, p = 0.0014), and colon site of primary (vs. rectum, p = 0.009). Failures within an irradiation field have occurred in 4 of 16 patients (25%) who presented with gross residual after partial resection vs. 2 of 39 (5%) with < or = microscopic residual after gross total resection (p = 0.01). The significant prognostic factors for a decrease in distant metastases were the same as for disease-free SR with respective p-values of 0.013 (EBRT + 5-FU), 0.008 (microscopic residual), and 0.03 (colon primary). The current data suggests a relationship between IOERT dose and incidence of Grade 2 or 3 neuropathy (< or = 12.5 Gy--1 of 29 or 3%, > or = 15 Gy--6 of 26 or 23%, p = 0.03).


CONCLUSIONS
Both overall survival and disease control appear to be improved with the addition of IOERT to standard treatment. More routine use of systemic therapy is indicated as a component of IOERT containing treatment regimens because the incidence of distant metastases was 50% of patients at risk.
Gunderson
L L
LL
Department of Radiation Oncology, Mayo Clinic and Mayo Medical School, Rochester, MN 55905, USA.
Nelson
H
H
Martenson
J A
JA
Cha
S
S
Haddock
M
M
Devine
R
R
Fieck
J M
JM
Wolff
B
B
Dozois
R
R
O'Connell
M J
MJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000964:Antimetabolites, Antineoplastic / Q000627:therapeutic use; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D003131:Combined Modality Therapy; D004583:Electrons / Q000627:therapeutic use*; D005260:Female; D005472:Fluorouracil / Q000627:therapeutic use; D006801:Humans; D007432:Intraoperative Period; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D018365:Neoplasm, Residual; D010523:Peripheral Nervous System Diseases / Q000209:etiology / Q000473:pathology; D011446:Prospective Studies; D012004:Rectal Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D016019:Survival Analysis; D017211:Treatment Failure
D000964:Antimetabolites, Antineoplastic; D005472:Fluorouracil