Patterns of failure and local control after intraoperative electron boost radiotherapy to the presacral space in combination with total mesorectal excision in patients with locally advanced rectal cancer.
OBJECTIVE
To evaluate local control and patterns of failure in patients treated with intraoperative electron beam radiotherapy (IOERT) after total mesorectal excision (TME), to appraise the effectiveness of intraoperative target definition.


METHODS
We analyzed the outcome of 243 patients with rectal cancer treated with IOERT (median dose, 10 Gy) after TME. Eighty-eight patients received neoadjuvant and 122 patients adjuvant external beam radiotherapy (EBRT) (median dose, 41.4 Gy), and in 88% simultaneous chemotherapy was applied. Median follow-up was 59 months.


RESULTS
Local failure was observed in 17 patients (7%), resulting in a 5-year local control rate of 92%. Only complete resection and absence of nodal involvement correlated positively with local control. Considering IOERT fields, seven infield recurrences were seen in the presacral space, resulting in a 5-year local control rate of 97%. The remaining local relapses were located as follows: retrovesical/retroprostatic (5), anastomotic site (2), promontorium (1), ileocecal (1), and perineal (1).


CONCLUSIONS
Intraoperative electron beam radiotherapy as part of a multimodal treatment approach including TME is a highly effective regimen to prevent local failure. The presacral space remains the site of highest risk for local failure, but IOERT can decrease the percentage of relapses in this area.
Roeder
Falk
F
Department of Radiation Oncology, University of Heidelberg, Heidelberg, Germany.
Treiber
Martina
M
Oertel
Susanne
S
Dinkel
Julien
J
Timke
Carmen
C
Funk
Angela
A
Garcia-Huttenlocher
Helena
H
Bischof
Marc
M
Weitz
Jürgen
J
Harms
Wolfgang
W
Hensley
Frank W
FW
Buchler
Markus W
MW
Debus
Jürgen
J
Krempien
Robert
R
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004583:Electrons / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007432:Intraoperative Period; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy / Q000379:methods; D009364:Neoplasm Recurrence, Local / Q000517:prevention & control*; D018714:Radiotherapy, Adjuvant / Q000379:methods; D012004:Rectal Neoplasms / Q000532:radiotherapy* / Q000601:surgery*; D017211:Treatment Failure