Preoperative intensity-modulated and image-guided radiotherapy with a simultaneous integrated boost in locally advanced rectal cancer: report on late toxicity and outcome.
OBJECTIVE
The addition of chemotherapy to preoperative radiotherapy has been established as the standard of care for patients with cT3-4 rectal cancer. As an alternative strategy, we explored intensity-modulated and image-guided radiotherapy (IMRT-IGRT) with a simultaneous integrated boost (SIB) in a prospective phase II study. Here, we report outcome and late toxicity after a median follow-up of 54 months.


METHODS
A total of 108 patients were treated preoperatively with IMRT-IGRT, delivering a dose of 46 Gy in fractions of 2 Gy. Patients (n=57) displaying an anticipated circumferential resection margin (CRM) of less than 2mm based on magnetic resonance imaging received a SIB to the tumor up to a total dose of 55.2 Gy.


RESULTS
The absolute incidence of grade ≥3 late gastrointestinal and urinary toxicity was 9% and 4%, respectively, with a 13% rate of any grade ≥3 late toxicity. The actuarial 5-year local control (LC), progression-free survival (PFS) and overall survival (OS) were 97%, 57%, and 68%. On multivariate analysis, R1 resection and pN2 disease were associated with significantly impaired OS.


CONCLUSIONS
The use of preoperative IMRT-IGRT with a SIB resulted in a high 5-year LC rate and non-negligible late toxicity.
Department of Radiotherapy, UZ Brussel, Vrije Universiteit Brussel, Belgium. Electronic address: benedikt.engels@gmail.com.
Benedikt
B
Engels
Department of Radiotherapy, UZ Brussel, Vrije Universiteit Brussel, Belgium.
Nele
N
Platteaux
Department of Radiotherapy, UZ Brussel, Vrije Universiteit Brussel, Belgium.
Robbe
R
Van den Begin
Department of Radiotherapy, UZ Brussel, Vrije Universiteit Brussel, Belgium.
Thierry
T
Gevaert
Department of Gastroenterology, UZ Brussel, Vrije Universiteit Brussel, Belgium.
Alexandra
A
Sermeus
Department of Radiotherapy, UZ Brussel, Vrije Universiteit Brussel, Belgium.
Guy
G
Storme
Department of Radiotherapy, UZ Brussel, Vrije Universiteit Brussel, Belgium.
Dirk
D
Verellen
Department of Radiotherapy, UZ Brussel, Vrije Universiteit Brussel, Belgium.
Mark
M
De Ridder
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011446:Prospective Studies; D061089:Radiotherapy, Image-Guided / Q000009:adverse effects / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods; D012004:Rectal Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D016896:Treatment Outcome
Helical tomotherapy; Image-guided radiotherapy; Intensity-modulated radiotherapy; Preoperative radiotherapy; Rectal cancer; Simultaneous integrated boost