Adjuvant volumetric-modulated arc therapy with simultaneous integrated boost in endometrial cancer. Planning and toxicity comparison.
OBJECTIVE
To report dosimetric and acute toxicity data in prospectively enrolled high-intermediate risk endometrial cancer (HIR-EC) patients postoperatively irradiated by simultaneous integrated boost volumetric modulated arc therapy (SIB-VMAT).


METHODS
Thirty prospectively enrolled HIR-EC patients were postoperatively treated by SIB-VMAT. Target coverage, dose homogeneity, and sparing of organs at risk (OARs) were compared with corresponding data retrieved from an historical control (30 consecutive selected matched patients) treated by concomitant boost three-dimensional conformal radiotherapy (3D CRT CB) from a previously published study (ADA-I trial). All patients received 45 Gy on pelvic lymph nodes plus 10 Gy boost on the vaginal vault.


RESULTS
The SIB-VMAT technique produced more inhomogeneous plans than 3D CRT CB, but showed significantly better conformity index (CIs) for both PTVs. SIB-VMAT was associated with significant reduction in the irradiated small bowel (SB) volume compared with 3D CRT CB for all dose range > 10 Gy (e.g. V15: 163.5 cm(3) vs. 341.3 cm(3), p = 0.001 and V40: 43.8 cm(3) vs. 85.2 cm(3), p = 0.008). With regard to bladder and rectum, SIB-VMAT showed a significant sparing advantage at all dose levels with respect to 3D CRT CB retrieved plans. Moreover, overall OARs Dmean were significantly reduced by the SIB-VMAT (p = 0.001). According to CTCAE v.4.0, acute (within three months) GI toxicities were more frequent in 3D CRT CB versus SIB-VMAT (90.0% vs. 66.7%; p-value 0.028).


CONCLUSIONS
Compared to data from a historical database of patients administered 3D CRT CB, SIB-VMAT significantly improves the dose conformity and sparing of OARs in HIR-EC patients undergoing postoperative radiotherapy. The improvement in terms of acute toxicity justifies further prospective clinical evaluation.
Radiotherapy Unit, Department of Oncology, Fondazione di Ricerca e Cura "Giovanni Paolo II", Università Cattolica del S. Cuore , Campobasso , Italy.
Gabriella
G
Macchia
Savino
S
Cilla
Alessio Giuseppe
AG
Morganti
Francesco
F
Deodato
Francesco
F
Legge
Angelo
A
Piermattei
Vito
V
Chiantera
Giovanni
G
Scambia
Vincenzo
V
Valentini
Gabriella
G
Ferrandina
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016889:Endometrial Neoplasms / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D008875:Middle Aged; D058958:Organs at Risk; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects*