Intensity-modulated radiotherapy for oral cavity squamous cell carcinoma: patterns of failure and predictors of local control.
OBJECTIVE
Few studies have evaluated the use of intensity-modulated radiotherapy (IMRT) for squamous cell carcinoma (SCC) of the oral cavity (OC). We report clinical outcomes and failure patterns for these patients.


METHODS
Between October 2002 and June 2009, 37 patients with newly diagnosed SCC of the OC underwent postoperative (30) or definitive (7) IMRT. Twenty-five patients (66%) received systemic therapy. The median follow-up was 38 months (range, 10-87 months). The median interval from surgery to RT was 5.9 weeks (range, 2.1-10.7 weeks).


RESULTS
Thirteen patients experienced local-regional failure at a median of 8.1 months (range, 2.4-31.9 months), and 2 additional patients experienced local recurrence between surgery and RT. Seven local failures occurred in-field (one with simultaneous nodal and distant disease) and two at the margin. Four regional failures occurred, two in-field and two out-of-field, one with synchronous metastases. Six patients experienced distant failure. The 3-year actuarial estimates of local control, local-regional control, freedom from distant metastasis, and overall survival were 67%, 53%, 81%, and 60% among postoperative patients, respectively, and 60%, 60%, 71%, and 57% among definitive patients. Four patients developed Grade ≥ 2 chronic toxicity. Increased surgery to RT interval predicted for decreased LRC (p = 0.04).


CONCLUSIONS
Local-regional control for SCC of the OC treated with IMRT with or without surgery remains unsatisfactory. Definitive and postoperative IMRT have favorable toxicity profiles. A surgery-to-RT interval of < 6 weeks improves local-regional control. The predominant failure pattern was local, suggesting that both improvements in target delineation and radiosensitization and/or dose escalation are needed.
Daly
Megan E
ME
Department of Radiation Oncology, Stanford University Medical Center, Stanford, CA 94305, USA.
Le
Quynh-Thu
QT
Kozak
Margaret M
MM
Maxim
Peter G
PG
Murphy
James D
JD
Hsu
Annie
A
Loo
Billy W
BW
Kaplan
Michael J
MJ
Fischbein
Nancy J
NJ
Chang
Daniel T
DT
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000401:mortality / Q000532:radiotherapy* / Q000556:secondary / Q000601:surgery; D003131:Combined Modality Therapy / Q000379:methods; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D007103:Immobilization / Q000379:methods; D008297:Male; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000188:drug therapy / Q000401:mortality / Q000532:radiotherapy* / Q000601:surgery; D009364:Neoplasm Recurrence, Local / Q000401:mortality; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods*; D013997:Time Factors; D017211:Treatment Failure; D055815:Young Adult