Intensity-modulated radiotherapy outcomes for oropharyngeal squamous cell carcinoma patients stratified by p16 status.
BACKGROUND
Patients with oropharyngeal squamous cell carcinoma (OPSCC) treated with intensity-modulated radiotherapy (IMRT) were stratified by p16 status, neck dissection, and chemotherapy to correlate these factors with outcomes.


METHODS
A total of 112 patients with OPSCC treated with IMRT from 2002 to 2008 were retrospectively analyzed. All patients received RT to 66-70 Gray. Forty-five of the tumors were p16 positive (p16+), 27 were p16 negative (p16-), and 41 had unknown p16 status. Sixty-two patients had postradiation neck dissections. Nine patients with p16- tumors and 28 patients with p16+ tumors received chemotherapy. The distribution of T, N, and stage grouping among the p16+ and p16- patients was not significantly different, and 87.5% patients had stage III/IV disease.


RESULTS
The median follow-up was 26.3 months. For patients with p16+ tumors, p16- tumors, and the overall cohort, the actuarial 3-year locoregional progression-free survival rate was 97.8%,73.5%, and 90.5% respectively (P = .006) and the disease-free survival rate was 88.2%, 61.4%, and 81.7%, respectively (P = .004). Patients with p16+ tumors had an 89.5% and 87.5% pathologic complete response (CR) on neck dissection with and without chemotherapy, respectively. In contrast, patients with p16- tumors had a 66.7% and 25.0% pathologic CR on neck dissection with and without chemotherapy, respectively.


CONCLUSIONS
In this series, p16 status was found to be a significant predictive biomarker and patients with p16+ tumors had much better outcomes than patients with p16- tumors. Further investigation is warranted to determine whether less intense therapy is appropriate for selected patients with p16+ OPSCC, whereas more aggressive strategies are needed to improve outcomes in patients with p16- disease.
Department of Radiation Oncology, University of Virginia, Charlottesville, Virginia, USA.
Asal
A
Shoushtari
Mathew
M
Meeneghan
Ke
K
Sheng
Christopher A
CA
Moskaluk
Christopher Y
CY
Thomas
James F
JF
Reibel
Paul A
PA
Levine
Mark J
MJ
Jameson
Kimberly
K
Keene
Paul W
PW
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D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000532:radiotherapy*; D003131:Combined Modality Therapy; D019941:Cyclin-Dependent Kinase Inhibitor p16; D005260:Female; D019942:Genes, p16; D006801:Humans; D008297:Male; D008875:Middle Aged; D037981:Neck Dissection; D009363:Neoplasm Proteins / Q000378:metabolism; D009959:Oropharyngeal Neoplasms / Q000235:genetics* / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated; D016896:Treatment Outcome
C000614131:CDKN2A protein, human; D019941:Cyclin-Dependent Kinase Inhibitor p16; D009363:Neoplasm Proteins