TGF-{beta}1 genetic variants predict clinical outcomes of HPV-positive oropharyngeal cancer patients after definitive radiotherapy

Purpose. Transforming growth factor-β1 (TGF-β1) plays a critical role in inflammation and immune responses and treatment response and survival. TGF-β1 variants may affect its expression level or functional efficiency, thus modifying tumor status and survival in HPV-positive squamous cell carcinoma of the oropharynx (SCCOP). Experimental design. We determined tumor HPV16 status and genotyped three TGF-β1 polymorphisms in 564 incident SCCOP patients treated with radiotherapy or chemoradiation. Univariate and multivariable Cox models were used to evaluate the associations between the three polymorphisms and survival. Results. Overall, 85% of patients (482 of 564) had HPV16-positive SCCOP. We found that TGF-β1 rs1982073 had statistically significant associations with survival, while TGF-β1rs1800469 and TGF-β1rs1800471 did not. Patients with TGF-β1 rs1982073 CT/CC variant genotypes had significantly better overall, disease-specific, and disease-free survival compared with those with the corresponding common homozygous TT genotype (all log-rank: P <0.001). Furthermore, these genotypes were significantly associated with an approximately 5 times reduced risk of overall death, death owing to disease, and recurrence after multivariable adjustment. Moreover, the stratified analyses by tumor HPV status indicated that the significant effects of TGF-β1 rs1982073 polymorphism on survival were found among HPV16-positive SCCOP patients only. Finally, the functional relevance of these variants was further characterized. Conclusions. Our findings support that the TGF-β1 rs1982073 polymorphism plays a significant role in the prognosis of SCCOP, especially in HPV16-positive SCCOP patients treated with chemoradiation. Prospective studies with larger sample sizes are needed to confirm these findings.

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