Prognostic significance of tumor-infiltrating lymphocytes in oropharyngeal cancer.

The presence of tumor-infiltrating lymphocytes has been shown to significantly improve clinical outcomes in many types of cancer. However; their effects on outcomes in patients with oropharyngeal cancer specifically have yet to be elucidated. We conducted a retrospective study in an effort to shed light on this issue. We reviewed the records of 48 consecutively presenting patients with oropharyngeal cancer; and we performed immunohistochemistry to analyze their archived paraffin-embedded tissue samples for the presence of CD3-positive tumor-infiltrating lymphocytes. We also used real-time polymerase chain reaction testing to look for human papillomavirus type 16 (HPV-16) in the tumors. We found that patients with large numbers of tumor-infiltrating lymphocytes (CD3high) had a significantly lower incidence of metastasis at presentation than did those with low numbers of tumor-infiltrating lymphocytes (CD31low) (40.0 vs. 88.5%; p = 0.001), regardless of HPV status. When HPV status was taken into account, the correlation between a high CD3 count and a lower rate of metastasis was maintained in the HPV-positive patients but not in the HPV-negative patients. We also found that the CD3high patients had higher rates of overall survival and disease-free survival at 3 and 5 years than did the CD3low patients; however; these differences only approached but did not reach statistical significance.