Prognostic indicators of survival for patients with oral cavity squamous cell carcinoma in Norway. Outcomes in a retrospective, multicenter cohort, with special focus on oral tongue squamous cell carcinoma, 2005-2009

Abstract

Oral cavity cancer (OCC) is the most frequent of head and neck cancers, most being squamous cell carcinomas (SCC). Within the oral cavity, the oral tongue is the most common site of cancer. These cancers are very aggressive, with poor survival. The treatment decision is based upon classifications of tumor (T), lymph node (N), and metastasis (M), although tumors with the same classification may act differently in aggressiveness. Treatment of these patients would be primary site surgery, with additional neck-dissection for many. Postsurgical radiotherapy may be added, rarely chemotherapy. The tumor growth pattern may predict the aggressiveness of the tumor, and thereby supplement the TNM classification in treatment decision. There is no established tumor growth pattern in use today that differentiates between those who need an additional neck-dissection and radiotherapy or chemotherapy; this may lead to overtreatment or undertreatment. This study investigated retrospectively a cohort of OCC from 2005-2009, which was called the Norwegian oral cancer (NOROC) study. We used data from the national Cause of Death Registry to calculate survival outcome. Spearman bivariate calculation was used to investigate correlations between the variables. Log-Rank univariate analyses were used to give Kaplan-Meier survival curves. Cox regression was used in multivariate analyses to determine which variables best predicted survival outcome. We found 535 primary treatment-naïve oral cavity SCC. Median age at diagnosis was 67 years; five-year disease-specific survival was 52%. Our data show that high-risk Human Papilloma Virus was not detected in oral tongue (OT) SCC. Growth patterns of tumor depth of invasion (DOI), tumor budding, and WHO differentiation and lympocytic infiltate in a combined histo-score, can predict the aggressiveness. Tumor DOI is already implemented in the new TNM classification. We suggest that other risk-patterns we found can be added to TNM classification for individualized treatment.