Pretreatment Primary Tumor SUVmax Measured by FDG-PET and Pathologic Tumor Depth Predict for Poor Outcomes in Patients With Oral Cavity Squamous Cell Carcinoma and Pathologically Positive Lymph Nodes

Purpose

The pathologic tumor depth is an independent prognosticator for local control (LC) and survival in patients with oral cavity squamous cell carcinoma (OSCC). We sought to investigate the prognostic value of the preoperative maximal standardized uptake value (SUVmax) at the primary tumor in OSCC patients with pathologically positive lymph nodes.

Methods and Materials

A total of 109 OSCC patients with pathologically positive lymph nodes were investigated. All patients underwent 2-deoxy-2[(18)F]fluoro-d-glucose–positron emission tomography within 2 weeks before surgery and neck dissection. All patients were followed for ≥24 months after surgery or until death. The optimal cutoff value for the primary tumor SUVmax was selected according to the 5-year LC rate. Independent prognosticators were identified by Cox regression analysis.

Results

The median follow-up for all patients was 26 months (39 months for surviving patients). A cutoff SUVmax of 19.3 provided the greatest prognostic information for the 5-year LC rate (55% vs. 88%, p = 0.0135). A tumor depth ≥12 mm appeared to be the most appropriate cutoff for predicting the 5-year LC rate (76% vs. 95%, p = 0.0075). A scoring system using the primary tumor SUVmax and tumor depth was formulated to define distinct prognostic groups. Patients with both a SUVmax of ≥19.3 and tumor depth of ≥12 mm (n = 8) had significantly poorer 5-year LC, 5-year disease-free, 5-year disease-specific, and 5-year overall survival rates compared with the other patient groups.

Conclusion

The combination of the primary tumor SUVmax (≥19.3) and pathologic tumor depth (≥12 mm) identified a subgroup of OSCC patients at greatest risk of poor LC and death.

Introduction

Taiwan is an endemic betel quid chewing area, and oral cavity cancer remains a leading cause of morbidity and mortality in our country. According to the 2008 Department of Health statistics, oral cavity cancer is the sixth leading cancer in the Taiwanese general population. In men, oral cavity cancer is fourth leading form of cancer and the fourth leading cause of death (1). In this context, we sought to gain a better insight of the potential prognostic factors in this clinical entity that might hold promise to improve patient outcomes. It is well-known that the characteristics of the deep invasive front area of oral cavity squamous cell carcinoma (OSCC) can reflect the tumor prognosis better than other parts of the tumor 2, 3, 4. Tumor depth represents a variable that defines tumor quantity but that at the same time introduces a qualitative aspect with regard to the aggressiveness of local infiltration. In this regard, tumor depth is a strong predictor of the probabilities of regional lymph node metastases, the likelihood of involvement of distant node groups, and the risk of distant metastases 5, 6, 7, 8, 9, 10, 11.

We have previously shown that tumor depth is of greater prognostic value than tumor stage (pT1-pT2 vs. pT3-pT4) in predicting locoregional control and survival among OSCC patients 5, 6, 7. Moreover, the presence of pathologically positive lymph nodes indicates a poor prognosis in this patient group 5, 6, 7, 8, 9, 10, 11, 12. The identification of objective pathologic prognostic determinants in OSCC might enable better patient selection for adjuvant therapy. Some OSCC patients with pathologically positive lymph nodes have a poor outcome even after radical surgery or composite resection with neck dissection (ND). In this context, the identification of OSCC patients at high risk of relapse after radical surgery would have major clinical implications for patient treatment.

Positron emission tomography (PET) using 2-deoxy-2[(18)F]fluoro-d-glucose (FDG) has been widely used in the treatment planning process of head-and-neck cancer patients 13, 14, 15, 16, 17, 18. It is unclear, however, whether high pretreatment uptake of FDG detected by PET measured at the primary tumor predicts poor outcomes for OSCC patients undergoing radical surgery and ND.

The aim of this prospective study was to investigate the prognostic value of the preoperative maximal standardized uptake value (SUVmax) at the primary tumor and other clinicopathologic characteristics in relation to local control (LC) and survival in OSCC patients with pathologically positive lymph nodes.