Value of Volumetric Staging and Hematologic Indices As an Alternative to the TNM Staging in Radiation Therapy for Tongue Cancer

Abstract

To evaluate correlation of volumetric staging, hematologic indices and TNM staging with efficacy of radiotherapy (RT) and chemoradiation (ChRT) for tongue cancer. The study included 61 patients (47 male, 14 female) diagnosed with tongue cancer (squamous cell carcinoma in 97% cases) aged 40-83 (median 59, mean 60) treated by RT/ChRT. Regional lymph nodes were involved in 70% of patients. Inclusion criteria were: RT or ChRT as radical therapy and no other forms of therapy. In 10 cases (16%) RT was primary choice of radical treatment. The remaining patients were disqualified from surgical approach due to comorbidities (28%), extent of the disease (39%), localization of primary lesion (10%) or lack of consent (7%). The TNM stage varied from I to IVb. Tumor and nodal volume ranged from 3.7 to 113.1cm3 and 0 to 46.1cm3, respectively. Total tumor and nodal volumes combined (GTV) were further divided into 3 risk groups with cutoff values of 15 and 70cm3. Chemotherapy (cisplatin-based) was applied in 14 patients. Total dose of 60 to 74Gy in fractions of 1.1 to 2.2Gy (combined with brachytherapy boost of 15-18Gy in 6 cases) was delivered. Blood tests were taken before RT. Statistical analysis included log-rank test, Kaplan Meier estimator, Cox proportional hazards model and Spearman’s rho. Follow-up ranged from 0 to 130 months (median 14.6 months, 4 cases without follow-up). 5-year overall survival (OS) was 37.5%. Progression of the disease was noted in 24 patients and 1-year progression free survival (PFS) defined as local, nodal and distant control was 48%. GTV divided into risk groups correlated with 1-year PFS, 3-year OS and 5-year OS (p values of 0.04, 0.04 and 0.05, respectively). Absolute values of GTV volumes correlated with 1-year PFS and 3-year OS. For TNM stage, both considered as separate groups and when comparing 0-III vs IVa-IVc stage patients no correlations with RT results were found. Neutrophils-to-lymphocyte ratio above upper or below lower quartile and higher values of hemoglobin count correlated with better 1-year PFS. There was a negative correlation between neutrophil level and treatment results. Present results suggest that for tongue cancer patients, TNM stage poorly correlates with results of RT and its prognostic value is inferior to GTV-based volumetric stage. Volumetric staging alone or combined with hematologic indices seems to be more optimal staging system than TNM.