Purpose

We sought to examine prognostic and therapeutic implications, including cost-effectiveness, of elective neck dissection in the management of patients with clinically-determined T1N0 oral tongue carcinoma.

Materials and methods

A retrospective review of patients with cT1N0 oral tongue squamous cell carcinoma who underwent surgical extirpation of primary tumor, with or without elective neck dissection, at UCLA Medical Center from 1990 to 2009 was performed. Cox proportional hazards regression was used to assess effects of variables on time to first loco-regional recurrence. A healthcare costs analysis of elective neck dissection was performed by querying the SEER-Medicare linked database.

Results

Of the 123 patients identified with cT1N0 squamous cell carcinoma of the oral tongue, 88 underwent elective neck dissection at the time of tumor resection while 35 did not. For all patients, disease-free survival at 3, 5, and 10 years was 93%, 82%, and 79%. Of the 88 patients undergoing elective neck dissection, 20 (23%) demonstrated occult metastatic disease. Male gender, tumor size, perineural invasion, and occult metastatic disease were individually associated with higher rates of loco-regional recurrence. There was no significant difference in loco-regional recurrence between those who underwent elective neck dissection and those who did not (HR=0.76, p=0.52). On cost analysis, neck dissection was not associated with any significant difference in Medicare payments.

Conclusions

The high rate of occult metastasis (23%) following elective neck dissection, which did not confer additional healthcare costs, leads to the recommendation of elective neck dissection in patients with cT1N0 oral tongue squamous cell carcinoma.

The genetics of cortical arealization in youth is not well understood. In this study, we use a genetically informative sample of 677 typically developing children and adolescents (mean age 12.72 years), high-resolution MRI, and quantitative genetic methodology to address several fundamental questions on the genetics of cerebral surface area. We estimate that >85% of the phenotypic variance in total brain surface area in youth is attributable to additive genetic factors. We also observed pronounced regional variability in the genetic influences on surface area, with the most heritable areas seen in primary visual and visual association cortex. A shared global genetic factor strongly influenced large areas of the frontal and temporal cortex, mirroring regions that are the most evolutionarily novel in humans relative to other primates. In contrast to studies on older populations, we observed statistically significant genetic correlations between measures of surface area and cortical thickness (r G = 0.63), suggestive of overlapping genetic influences between these endophenotypes early in life. Finally, we identified strong and highly asymmetric genetically mediated associations between Full-Scale Intelligence Quotient and left perisylvian surface area, particularly receptive language centers. Our findings suggest that spatially complex and temporally dynamic genetic factors are influencing cerebral surface area in our species.SIGNIFICANCE STATEMENT Over evolution, the human cortex has undergone massive expansion. In humans, patterns of neurodevelopmental expansion mirror evolutionary changes. However, there is a sparsity of information on how genetics impacts surface area maturation. Here, we present a systematic analysis of the genetics of cerebral surface area in youth. We confirm prior research that implicates genetics as the dominant force influencing individual differences in global surface area. We also find evidence that evolutionarily novel brain regions share common genetics, that overlapping genetic factors influence both area and thickness in youth, and the presence of strong genetically mediated associations between intelligence and surface area in language centers. These findings further elucidate the complex role that genetics plays in brain development and function.