Artificial intelligence in dentistry: Harnessing big data to predict oral cancer survival

Table 2 List of all 10 variables included in the final machine learning model building and validation

Variables	Variable description
Age at diagnosis	This data item represents the age of the patient at diagnosis for this cancer. The code is three digits and represents the patient’s actual age in years
Year of diagnosis	The year of diagnosis is the year the tumor was first diagnosed by a recognized medical practitioner, whether clinically or microscopically confirmed
Month of diagnosis	The month of diagnosis is the month the tumor was first diagnosed by a recognized medical practitioner, whether clinically or microscopically confirmed
Primary site	This data item identifies the site in which the primary tumor originated. See the International Classification of Diseases for Oncology, 3rd Edition (ICD-O-3)[18] for topography codes. The decimal point is eliminated
CS tumor size	Information on tumor size. Available for 2004-2015 diagnosis years. Earlier cases may be converted and new codes added which weren't available for use prior to the current version of CS. For more information, see http://seer.cancer.gov/seerstat/variables/seer/ajcc-stage[19]
CS extension	Information on extension of the tumor. Available for 2004-2015 diagnosis years. Earlier cases may be converted and new codes added which weren't available for use prior to the current version of CS. For more information, see http://seer.cancer.gov/seerstat/variables/seer/ajcc-stage[19]
CS lymph nodes eval	Available for 2004-2015, but not required for the entire timeframe. Will be blank in cases not collected. For more information, see http://seer.cancer.gov/seerstat/variables/seer/ajcc-stage[19]
Derived AJCC stage group	This is the AJCC “Stage Group” component that is derived from CS detailed site-specific codes, using the CS algorithm, effective with 2004-2015 diagnosis years. See the CS site-specific schema for details (http://seer.cancer.gov/seerstat/variables/seer/ajcc-stage)[19]
RX Summ-surg prim site	Surgery of primary site describes a surgical procedure that removes and/or destroys tissue of the primary site performed as part of the initial work-up or first course of therapy
Site recode ICD-O-3/WHO 2008	A recode based on primary site and ICD-O-3 Histology in order to make analyses of site/histology groups easier. For example, the lymphomas are excluded from stomach and Kaposi and mesothelioma are separate categories based on histology. For more information, see http://seer.cancer.gov/siterecode/icdo3_dwhoheme/index.html[20]

CS: Coding System; AJCC: American Joint Committee on Cancer; ICD-O-3: International Classification of Diseases for Oncology, 3rd ed; WHO: World Health Organization.