Methods
The data for this review was obtained from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute (NCI). SEER contains data for 34.6% of the United States population obtained from population-based cancer registries (19). SEER data is de-identified and contains information on patient demographics, primary tumor site, tumor morphology, stage at diagnosis, treatment and relevant comorbidities (19). Comprehensive patient data from 1975-2016 was requested from SEER 18 Regs Research Incidence Data and analyzed by a statistician. For patients with multiple HNC malignant tumors, their first primary tumor was chosen as the record to analyze.
HNC incidence data was obtained dating back to 1975 for the following areas: San Francisco-Oakland SMSA, Connecticut, metropolitan Detroit, Hawaii, Iowa, New Mexico, Utah, metropolitan Atlanta. Data dating back to 1992 was obtained for the following areas: San Jose-Monterey, Los Angeles, Alaska, rural Georgia. Data dating back to 2000 was obtained for California, Kentucky, Louisiana, New Jersey and greater Georgia. All data contributes to the proportion of patients with HNC in subsites of interest. Data was broken down into respective U.S. regions including West, Northeast, Midwest, Southwest and Southeast in order to visualize regional differences in cancer prevalence. Additional demographic factors such as gender and race were also included.
Primary head and neck tumor data was organized into cancers of the oral cavity, oropharynx, larynx and hypopharynx. Oral cavity cancers include primary tumors of the external upper lip, external lower lip, external lip not otherwise specified (NOS), mucosa of upper lip, mucosa of lower lip, mucosa of lip NOS, commissure of lip, overlapping lesion of lip, lip NOS, skin of lip NOS, dorsal surface of tongue, border of tongue, ventral surface of tongue, anterior ⅔ of tongue, overlapping lesion of tongue, tongue NOS, upper gum, lower gum, gum NOS, anterior floor of mouth, lateral floor of mouth, overlapping lesion of floor of mouth, floor of mouth NOS, hard palate, overlapping lesion of palate, palate NOS, cheek mucosa, vestibule of mouth, overlapping lesion of other/unspecified mouth. Cancers of the oropharynx encompass primary tumors of the base of tongue, lingual tonsil, soft palate, uvula, retromolar area, tonsillar fossa, tonsillar pillar, overlapping lesion of tonsil, tonsil NOS, vallecula, lateral wall of oropharynx, posterior wall of oropharynx, overlapping lesion of oropharynx, oropharynx NOS. Cancers of the larynx encompass primary tumors of the anterior surface of the epiglottis, glottis, supraglottis, subglottis, laryngeal cartilage, overlapping lesion of larynx, larynx NOS. Cancers of the hypopharynx encompass primary tumors of pyriform sinus, postcricoid region, aryepiglottic fold, posterior wall of hypopharynx, overlapping lesion of hypopharynx, hypopharynx NOS, pharynx NOS, waldeyer’s ring and overlapping lesion of lip/oral cavity/ pharynx.
HNC data dates as far back as 1975 in the SEER database. HNC incidence was broken down into 10-year intervals from 1975-1984, 1985-1994, 1995-2004 and 2005-2016. Specific age cohort data was recorded for the last four decades for individuals 0-39, 40-59 and 60+ years of age. For study purposes, patients 0-39 years old were considered “young”, patients ranging from 40-59 years of age were considered “middle-aged” and patients in the 60+ age group were considered “elderly”. Data was broken down by decade and age cohort for each primary tumor site. Data for primary tumor site and mean/median age of diagnosis were also included for each decade. Additional data for the incidence of each of the four HNC subsites over time was also collected.