Definitions

Epidemiology is the study of disease distribution and determinants in different populations. This information is applied to develop preventative measures or guide management in those who have already acquired the illness.

Incidence refers to the occurrence of new cases of disease in a population over a specified period of time.

Head and neck cancer (HNC) is a heterogeneous group of malignancies involving the upper aerodigestive tract. Most commonly, these are squamous cell carcinomas arising from the mucosal lining of the various head and neck sub-sites including the oral cavity, nasopharynx, oropharynx and larynx/hypopharynx.  

Incidence

• The estimated number of new cases of head and neck cancers in the United States (U.S.) in 2018 is 64,990 with an estimated 13,740 deaths.¹ Globally, the estimated number of new cases per year is 686,328 making it the seventh most common cancer in the world. ^2-3 It is estimated that by 2020, a growing and aging population will result in doubling of these numbers to 1 million new cases and over half a million deaths per year.³

^​

• The incidence of head and neck cancer varies widely based on geographic region as shown in the table below.⁴  An important influence in the geographic variability in HNC incidence is related to the differential exposure to the major risk factors of HNC.⁴

Risk Factors for HNC

• Tobacco use: There is a four-fold to ten-fold increased risk of developing HNC among tobacco users which is dose dependent.⁵ Alcohol synergistically increases the risk of HNC. Smokeless tobacco increases the risk of oral cavity squamous cell cancer by four fold in those with at least 10 years of use compared to never users.⁵ Tobacco cessation reduces the risk of HNC as soon as 1-4 years after quitting and reaches the level of never smokers after 20 years.³

^​

• Alcohol: As noted above, alcohol synergistically increases the risk of HNC in combination with tobacco and together account for 75% of the disease.^3,6 In those who are never smokers, significant alcohol use (defined by three or more drinks per day) has been associated with increased risk of HNC.⁶

^​

• Human Papilloma Virus (HPV): HPV is a small non-enveloped double stranded circular DNA virus with numerous strains. Through epidemiological and molecular studies, HPV 16, and to a lesser extent HPV 18, have been recently identified as an important causal factor in the development of HNC, particularly in the oropharynx. HPV-related HNC is more frequently seen in white males who are not smokers, drinkers, or immunosuppressed and have improved prognosis compared to non HPV-related HNC.^4-6 They tend to be younger by a median of 4-10 years and have higher socioeconomic status.^5,7 Risk factors for HPV include oral HPV infection, increasing lifetime number of genital and oral sexual partners, younger age at first intercourse, history of genital warts, and lack of condom use.⁹

^​

• Gender: There is a 2-fold to 9-fold higher incidence of HNC in men compared to women⁴. This is likely related to the higher rates of tobacco use among men.⁶

• Age: The risk of HNC increases with age and the median age at diagnosis is in the late sixth and seventh decades of life.⁵

• Other known risk factors include betel quid use, immune suppression, poor oral hygiene, occupational exposures, EBV (nasopharyngeal carcinoma), low socioeconomic status, and cancer susceptibility syndromes (e.g. Fanconi’s anemia).⁶ 

Trends in HNC incidence in the United States

• Temporal: Incidence trends of HNC across countries and over time are strongly influenced by patterns of tobacco use.^4-5 In the U.S., tobacco use peaked in the 1940s-1960s followed by increases in the incidence of HNC. A subsequent decline in smoking prevalence was followed by a decline in the rate of HNC beginning in the 1990s.⁵ From 2002-2012, the incidence of HNC decreased by 0.22% per year.⁷  In contrast, the incidence of HPV associated cancer over the same time period increased by 2.5% per year.⁷ 

• Sub-sites: Trends by sub-site show significant decreases in the incidence of lip, oral cavity, hypopharyngeal, and laryngeal cancer between 1974-1999 whereas the incidence for nasopharyngeal and oropharyngeal carcinoma remained stable over the same time period.⁴ Data from subsequent years (1998 – 2004) showed a 28% increase in oropharyngeal cancers which is attributable to the increase in HPV positive tumors. The incidence of HPV positive tumors increased by 225% while HPV negative tumors decreased by 50% over the same time period.⁸

^​

• Gender: The incidence of HNC from 2002-2012 decreased by 0.29% per year in men and 0.38% in women. For oropharyngeal cancers, there was an increased incidence in men of 2.89% per year but only 0.57% in women with a statistically significant difference between genders.⁷

^​

• Age: There was a significant decreasing trend of HNC by 1.35% per year in patients 40-49 years old from 2002-2012. In HPV related cancer there was a significant increase in incidence in the 50-59 age group and those older than 60 in the same time period.⁷

^​

• Race: Historically, HNC was higher among blacks than whites in the United States, but the incidence has been declining and is now higher in whites (15.5 per 100,000 compared to 14.8 per 100,000).⁵ This is thought to be in part related to the increase in HPV associated HNC seen in white males.

Trends in HNC incidence globally

• Geographic: The incidence rates for HNC have increased in many European countries (Belarus, the Czech Republic, the UK, Denmark, Estonia, Finland, Latvia, Norway and Sweden). Incidence rates are unchanged or show minor decreases in Canada, United States, and many Asian countries.² 

• Sub-sites: The following trends categorized by sub-site reflect incidence comparisons between the years of 1983-1987 and 1998 – 200210.
  • Oral cavity: Oral cavity cancers have increased in both men and women in the Czech Republic, Slovak Republic, Estonia, Denmark, Finland, United Kingdom, and Japan.¹⁰ There was a decreased incidence in China, India, Thailand, Philippines, Canada, and the U.S. Despite the decrease noted in India, the incidence of oral cavity cancer there remains highest at ~15 per 100,000.¹⁰
  • Oropharynx: Oropharyngeal cancers have increased among men and women in Belarus, Czech Republic, Denmark, Finland, Norway, Sweden, and United Kingdom while showing a decrease in India (Mumbai) and China. In Germany, Japan, Canada and the U.S., oropharyngeal carcinoma incidence increased among men only. The oropharyngeal cancer rates are highest among men in France at ~9 per 100,000.¹⁰
  • Hypopharynx/larynx/other: Incidence rates increased in the United Kingdom among men and women and decreased in Finland, Italy, China, India, Singapore, Thailand, Canada, U.S., Costa Rica, and Australia. Rates were highest among men in France and Spain at ~23 per 100,000.¹⁰

^​

Statistics on Survival & Mortality

• Mortality and Survival of HNC in the US by sub-site (adapted from Rettig et al.⁵)

• Globally, incidence and mortality trends show an increase in both developed and developing countries with only the USA demonstrating falling mortality rates.²  The table below shows age standardized mortality rates (ASMR) per 100,000 for males and females based on geographic region.²

^​