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Ontario Cancer Facts

New cases of intra-oral cancers increasing after decades of decline

Jan 2019

Highlights

 

  • After more than 2 decades of decline, the rate of new cases of intra-oral cavity cancers increased from 2003 to 2013.
  • The increase in intra-oral cancers has been largely driven by rising rates of oropharyngeal cancer, which is tied to rising rates of human papillomavirus (HPV) infection.
  • Ontario’s school-based HPV vaccination program is expected to reduce HPV infection and, in turn, the cancers HPV causes.

 

After decreasing for over 20 years, the incidence (new cases) rate of intra-oral cancers increased by 3.4% per year from 2003 to 2013. Intra-oral cancers are a subset of oral cavity and pharynx cancers and include cancers of the tongue, mouth and oropharynx. Until 2003, the rate of these cancers had been decreasing by 0.6% per year (all changes statistically significant).

Source: Ontario Cancer Registry, 2016 (Cancer Care Ontario)

Notes:

  • Rates are per 100,000 and standardized to the age distribution of the 2011 Canadian population.
  • Incidence rates have been adjusted to adhere to the International Association of Cancer Registries (IACR) standards for counting multiple primary cancers, to allow for direct comparisons of incidence rates over time.
  • Intra-oral cavity: ICD-O-3: C01-C06, C09, and C10 (Oral cavity: ICD-O-3: C02, C03, C04, C05.0, C06; Oropharynx: C01.9, C05.1, C05.2, C09, C10).
Incidence rates for intra-oral cavity cancers, Ontario, 1981–2013
Year Male Female
1981    
1982 10.92 4.55
1983 11.27 4.86
1984 11.75 5.14
1985 11.90 5.13
1986 11.96 4.95
1987 11.45 4.60
1988 11.26 4.59
1989 11.07 4.68
1990 11.15 4.63
1991 10.76 4.71
1992 10.28 4.65
1993 9.90 4.90
1994 9.88 4.68
1995 10.47 4.53
1996 10.28 4.38
1997 10.26 4.33
1998 9.80 4.32
1999 10.10 4.37
2000 10.38 4.51
2001 10.09 4.57
2002 9.79 4.39
2003 9.61 4.37
2004 10.12 4.47
2005 10.53 4.69
2006 11.09 4.81
2007 11.19 4.75
2008 11.39 4.96
2009 11.65 5.23
2010 12.52 5.49
2011 13.15 5.49
2012 13.77 5.49
2013    

Source: Ontario Cancer Registry, 2016 (Cancer Care Ontario)

Notes:

  • Rates are per 100,000 and standardized to the age distribution of the 2011 Canadian population.
  • Incidence rates have been adjusted to adhere to the International Association of Cancer Registries (IACR) standards for counting multiple primary cancers, to allow for direct comparisons of incidence rates over time.
  • Intra-oral cavity: ICD-O-3: C01-C06, C09, and C10 (Oral cavity: ICD-O-3: C02, C03, C04, C05.0, C06; Oropharynx: C01.9, C05.1, C05.2, C09, C10).

The incidence of oral cavity and pharynx cancers also increased from 2003 to 2013, but the rate of increase for intra-oral cancers was almost twice as high. The increase in intra-oral cancers was greater in males (whose rate increased by 3.8% per year) than females (whose rate increased by 2.6% per year).

The major risk factors for intra-oral cancers are tobacco and alcohol use. Human papillomavirus (HPV) is also a major risk factor for oropharyngeal cancer, but not the other types of intra-oral cavity cancers. While the decrease in intra-oral cancers from 1981 to 2003 was likely driven by a decrease in tobacco use, the increase since 2003 appears to be a result of rising rates of HPV infection. Oropharyngeal cancer incidence increased at a greater rate than other intra-oral cancers between 2003 and 2013. The rise in HPV infection has been linked to changing patterns in sexual behaviour, particularly an increased number of sexual partners and oral sex.

It usually takes years after being infected with HPV for oropharyngeal cancer to develop, and not all oropharyngeal cancers are caused by HPV. While population-level Ontario data on the incidence of oropharyngeal cancers caused by HPV has only just begun to be collected, research has shown that the incidence of oropharyngeal cancers caused by HPV has increased in Canada since 2000. However, Ontario’s school-based HPV vaccination program is expected to reduce HPV in the population over the coming decades, which will likely reduce the burden of HPV-associated cancers.

References

  1. Ryerson AB, Peters ES, Coughlin SS, et al. Burden of potentially human papilloma-virus associated cancers of the oropharynx and oral cavity in the US, 1998–2003. Cancer. 2008;113:2901–19.
  2. Mehanna H, Beech T, Nicholson T, et al. Prevalence of HPV in oropharyngeal and non-oropharyngeal head and neck cancer-systematic review and meta-analysis of trends by time and region. Head Neck. 2011;35:747–55.
  3. Rettig E, Kiess AP, Fakhry C. The role of sexual behavior in head and neck cancer: implications for prevention and therapy. Expert Rev Anticancer Ther. 2014;15(1):35–49.
  4. Habbous S, Chu KP, Lau H, et al. Human papillomavirus in oropharyngeal cancer in Canada: analysis of 5 comprehensive cancer centers using multiple imputation. CMAJ. 2017:189(32);E1030–40.
  5. Nichols AC, Palma DA, Dhaliwal SS, et al. The epidemic of human papillomavirus and oropharyngeal cancer in a Canadian population. Curr Oncol. 2013;20(4):212–9.