Poor oral hygiene contributes to head, neck cancer risk

Maintaining good oral hygiene may lead to a modest reduction in the risk for head and neck cancer, according to retrospective study results published in Annals of Oncology.

Research has suggested poor oral hygiene could increase risk for head and neck cancer; however, the causal role of oral hygiene in development of head and neck cancer has been inconclusive.

Dana Hashim, MD, postdoctoral fellow in the department of preventive medicine at Icahn School of Medicine at Mount Sinai, and colleagues sought to evaluate head and neck cancer risk associated with five oral hygiene indicators — wearing dentures, missing teeth, gum disease, tooth brushing and dentist visits.

The researchers accessed data from 8,925 patients with head and neck cancer enrolled in 13 trials conducted by the International Head and Neck Cancer Epidemiology Consortium. The analysis also included data from 12,527 cancer-free controls.

The majority of patients had oral cavity cancer (n = 2,858); other cancer subtypes included oropharynx (n = 2,402), hypopharynx (n = 738), larynx (n = 2,086), and oral cavity/pharynx not otherwise specified (n = 841).

The majority of studies (n = 12) used face-to-face questionnaires to obtain oral hygiene data; one study obtained data from questionnaires administered by dentists.

The study defined good oral hygiene as not wearing dentures; having no gum disease or bleeding; fewer than five missing teeth; daily tooth brushing; and one or more annual dentist visits.

The researchers observed inverse associations for any head and neck cancer with having fewer than five missing teeth (OR = 0.78; 95% CI, 0.74-0.82); visiting the dentist annually (OR = 0.82; 95% CI, 0.78-0.87); brushing teeth at least once a day (OR = 8.3; 95% CI, 0.79-0.88); and not having gum disease (OR = 0.94; 95% CI, 0.89-0.99).

Wearing dentures did not correlate with an increased risk for head and neck cancer.

Factors inversely associated with oropharyngeal and pharyngeal cancers included fewer than five missing death, daily tooth brushing and regular dentist visits. For hypopharynx cancers, inverse associations included daily tooth brushing and regular dental visits.

The risk for laryngeal cancer was inversely associated with fewer than five missing teeth, wearing dentures, regular dentist visits and daily tooth brushing. However, these factors were attenuated when all five variables were included in a regression analysis.

The researchers calculated a population attributable fraction for having two or fewer good oral hygiene indicators of 8.9% (95% CI, 3.3-14) for oral cavity cancer and 5.4% (95% CI, 0.36-10) for all head and neck cancer.

Study limitations included the researchers’ inability to control for factors that may potentially influence oral hygiene, such as diabetes management or the presence of inflammatory oral conditions, as well as the potential for recall bias inherent in case–control studies.

“Good oral hygiene is associated with lower risk [for] head and neck cancer,” Hashim and colleagues wrote. “Improvements in oral hygiene by increasing oral hygiene literacy, particularly for annual dentist visits and daily tooth brushing, may be protective against head and neck cancer, though the extent of risk reduction is modest.” – by Cameron Kelsall

Disclosure: The researchers report no relevant financial disclosures.