Review
Comparison of primary care doctors and dentists in the referral of oral cancer: a systematic review

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Abstract

Oral cancer is referred to specialists by both general practitioners (GPs) and dentists, with varying proportions reported in different studies. However, some have noted that dentists more commonly refer oral cancer in the absence of patient-perceived symptoms and may refer at an earlier stage. Unfortunately, approximately half the UK adult population do not receive regular dental care. We have conducted a systematic review of studies that compare GPs and dentists in the referral of oral cancer and have focused on three aspects: the proportion of diagnosed oral cancers, stage on presentation, and delay. Searches of the databases Medline, Embase, Scopus, Google Scholar, Web of Science, and CINAHL, together with additional searches of reference lists, authors, and conference proceedings, found 22 studies from 10 countries, which included a total of 4953 oral cancers. The percentage of medical referrals ranged from 13% to 86%; dental referrals ranged from 15% to 80%. Random-effects meta-analysis indicated a combined relative risk of medical referral to dental referral of 1.36 (95% CI: 0.99 to 1.86). For UK-based studies, the relative risk was also 1.36 (95% CI: 1.05 to 1.76). There was considerable heterogeneity for all studies and for a subgroup of UK studies: I296.4% (95% CI 95.4 to 97.1) and 81.0% (95% CI 63.3 to 90.1), respectively. Several studies showed a lower stage for dentally-referred cancers; the combined risk for dentists and GPs referring early (stages 1 and 2) disease was 1.37 (95% CI: 1.17 to 1.60), and one cause may be the much higher number of cases referred by dentists in the absence of symptoms. No studies showed a significant difference in delay. Oral cancer is referred by both GPs and dentists, typically about 50% and 40%, respectively, although there is a wide range, probably depending on local circumstances. Both groups require skills in oral examination, recognition of lesions, and knowledge of the risk factors. Effectively, regular dental attenders are a select group that is regularly screened for oral cancer, and it is likely that screening is not delivered to those with the highest risk. We suggest that further work is required on how to access high-risk individuals both for possible screening and preventive interventions.

Introduction

Oral cancer is the sixth most common cancer in the world,1 and approximately 6500 cases are diagnosed/year in the UK.2 The incidence of oral cancer is projected to rise by 33% in the UK from 2014 to 2035, with 20 cases/100 000 people in 2035.3

Disease stage at presentation has a major influence on survival,4, 5 and cancers that are larger and have spread to the lymph nodes have a much poorer prognosis. Two-year crude survival for stage 1 (early) disease is approximately 90% whilst for stage 4 (advanced) disease it is less than 50%.6 Early diagnosis is clearly very important. Unfortunately, approximately 50% of oral cancers present at advanced stage 3 or 4, despite the accessibility of the mouth for relatively easy examination.7

Oral cancer is unique amongst malignancies in that it is referred to specialist care by both primary care doctors and dentists, which is unlikely for other types of cancer.8 Proportions referred by each group vary across studies. A study of 200 oral cancer patients in the UK2 reported that 57% were referred by their GP, 32% by their dentist, 2% via a hospital emergency department, and 9% were unknown. In a Canadian series, 65% of oral cancers were referred by a dentist.9 In the UK, both medical and dental primary-care practitioners are provided with a list of “guideline” symptoms and signs to assist in the referral of oral cancer.10, 11, 12 Several authors have noted the importance of utilising these guidelines in conjunction with a thorough history and examination – the principles of good medical practice are paramount.10 One study,13 however, found that only 18% of family physicians carried out an examination of the mouth in half their patients.

Further differences between the referrals from each group of practitioners have been reported. An American study9 reported that 47% of dentist-diagnosed oral cancers were identified during a non-symptom-driven visit whilst all medical referrals were symptom-driven. In the same study, the average clinical and pathological stage of the non-symptom diagnoses were significantly lower (1.7 and 1.6, respectively) than those of lesions detected during a symptom-directed examination (2.6 and 2.5, respectively). It would seem, therefore, that routine examination of the oral soft tissues at a dental check-up is important in the early diagnosis of oral cancer, and dental practitioners are in a good position to carry out routine soft tissue examinations of the oral cavity.14 However, English NHS data for 2017-18 indicate that only 50.9% of adults had visited an NHS dentist in the previous two years15 and it is probable that those at highest risk of oral cancer are least likely to attend regular consultations.16

The overall aim of this systematic review was to compare primary care doctors and dentists in the referral of oral cancer, focusing on three main objectives: the proportion of diagnosed cancers that were referred by each profession, differences in stage on presentation for referrals from each profession, and differences in delay.

Section snippets

Types of studies

Studies that examined the referral of oral cancer and compared GPs and dentists (that is, the study included data for both professions) were considered for this review. They were required to include one or more of the following outcomes:

  • Proportion/percentage of diagnosed cancers referred by each profession

  • Stage on presentation for each profession

  • Presentation delay in relation to each profession

Studies were required to report on diagnosed oral cancers, rather than suspected cancer referrals.

Search outcome

A total of 895 papers were identified by electronic searches, and nine from other sources. Scrutiny of abstracts found 32 studies on the referral of oral cancer from primary to secondary care. Of these, 22 included data on the referral of oral cancer by primary care doctors and dentists (Fig. 1).

Description of included studies

A total of 22 studies were included in the review (Table 1).2, 9, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40 All of them included data on the proportion (percentage)

GP and dentist referrals

This review confirms that both primary care doctors and dentists have an important role in the referral of oral cancer to specialist services. Meta-analysis of GP/dentist referral risk ratios indicated that approximately 14 oral cancers were referred from GPs for every 10 from a dentist, although there was considerable variation between studies undertaken in different countries – and indeed between those in the same country. Subgroup analysis of UK studies similarly demonstrated varying

Conflict of interest

Langton: none; Cousin: none; Pluddemann: NIHR grants and occasional teaching expenses; Bankhead: Funding from NIHR, PGfAR, CRUK, Oxford Biomedical Research Centre.

Ethics statement/confirmation of patients’ permission

Not required as this study is a systematic review. No identifiable patient material used.

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