KENYA NATIONAL CANCER SCREENING GUIDELINES I 75
ORAL CANCER SCREENING
• Incidence of oral cancer is increasing globally particularly in
• Early diagnosis of oral cancer has a statistically significant impact on
• Risk factors of oral cancer include habits such as consumption
of tobacco, alcohol and betel nut
• Opportunistic screening targeting all individuals at risk of developing
the disease is recommended
• A combination of visual and analytical screening gives a high positive predictive value for oral cancer justifying the screening of tobacco users
• Training of personnel at different levels of the health system
in visual and analytical screening of oral cancer is recommended
• Incorporation of monitoring and evaluation in the referral
chain ensures responsiveness of the health system to oral cancer
Oral cancer is by definition any malignancy
arising from oral tissues; pharynx and salivary
glands. The global incidence of oral cancer is
354,864 cases where mortality attributed to
this condition is 177,384 deaths per annum
(GLOBOCAN, 2018). Over 90% of oral cancers
are squamous cell carcinomas (OSCC), with the
remaining fraction consisting of varying per-
centages of lymphomas, sarcomas and adeno-
carcinomas (Ibukunle et al, 2018; Idris et al 2016;
Monteiro et al, 2016). It predominantly occurs
in male patients in the fifth and sixth decades of
life. Modifiable risk factors include habits such as consumption of tobacco, alcohol and
betel nut. Incidence varies regionally with the prevalence of these high-risk habits, with
statistics as high as 40% in parts of Asia (Chuang et al, 2017).
Oncogenic strains of the human papilloma virus (HPV) are aetiologically associated with oral cancer (Argiris, 2008). As an HPV-associated malignancy, the incidence of oral cancer increases exponentially in patients infected with the human immunodefciency virus (HIV) together with cancers of the urogenital systems (Khot et al, 2016). OSCC is ranked as the third most common head and neck malignancy for patients with HIV-infection worldwide, after Kaposi’s sarcoma and non-Hodgkin’s lymphoma (Heigenz, 2005). Mucosal diseases such as leukoplakia, erythroplakia, lichen planus and oral submucous fbrosis have the potential to progress into invasive OSCC.
The incidence of oral cancer varies regionally with only about 4% of all cancers in developed countries but as high as 40% in parts of India and Sri Lanka (Ferlay et al, 2015). A comparison of sub-Saharan countries demonstrates relatively high incidences and mortality due to oral cancer in Kenya. According to the GLOBOCAN data (Bray et al, 2018), Kenyan patients with oral cancer record high mortality rates as compared to survival rates globally (Figure 1). Data from the Nairobi Cancer Registry (Korir et al, 2008) showed that 4.9% of the disease burden was attributable to oral cancer (ASR 8.4 per 100,000). In males, oral cancer accounted for
10.24% of malignancies while in females it contributed to 4.3%. Butt and co-authors (2008), reported OSCC as the second most common malignancy affecting HIV-infected patients in Kenya after Kaposi’s sarcoma. Majority of the patients present in Tumor- Node- Metastasis (TNM) stages 3 and 4, resulting in poor prognosis after treatment (Butt, 2008).
Figure 7: Incidence and mortality estimates for lip and oral cavity cancer in sub-Sa- haran Africa (IARC I Globocan 2078)
RATIONALE FOR SCREENING
Screening can be defined as the process of examining or applying a rapid test to a pop-
ulation to identify a group at risk from a disease. Evidence of the utility of screening may
be derived from Asian countries where the relatively high incidences of oral cancer de-
manded innovative interventions. In India, a seminal randomized trial of visual screen-
ing for oral cancer was conducted for a cohort of 95,000 patients (Sankaranarayanan et
al, 2005). A similar number of people in the control group did not undergo screening
and were monitored for up to 12 years for mortality by community health workers. De-
spite the fact that only 63% of people found with lesions had the recommended further
assessment, death from oral cancer in users of tobacco or alcohol was reduced by 34%
which was statistically significant.
Taiwan scaled up to implement a nationwide program for tobacco and betel nut users incorporating over 2 million participants since 2004 (Chuang et al, 2017). This program resulted in a reduction in the number of patients presenting with TNM stages III and IV oral cancers and 24% reduction (95% CI, 3%-40%) in oral cancer mortality. Increased di- agnostic acumen resulted in treatment seeking in TNM stages I and II, with better prog- noses. The WHO guidelines recommend screening for early detection of oral cancers.
WHO SHOULD BE SCREENED AND WHEN?
The most effective approach to ensure early diagnosis of oral cancers in a resource- lim-
ited setting is to offer opportunistic mass screening, targeting all individuals at risk of
developing the disease (NSC, UK, 2018). The criteria for annual screening should simply
be a history of consumption of tobacco and/ or exposure to any other risk factor for oral
SCREENING AT VARIOUS HEALTHCARE LEVELS
Oral cancer screening is fairly straightforward because apart from the tumors extending
into the pharynx, most lesions are easily accessible and those at risk can be easily identi-
fied (Chuang et al, 2017). Visual screening can be integrated into primary health care for
a few dollars, while analytical screening remains the preserve of either a cytologist, an
anatomical pathologist or an oral pathologist. There is a need to develop a multi sectoral
approach that integrates tobacco and alcohol control as part of health education.
Oral cancer screening is fairly straightforward because apart from the tumors extending into the pharynx, most lesions are easily accessible and those at risk can be easily identi- fied (Chuang et al, 2017). Visual screening can be integrated into primary health care for a few dollars, while analytical screening remains the preserve of either a cytologist, an anatomical pathologist or an oral pathologist. There is a need to develop a multi sectoral approach that integrates tobacco and alcohol control as part of health education.
Table 7: Health facilities and staff cadres for oral cancer screening
|1||Community||Community Health care worker||Oral Health awareness|
|2||Dispensary||Nurses||Oral Health awareness|
|3||Health Centres||Nurses||Oral Health awareness
Mobilization Visual screening Sample collection
|Community Oral Health Officer|
|4||Sub-county||Nurses||Oral Health awareness
Sample collection and
|Community Oral Health Officer|
SCREENING TESTS TO BE DONE
The clinician should conduct visual and analytical screening in the following sequence
(Huber et al, 2014):
1. VISUAL EXAMINATION
a) Extraoral examination – inspect the head and neck region for asymmetry or swelling. Palpate the submandibular, neck and supraclavicular lymph nodes paying attention to size, number, tenderness and mobility. Inspect and palpate the lips and perioral tissues for abnormalities.
b) Intraoral examination – systematically inspect and palpate all oral soft and
bony tissues paying attention to the high-risk sites for the development of oral
cancer including the lateral and ventral aspects of the tongue; floor
of the mouth; labial mucosa; cheek; soft palate; pharynx, tonsils, maxilla and
c) Lesion inspection – Lesions which persist for more than 14 days should be
referred for further investigation. Evaluate the specific characteristics of each
lesion with particular attention to the size, colour, texture and contour. Any
white, red, ulcerated and /or indurated lesions are documented.
d) Documentation – at the time of initial assessment and each re-evaluation
appointment, it is recommended that a clear record should be maintained.
2. OPTIONAL SCREENING ADJUNCTS
Adjunctive visual tools can enhance contrast between the clinical lesion and the adjacent normal oral tissue. Techniques include toluidine blue staining and direct fluorescence vi- sualization. Mucosal changes stain positively with the application of toluidine blue dye or show loss of fluorescence in premalignant and malignant lesions. These methods, howev- er, do not give a definitive diagnosis (Zhang et al, 2005). Toluidine blue dye is itself muta- genic and, therefore, its use is restricted.
Direct fluorescence involves intraoral application of a hand-held device that emits a cone of blue light which excites various molecules within mucosal cells, causing them to absorb the light energy and re-emit it as visible fluorescence (Lane et al, 2006). Healthy oral tissue emits a pale green fluorescence while altered tissues which attenuate the passage of light appear dark brown or black (loss of fluorescence).
Imaging is used as an adjunct for diagnosis for patients with clinical lesions that have a high
index of suspicion. Plain X-rays, CT Scans and MRI are used to investigate the extent of the
tumor, nodal involvement and metastasis.
4. DIAGNOSTIC BIOPSY
Brush biopsy uses a round stiff bristle brush to collect cells from the surface layers of a le-
sion by vigorous abrasion. The cells collected are transferred to a microscope slide to iden-
tify abnormal cells. Cytological studies tend to be technique sensitive and require trained
personnel for accurate interpretation.
Table 2: Diagnositic sequence for early detection of oral cancer
|TYPE OF TEST||PERSONNEL|
|Visual screening||Nurse, Clinical officer, Community oral health officer|
|Exfoliative||Sample collection: Nurse, clinical/ medical/ dental officers
Analysis: Cytologist, pathologist
|Incision biopsy||Sample collection: Dental officer, Maxillofacial surgeon
SCREENING ALGORITHM FOR OSCC
Imaging & Analytical screening
Figure 3: Screening algorithm for OSCC
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