Oral Cancer: Diagnosing earlyJanuary 6, 2020
Oral cancer is the third most common cancer in India. The country has the ninth highest incidence of oral cancer in the world (age-standardized incidence 7.2 per 100 000). The estimated national mortality is 6.7 per 100 000 in men and 3.0 per 100 000 in women. Although 5-year survival is between 54.3% and 60.2% for localized cancers of the mouth, it can be as low as 3.1–3.3% in advanced stages in India. Early detection and treatment allow effective treatment with better outcomes with less morbidity at a less cost.
Difference between screening and early diagnosis
A screening programme is an on-going process of examination and referral, applied to a defined population at set intervals, case-finding or early detection, which is usually, a one-off process of clinical examination aimed at diagnosing specific lesions. Screening is defined as: the application of a test or tests to people who are apparently free from the disease in question in order to sort out those who probably have the disease, from those who probably do not. Conversely, case-finding refers to the application of a diagnostic test or method to patients with abnormal signs or symptoms in order to establish a diagnosis.
Population screening, Opportunistic screening and
high-risk group screening
A population as a whole could be screened, or a segment of the population visiting any health facility could be selectively targeted. High-risk group screening targets individuals with a high risk of tobacco and alcohol consumption, which are the established risk factors for oral cancer.
A good model for screening and early detection
Oral cancer with known risk factors, a strong association with established premalignant lesions, long and detectable preclinical phase, easily detectable premalignant lesions and the ease of accessibility, is a good model for screening and early detection. Visual screening of the oral cavity is simple, non-invasive, acceptable, affordable, safe, feasible screening test. Early, localized oral cancers can be effectively treated and cured with single-modality treatments.
Conventional Oral Screening is a proven method of oral cancer screening. It is a systematic visual and physical examination of the intraoral mucosa under bright light. Careful inspection and digital palpation of the neck is also done. Reported sensitivity and specificity are 40-93% and 50-99% respectively. Though visual screening can effectively identify a malignant lesion in high-risk patients, it may not help in identifying lesions that are highly susceptible to malignancy.
Trivandrum Oral Cancer Screening study
It was a cluster-randomized trial conducted in 13 panchayats of Trivandrum district with its results reported in 2005. The study compared “conventional oral screening” to “no screening.” The study showed a significant, 34% reduction in oral cancer mortality among the high-risk group of tobacco/alcohol users after three rounds of oral/visual screening. A subsequent study has shown that it is also cost-effective. Oral cancer screening by visual inspection was performed for under US$6 per person (less than a dollar annual cost). The incremental cost per life-year saved was US$835 for all individuals eligible for screening and US$156 for tobacco or alcohol users.
Oral Cancer Screening is still not adopted as a national programme. Very few countries have tried to adopt oral screening for cancer as a national programme. It is not clear why, even with so much country-specific evidence favoring its adoption, it has not been adopted in India.
Patient-level barriers like financial factors, stigma and fear, as well as system-level barriers like shortage of facilities and a shortage of staff may have contributed.
Newer adjuncts in screening
Optical imaging-based systems, including Optical Coherence Tomography, Chemiluminescence and Tissue Autofluorescence, have been reported. Nano particle-based immunosensors and salivary biomarkers are also being studied. None of these adjuncts has proven to be beneficial for screening in a community setting. Much of the research on these techniques are in the gadget discovery mode in a clinical setting in patients lesions, as against asymptomatic individuals. The sensitivity and specificity of these adjuncts are low. There is also the question as to whether there is a role for such research in India or whether we should stick to research on how to adapt and apply conventional oral examination techniques.
Steps should be taken to implement oral cancer screening as a health care programme integrated into the present, or to-be-improved, health care system, utilizing conventional oral examination as the tool in high-risk individuals. Infrastructure and government support are essential for its adoption. Research should progress on the development of newer, affordable, “made in India” gadgets with better sensitivity and specificity in a community setting.
The author is Professor, Department of Head and Neck Surgery and Oncology, Amrita Institute of Medical Sciences, Kochi.