Cancer screening programs: cost and effect questions
In any cancer-screening program it is important to define the population that is to be screened. The population that is defined as having the highest rate of the particular cancer is obviously the most cost effective to scrutinize with the highest number of patients identifies per 1,000 screened. Moreover, the efficiency of the screening will depend on the stringency of the defined risk factors, i.e. the more stringently risk factors are defined; the greater will be the pick-up-rate per 1,000. However, when screening is limited high risk patients, individuals who fall outside these strictly defined risk parameters are not eligible for screening and will therefore be missed.The addition of HPV as a risk factor for oral cancer has made it difficult if not impossible to easily define high risk individuals. OPPORTUNISTIC mass screening is the only viable choice to find oral cancer at precancerous or very early stage high survival stages.
Many professional associations and societies have developed cancer-screening guidelines. Accordingly, in spite of differing views, there has evolved agreements on screening guidelines for colorectal, breast, and cervical cancers (1). However, specific guiding principles have yet to be developed for a number of other cancers, especially for populations that lack any persuasive evidence to indicate that a likelihood of high risk exists. This is particularly true for oral cancers particularly in individuals below the age of 40 who are non-smokers and/or non-consumers of alcohol. In part, this has been caused by the recognition that oral cancer is relatively infrequent accounting for only ~ 3 percent of cancers in men and 2 percent cancers in women in the United States.
Oral cancer screening: defining the problem
Oral cancer is an ideal cancer to identify early by screening. It is frequently preceded by an identifiable pre-malignant lesion and the progression from dysplasia occurs over a period of 2,5-8 years. However, published series (2) show that the majority of oral cancers present at an advanced stage (III and IV), when cure rates abysmal. This may be due to the stereotypical oral cancer patient (an elderly male, who abuses tobacco and alcohol) not presenting to health care professionals. Nonetheless, late diagnosis may be related to the fact that an increasing number of oral cancer patients who do not fall into the “high risk” group are not recognized by health care practitioners as being at risk of developing oral cancer. This concept is exemplified by the rise of the female population that is affected by oral cancer. In the 1930’s the male to female ratio for oral cancer was 10:1. With increases in tobacco and alcohol use by women that ratio 2:1 and in our series at the University of Maryland the ratio is 3:2 (unpublished). If screening for oral cancer were restricted to males almost 40% of the cases would be overlooked today, as opposed to only less than 10% of non-diagnosed cases in the 1930’Mw. Interestingly, in this regard there are gender differences between women and men relating to smoking and oral cancer. The relative risk is much higher in women at all levels of smoking (3). Moreover it has also been suggested that women may be more susceptible to cancers that are provoked by alcohol (4).
The two most common approaches of detecting oral cancers are visual inspection and cytology. Neither of these modalities has been shown decrease mortality (5). Consequently, both the United States Preventive Services Task Force (USPSTF) and Canadian Task Force on Preventive Health Care (CTFPHC) have taken a position that although screening can lead to early detection, there is insufficient evidence to recommend for or against routine screening for oral cancer (6, 7). However, both organizations support the principle that educational programs directed toward reducing the use of tobacco and alcohol have merit in sustaining a healthier life. Also the USPSTF recommends a regular dental examination in patients at high risk of oral cancer (7) and the CTFPHC suggests annual examinations by physicians or a dentist to examine for oral cancer in patients older than 60 years with risk factors such as smoking and heavy drinking (6). Based on the fact that the primary risk factors intra-oral (excluding lips) cancer in American men and women is the use of tobacco and alcohol, albeit that infection with HPV-16 and HPV-18 virus has been associated with greater risk of developing squamous cell carcinoma of the oropharynx (8). Despite these recommendations, the National Center for Health Statistics Supplement Survey reported in 1992 that only 14% of the U.S. population has ever had an oral cancer screening (9).
Incidence of oral cancer in young patients: a changing trend
As a result of non collecting population data from screening large populations for oral cancers, little or no attention was initially given to the development of changes in patterns of disease susceptibility. This was especially true for an emergent group of young patients that develop oral cancers, particularly those involving the tongue. Consequently, the increased incidence of tongue cancer was first highlighted by testimonials, letters to the editor, and case reports from Oral Maxill