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 Maxillofacial and Head and Neck healthcare professionals. Later, the fact that head and neck cancer, particularly tongue cancer was escalating in young adults in North America, and internationally, began to be recognized from retrospective studies preformed in the late 1980’s (10-16) For example, a review of mortality trends in Europe for a 34-year period from 1955 revealed that a number of countries in Central and Eastern Europe had a 2-fold increase in oral cancer. This increase principally involved males that were under 45 years of age. Similar increases were observed in women in a number of countries (14). In the United States, similar studies preformed during a 20 year period began in the 1960’s revealed that there was a near four-fold increase of oral cancer in males ages 30-39 in the State of Connecticut (16). Likewise, DePue (13) noted earlier that there was an increase in the mortality rates of adults younger than 30 and indicated that these data suggested that this trend began in the mid 1970’s.
Most recently, Schantz and Yu (17) examined the cancer surveillance database from the National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) Program. These investigators calculated age-adjusted incidence rates for head and neck cancers using a join point regression model, and described tongue cancer incidence trends and established the statistical significance of temporal changes for this disease. These studies revealed that from 1973 to 1997, there were 63,409 head and neck cancer patients in 9 SEER registries. Among this group of patients, 3339 individuals or 5.2%, were noted to be younger than 40 years of age. While the incidence of head and neck cancer remained stable in patients older than 40 years between 1973-1984 compared to the period 1985-1997, tongue cancers in adults younger than 40 years increased almost 60% during the same intervals of time. Notable, was that the estimated annual percentage change occurred until 1985, after which the incidence rate stopped rising but remained increasingly high. In an attempt to define the change more precisely it was discovered that the change in tongue cancer incidence rates f