The Maxillofacial Center for Diagnostics & Research

Abstract

Smokeless tobacco (ST) use is an accepted risk factor for oral cancer in the US, but the major proof of this is based largely on a single epidemiologic (case-control) comparison of women, while the chewing of tobacco is predominantly a habit of men. Objective: The present investigation sought to compare gender-specific oral cancer mortality and incidence rates in West Virginia (WV), the state with the highest per capita consumption of ST, with rates from other states and with the US average rates. It was hypothesized that the cancer rates for West Virginia males would be significantly greater than the US average or than states with less ST consumption. Study design: 1993-1995 data from the WV Cancer Registry were compared to data from contemporary SEER incidence rates for the US and to mortality rates from CDC's National Center for Health Statistics. Results: The average annual incidence rates for oral/pharyngeal cancer in WV males and females were 13.4/100,000 and 5.1/100,000, respectively, compared to US rates of 15.4 and 5.7. The average annual mortality rates for this disease in WV males and females were 4.2 and 1.6, respectively, compared to 4.4 and 1.5 for the US. WV oral/pharyngeal mortality rates for both genders were statistically significantly lower than US rates throughout 1950-1980. Of other potential oral cancer etiologic factors, a very low prevalence of alcohol abuse in West Virginia seemed to be relevant. Conclusions: The hypothesis was not confirmed by data analysis. West Virginia is the state with the highest per capita consumption of smokeless tobacco and yet has less oral/pharyngeal cancer than the US average. The authors strongly urge additional and improved epidemiologic evaluation of the oral cancer risk of smokeless tobacco use in US males.

Introduction

Tobacco chewing has been accepted as an important risk factor for oral carcinoma in the United States since a federally commissioned expert panel came to that conclusion in 1986.1 Certain health care professionals have espoused this view since the early part of the century.2,3 The etiologic association appears to be based on several important and well-known facts. Firstly, tobacco is a well established carcinogen for mucosal surfaces, including the mouth.4,5 Secondly, oral cancers in smokeless tobacco users in Western cultures arise most frequently at the site of chronic tobacco placement.6,7 Thirdly, Winn et al8-11 have clearly demonstrated an increased risk of oral carcinoma among older white females who have dipped snuff most of their lives.

The white mucosal lesion called smokeless tobacco keratosis, previously known as leukoplakia or tobacco pouch and quite common in smokeless tobacco users, is now accepted as a precancer, albeit somewhat different from true leukoplakia, probably having a lower risk of cancer development than the smoking-related leukoplakias.12-14 Additional detrimental oral effects of the use of smokeless or spit tobacco have also been established.11,14-19

Much has also been made of the high relative frequency of oral cancer on the Indian subcontinent, where long-term, high-volume smokeless tobacco use is endemic. Some hospital-based reports from India, in fact, have indicated that oral cancer represents more than half of all diagnosed carcinomas.2,3,12,15 These rates are, however, deceptive and subject to the same biases of all hospital-based frequency data. Incidence rates of oral cancer in India are, indeed, high, approximately twice those of the United States.12,20 But certain regions of Brazil, France, Canada, Australia and other Western countries have even higher rates.

Oral cancer in India is also influenced by the popular habit of tobacco (bidi) smoking, but the relative risk of betel/tobacco quid chewing has been shown to be at least twice as great as the risk of bidi smoking.20 The combination of the two habits increases the risk even more. Approximately 30% of oral cancers in India are attributed to betel/tobacco chewing alone and an additional 50% to the combined habits of chewing and smoking.15

Certain Western clinicopathologic investigations of the relationship between smokeless tobacco use and oral cancer have demonstrated an equivocal association. Rosenfeld and Calloway21 found that 78 of 394 (20%) oral cancer patients from the Southeastern U.S. were snuff users, but no mention was made of the prevalence of the habit amongst the local population. This may be a serious oversight. For example, Sundstrum et al7 found that 41 of 375 (11%) Swedish males with oral cancer were users of smokeless tobacco, but contemporary surveys indicate that 20-25% of Swedish men were at that time using snuff daily.22

Moreover, several investigations which have looked at biopsied samples of smokeless tobacco keratosis have found very little substantial epithelial dysplasia or malignancy.6,7,23-27 Of 114 biopsies taken from clinically "severe" lesions in 1,200 Swedish snuff dippers, Axell et al6 found no dysplasias or carcinomas whatsoever. Smith23 had a similar experience with 157 "severe" keratotic lesions in U.S. snuff users, as did Daniels et al26 with 138 biopsy samples from keratic lesions in professional baseball players. Even the studies which found dysplasia could find none that were more than slightly dysplastic, and no correlation could be found with habit intensity or duration.24,25

Other reasons exist for wondering about the strength of this association:

• there seems to be no increase in the prevalence of oral cancer among U.S. baseball players, frequent users of snuff and chewing tobacco19,27
• malignant transformation of smokeless tobacco keratosis seems to be a rare event6,7,28
•  
• very few oral cancers have been produced in laboratory animals by the exclusive use of smokeless tobacco (i.e., without the use of extreme concentrations or added etiologic factors)5,29,30

The cancer risk, in fact, is considered by Rodu et al31,32 to be so much less than the risk from smoked tobacco that they suggest switching inveterate smokers to a chewing habit as a means of substantially reducing their overall risk of disease.

Spit tobacco use among U.S. white males has enjoyed a recent resurgence of popularity,11,33-36 and there are some who expect an oral cancer epidemic to occur as these young men reach their 60s and 70s.11,37 Because of this it is important to more firmly establish a causal relationship between the habit and the cancer. The excellent case-control investigations of Winn et al.8-11 have assessed the risk in U.S. women, but others assessing the risk in men have either shown no correlation or based their conclusions on only a handful of snuff users.38-41

Additional or corroborative studies are sorely needed, especially studies pertaining to male users and especially in light of the current controversy surrounding the suggested smoking cessation strategy of switching to smokeless tobacco.42-44 It seems apropos to evaluate oral cancer frequency in a U.S. population with a very high use of smokeless tobacco products among its male members. The purpose of the present investigation, therefore, was to compare oral/pharyngeal cancer mortality and incidence rates in West Virginia, the state which traditionally has had the highest per capita consumption of smokeless tobacco,17,35,45 with other states and with the national average rates for this disease.

Our hypothesis, based on the accepted relative risk of developing oral cancer from the chronic use of smokeless tobacco, was that the oral/pharyngeal cancer incidence rate for males would be significantly greater than the U.S. average and also greater than rates for other state populations with less smokeless tobacco consumption.

Materials and Methods

The West Virginia Department of Health and Human Resources, Bureau for Public Health, implemented a statewide cancer registry in 1992 which included cancer diagnoses of all anatomical sites, excepting basal cell and squamous cell carcinomas of the skin, and including in situ cases.46-48 Data for the West Virginia Cancer Registry (WVCR) was collected from all hospitals (n=61) within the state as well as the eight free-standing pathology laboratories and two freestanding radiation treatment centers in the state. Facilities without tumor registries provide access to medical records of cancer cases for the WVCR abstractors.

To identify cases of cancer in residents who traveled outside West Virginia for diagnosis and treatment, the WVCR has reciprocal data exchange with the central registries of Pennsylvania, Maryland, the District of Columbia, Virginia, Ohio, Kentucky, North Carolina, Florida, Arkansas, and Mississippi. To identify cases not found by routine case-finding activities, all West Virginia residents who died in 1993-1995 with cancer listed as an underlying cause of death were matched against the WVCR data. Those cases which were verified to be reportable based on year of diagnosis were included in the WVCR.

The data in the present paper are a summary of data collected and reported by the WVCR as well as raw data provided to the authors by the West Virginia Office of Epidemiology and Health Promotion.46-48 The WVCR rates were variously compared to those from the 1990-94 or the 1994 SEER (Surveillance, Epidemiology, End-Results) age-adjusted incidence rates for the U.S.49,50 Mortality rates were taken from the public use tape provided by CDC's National Center for Health Statistics. All state and national rates are listed per 100,000 population and are age-adjusted to the 1970 U.S. standard population. For purposes of this paper, the terms oral and mouth include the vermilion border of the lips (ICD-951 codes 140.1-140.5, 141, 143-145) and the terms pharynx and pharyngeal include the nasopharynx, oropharynx and hypopharynx (ICD-9 codes 146-149).

For all practical purposes state data can be assumed to pertain to whites only, as the proportion of nonwhites in the 1993-1995 West Virginia population was only 4%. In 1993 the estimated state population was 1,820,137 (876,311 males; 943,826 females).46,48,52 West Virginia is the only state situated entirely within Appalachia and one of only two states defined by the U.S. Bureau of the Census as being "predominantly rural."46 The state has the second oldest population in America.

The use of smokeless tobacco appears anecdotally to have been popular for generations among its citizens, men and women both, but its seems no longer popular among the women. Data from earlier years are, unfortunately, not available, but informal surveys conducted by one of the present authors (JEB) in the mid-1970s found that 40-50% of selected male students attending West Virginia University used smokeless tobacco daily.

The habit is certainly endemic today among the state's male population, as illustrated in Table 1. Usage rates provided in this table have been deliberately taken from the mid-1980s in order to minimize the effect of the current popularity, which began to surge in the late 1970s. Figure 1 shows a biphasic pattern of popularity in the late 1980s, with the youngest and oldest men most prone to using chewing tobacco and snuff. At least16% of the group most susceptible to smokeless tobacco-related oral carcinoma, males older than 65 years of age, were users of these products at that time.

Results

Mortality rates. Cancer was the second leading cause of death in the state population, with more than 4,700 residents dying from cancer during each year of observation, 1993-1995. The age-adjusted average annual mortality rate for men was 236/100,000; for women it was 150/100,000. This was significantly higher (p=0.0002) than overall U.S. rates for males and also higher than the U.S. rates for females (Table 2).

When cancers of the lungs and bronchial tree were excluded, however, the state's cancer mortality rate for men was close to parity with the average rate for U.S. males. No anatomic sites other than the lower respiratory system and the prostate were significantly different from the total U.S. experience. Non-neoplastic lung diseases also contributed significantly to the overall mortality rate for men, who experienced some of the country's highest death rates for chronic obstructive pulmonary disease, pneumonia and influenza.47

The overall cancer mortality rate for West Virginia ranked the state 12th and 10th, respectively, for males and females among the 50 U.S. states. The rank for males, however, dropped to 26 when lung cancers were excluded from the calculations. The state ranked fourth among the states in deaths related to smoking; 25% of its adults were smokers.35,45

Cancer deaths from oral/pharyngeal lesions represented 2.0% of all male cancer deaths and 1.2% of all female cancer deaths in West Virginia. Gender differences were noted in mortality rates. Oral/pharyngeal cancer death rates for state males and females were 4.2/100,000 and 1.6/100,000, respectively. These rates were comparable to the average rates for U.S. males and females: 4.4 and 1.5, respectively. National mortality rates for an earlier time period, 1950-1980, show that males throughout Appalachia, and most of rural America, had statistically significant lower rates for this cancer during the entire three decades (Figure 2).53,54 This was also true for West Virginia males. Overall, the state population ranked 26th for males and 30th for females among the U.S. states relative to oral/pharyngeal cancer mortality.

Annual mortality rates of relatively uncommon events in small populations may show considerable variation from year to year, and so this was specifically reviewed for the years 1991-1995. The West Virginia oral/pharyngeal cancer mortality rates decreased by 1.4 between these years: 3.8, 3.5, 3.1, 2.5, and 2.4, respectively. This compares to a decrease of 0.3 for the much larger population cohort of the U.S. SEER investigation for 1990-1994: 3.0, 2.9, 2.8, 2.8, and 2.7, respectively.50

Figure 3 demonstrates that, as expected, West Virginia deaths from oral/pharyngeal cancer increased in frequency with increasing age. Comparison with national oral/pharyngeal cancer rates showed the state rates for females to be less than or similar to the national rates at all ages of life, but the rate for males 55-64 years of age was approximately 30% higher than the national rate for males of a similar age group. This was the only age and gender cohort in which oral/pharyngeal cancer was among the most common five cancers diagnosed in state citizens.

Table 3 provides a state-by-state comparison of estimated frequencies of smokeless tobacco use among males with each state's annual oral/pharyngeal cancer mortality rates for males. There seems to be no correlation between these two parameters and, in fact, the area with the least smokeless tobacco use, the District of Columbia, had the highest oral/pharyngeal cancer mortality. Likewise, all but one of the ten states with the lowest user rates had mortality rates higher than West Virginia. County-by-county comparison of smokeless tobacco use in West Virginia with oral/pharyngeal cancer mortality rates likewise showed no pattern of association: more than half (53%) of counties with use rates below the state average had oral/pharyngeal cancer rates above the state average.55

Incidence rates. More than 8,400 cases of cancer were annually diagnosed in state residents during 1993-1995, providing average annual incidence rates of 429/100,000 males and 320/100,000 females. This compared to 472 for U.S. males and 342 for U.S. females in 1994 (Table 4).50 The most commonly diagnosed primary cancer among West Virginia males was prostate, followed by lung/bronchus and colon cancers. For West Virginia women, the most commonly diagnosed primary cancer was cancer of the breast, followed by lung/bronchus and colon cancers.

The average annual age-specific oral/pharyngeal cancer incidence rate for the state was 8.8/100,000 population, compared to 10.7/100,000 for the total U.S. population.48,50 The average rate for males was 13.4, substantially below the national rate for males (15.4). Likewise, the state's female rate of 5.1 was somewhat less than the national female rate of 5.7. West Virginia annual incidence rates varied by 0.9 points between1993 (9.3), 1994 (8.4) and 1995 (8.7). For comparison, the SEER rates for 1990-1994 were 11.1, 10.8, 10.5, 10.8, and 10.2, respectively, showing a similar 0.9 point variance.

Data from the adjacent state of Kentucky, with a more established cancer registry, also demonstrated a lower oral/pharyngeal cancer incidence in the eastern portion of the state , i.e. within tobacco-chewing Appalachia, than in the more populous western part of the state.56

As with mortality rates, the incidence of oral/pharyngeal cancer in the West Virginia population increased with age. Incidence at all age levels was less than that of the national population as a whole (Figure 4). Most cases (87%) were found in patients 50 or more years of age.

In order to determine whether or not the WVCR was identifying an acceptable level of cases, incidence was specifically determined for two rare oral cancers, verrucous carcinoma, the so-called "snuff dipper's cancer," and carcinoma in situ, considered by some to be a precancer rather than a true cancer. The average annual incidence rate for verrucous carcinoma was only 0.3/100,000 population, with equal rates for the two genders. This was similar to the rate of 0.1/100,000 determined for another U.S. population.57 Carcinoma in situ had an average annual incidence of only 0.2/100,000 population, which was quite similar to the rates determined for other populations.58,59 From this perspective, then, it appeared that an acceptable level of case ascertainment was reached by the WVCR.

Histopathology. The West Virginia oral/pharyngeal malignancies were usually squamous cell carcinomas (85%), with a small proportion being salivary adenocarcinomas (6%), lymphomas (5%) and verrucous carcinomas (3%), among others. Noninvasive carcinomas in situ represented 1.5% of all diagnosed malignancies of the oral cavity and pharynx.

Stage at diagnosis. Among West Virginia residents diagnosed with oral or pharyngeal cancer during 1993-1995, 42% had localized lesions without metastatic spread to regional nodes or to distant sites. An additional 44% had metastatic spread to at least one cervical lymph node at the time of diagnosis. This was similar to the total U.S. experience (Table 5). The proportion of West Virginia cases without staging information was considerably less than that of the SEER investigation.

Oral and pharyngeal cancers in West Virginia females were much more likely to be localized at diagnosis than those in males (52% vs. 38%, respectively). Distant metastases were likewise less common in females than in males (4% vs. 7%, respectively). Age was also something of a factor in this regard, with persons 25-44 years of age having a greater proportion of localized disease than those who were 45-64 years of age (46% vs. 35%, respectively).

Discussion

Our hypothesis that the male population of West Virginia would demonstrate considerably elevated oral/pharyngeal cancer incidence and mortality rates when compared to the rest of the U.S. population was not confirmed by our data analysis. West Virginia is the state with the highest per capita consumption of smokeless tobacco products, with at least 16% of its older men claiming daily use, yet the state has oral/pharyngeal cancer rates equal to or lower than the U.S. average and lower than many other states with no significant smokeless tobacco use in their populations. Nor is there an apparent epidemic of oral cancer in this population, despite the fact that its older male users had, presumably, lifelong habits.

The present study design, however, does not allow us to make a strong statement about causality. Our investigation lacks specific exposure information about those who did and did not develop oral/pharyngeal malignancy. Nevertheless, comparison of mortality and incidence rates between different populations is a time-honored and still accepted research technique, despite the lack of specific exposure information in the various populations.50,53,54,60

Additional flaws in our study design include the relatively small population base, the use of data from a new cancer registry which may not have identified all oral and pharyngeal cancers occurring in the population, and the inclusion of cancers from the vermilion border, the major salivary glands and the nasopharynx, all of which are biologically different from intra-oral carcinomas.12 Under-reporting from embryonic tumor registries has been documented by the well-established cancer registry of New York state, which determined that it had missed approximately 12% of appropriate cases during its earliest years of existence.61 Case ascertainment in the WV data, however, seems to be acceptable, even though doubtlessly imperfect. The WVCR was able to identify, for example, cases of rare types of oral/pharyngeal cancers, such as verrucous carcinoma and carcinoma in situ, at levels similar to those of other studies from long-established registries, and mortality rates have remained consistently below the national average since at least 1950.[50,53,54,56-58]

Rather than rejecting the WV results out of hand, we feel that it would be more appropriate to accept inherent flaws and use the present investigative results to encourage less flawed and more sophisticated research into the association between smokeless tobacco use and oral cancer. The ongoing search for cancer etiologies is filled with impaired data and has become, in some opinions, a miasma of plausible, implausible and often untenable associations and theories.[62,63] A survey of the published investigations into the smokeless tobacco-cancer link shows this topic to be no exception, and a review of the epidemiologic evidence is in order.

Winn et al[10] in their well-accepted case-control investigation found in 1981 that 46% of 255 older North Carolina women with oral/pharyngeal cancer were long-term users of snuff, compared to 30% of 410 interviewed controls. Statistical analysis led these authors to conclude that one-third of the oral/pharyngeal cancers in their female population were attributable to the use of snuff, and they estimated an elevated risk of approximately four-fold, with higher risk for anatomic sites in close contact with the snuff.

A 1988 investigation by Blot et al[10] touched only lightly on the association between smokeless tobacco use and oral/pharyngeal cancer in a report dealing primarily with the effects of smoking and alcohol abuse on the development of this disease. These authors could make no conclusions relative to males because nearly all male smokeless tobacco users were also tobacco smokers, but they could state that there was "a significant excess of oral cancer which was detected among nonsmoking women who used snuff."

Spitz et al[38] based their positive correlation on a very small number of snuff users (n=9) among a relatively small group of oral/pharyngeal cancer patients (n=110) . All of the snuff users also drank alcohol and smoked cigarettes or cigars, hence, confounding variables could not be ruled out as responsible for the association. Because of the difficulty controlling for various tobacco habits, the authors concluded that there was only marginal statistical significance to the effect of smokeless tobacco use.

Stockwell and Lyman[39] found a rather strong association between smokeless tobacco use and oral/pharyngeal cancer in a 1986 study of Florida citizens but, again, their conclusion was based on only eight smokeless tobacco users among 1,277 persons with oral/pharyngeal cancer (excluding those with salivary and nasopharyngeal disease). These authors specifically found a statistically significant link between smokeless tobacco use and cancer of the gingiva and buccal mucosa, popular sites of smokeless tobacco placement, but they could not verify a high accuracy of tobacco use data among their control group, which consisted of patients with cancers from other anatomic sites. The present authors feel that their established elevated risk must be tempered by the small number of identified users, the flawed tobacco-use data, and the paradoxical fact that tumors of sites not usually linked to smokeless tobacco use, the salivary glands and nasopharynx, were among the sites with the greatest risk (determined from only three snuff users among 110 persons with cancers of those two sites).

More recent epidemiologic analyses of the relationship between smokeless tobacco and cancer are perhaps the most telling, since they found absolutely no association with oral and pharyngeal cancers in U.S. and Swedish populations. The 1992 U.S. investigation by Sterling et al[40] combined a national stratified probability sample of death certificates and a nationwide health interview survey, with great attention to confounding variables, to conclude that the relative risk for those who use smokeless tobacco was 1.00 for males and 1.04 for females.

And finally, the 1998 population-based Swedish study by Lewin et al41 found a strong and synergistic correlation between smoked tobacco, alcohol abuse and oral cancer, but concluded that there was no elevated risk from the chronic use of smokeless tobacco.

Our own data refer predominantly to male users, some who use snuff, some who use chewing tobacco, some who smoke, and some who use no tobacco products. Our study approaches the issue from a completely different epidemiological perspective and lacks, as mentioned, specific exposure information relative to individuals studied. Confounding variables cannot, therefore, be controlled and biological plausibility cannot be firmly addressed, but the combination of past and present epidemiologic investigations must certainly call into question the strength of the association between the smokeless tobacco habit and oral cancer.

The data also suggest questions not previously addressed for Western populations. Could snuff dipping be of greater etiologic importance to females than to males? Is it possible that not only gender differences, but the actual methods of spit tobacco use have influenced the development or lack of development of oral cancer in West Virginia citizens? The daily consumption of smokeless tobacco, the amount of time each quid is kept in place, the type of tobacco habit, the type of smokeless product used, the age of habit onset, and other factors have been shown to be germane to the development of oral cancer and precancer in India,12,15,20 and to a lesser extent in Western populations,6,13,16-18 but none of these are addressed in the present study.

Additionally, could other environmental or dietary mechanisms be protecting the residents of West Virginia from oral/pharyngeal cancer? Recent life-style evaluations clearly demonstrate a rather poor overall health for the citizens of West Virginia, but the population does have a normal life expectancy and has one of the oldest average ages in America. It also has one of the lowest alcohol abuse rates in the nation (ranks 48th among the states).64 The investigation by Blot et al10 reiterated the long-established cocarcinogenic effect of heavy alcohol use in association with oral cancers and also stressed that alcohol is a carcinogen in and of itself, not necessarily requiring a co-factor to produce malignancy. This is has been confirmed repeatedly by others.65 Could this synergistic effect be even stronger than previous research has indicated? It is possible, if not likely, that the low consumption of alcoholic beverages is helping to keep down the incidence rates in West Virginia.

There still appear to be more questions than answers relative to the carcinogenic effects of smokeless tobacco. It is likely that the present report will add to the confusion. Clearly, additional and more powerful epidemiologic research is needed in this arena. At the very least, the case-control study by Winn et al8 should be duplicated in a male population, which is after all the gender most likely to participate in this habit in the United States.

The authors do not contend that the spit tobacco habit is not a premalignant condition or that smokeless tobacco keratoses are not premalignant lesions, but the cancer risk of this habit as practiced by Western populations appears to be considerably less than the risk from other similar habits and lesions, such as tobacco smoking and leukoplakia. This paper should not be construed as an endorsement of the use of smokeless tobacco or tobacco in any form. The reader is also reminded that the risk of other diseases, such as periodontal destruction and cardiovascular disorders, from this habit is significant.

Conclusions

A state with a presumed long-standing history of popular and culturally accepted smokeless tobacco use has, unexpectedly, oral/pharyngeal cancer incidence rates similar to or lower than the average for the U.S. Mortality rates have also been lower than the national average since at least 1950. This is also the case for other Appalachian states. The data suggest that the oral cancer risk from this habit may be less than previously suspected and that there may be no "oral cancer epidemic" as today's young users reach old age, but strong conclusions cannot be reached because of the crude nature of the investigative design and because of a lack of specific exposure information.

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Tables:

Table 1: Smokeless tobacco use among youth, grades 9-12, and among adults, aged 18 and older, 1992-1993.35 For adults the data refer to current use; for youth the data refer to use during the past month.

Table 2: Comparison of average annual age-adjusted invasive cancer mortality rates for selected anatomic sites for West Virginia (1993-95) and the U.S. (SEER data, 1990-1994), ranked according to WV male rates, all races combined.48 Rates are provided per 100,000 persons; all rates are age-adjusted to the 1970 U.S. population and exclude in situ cases.

Table 3. Smokeless and smoked tobacco use rates for U.S. males older than 18 years of age (1993 data),35 compared with annual age-adjusted oral/pharyngeal cancer mortality rates, by state (1990-1994 data).50 Ranked by proportion (%) of adult males currently using smokeless tobacco.

Table 4: Comparison of average annual age-adjusted invasive cancer incidence rates for selected anatomic sites for West Virginia (1993-95) and the U.S. (SEER data, 1994), all races combined, listed according to the ranking of Table 2.48,50 Rates are provided per 100,000 persons; all rates are age-adjusted to the 1970 U.S. population and exclude basal and squamous cell skin cancers and in situ carcinomas.

Table 5. Cancer of the oral cavity and pharynx in whites. Stage of disease at diagnosis, West Virginia residents (1993-1995) compared with U.S. averages (1986-1993).48,50,58

Table 1: Smokeless tobacco use among youth, grades 9-12, and among adults, aged 18 and older, 1992-1993.³⁴ For adults the data refer to current use; for youth the data refer to use during the past month.

Table 2: Comparison of average annual age-adjusted invasive cancer mortality rates for selected anatomic sites for West Virginia (1993-95) and the U.S. (SEER data, 1990-1994), ranked according to WV male rates, all races combined.⁴⁷ Rates are provided per 100,000 persons; all rates are age-adjusted to the 1970 U.S. population and exclude in situ cases.

Note: difference between West Virginia and total U.S. rate is statistically significant (p<=0.0002) for lung/bronchial tree (both genders), prostate (males) and total sites (males).

* n/a = not applicable

Table 3. Smokeless and smoked tobacco use rates for U.S. males older than 18 years of age (1993 data),³⁴ compared with annual age-adjusted oral/pharyngeal cancer mortality rates, by state (1990-1994 data).⁴⁹ Ranked by proportion (%) of adult males currently using smokeless tobacco.

* current use = has used it within the past 30 days

Table 4: Comparison of average annual age-adjusted invasive cancer incidence rates for selected anatomic sites for West Virginia (1993-95) and the U.S. (SEER data, 1994), all races combined, listed according to the ranking of Table 2.^47,49 Rates are provided per 100,000 persons; all rates are age-adjusted to the 1970 U.S. population and exclude basal and squamous cell skin cancers and in situ carcinomas.

* n/a = not applicable

Table 5. Cancer of the oral cavity and pharynx in whites. Stage of disease at diagnosis, West Virginia residents (1993-1995) compared with U.S. averages (1986-1993).^47,49,57

* rounded to the nearest integer

** total excludes in situ data

Legends for Figures

Figure 1: Age-specific rates for smokeless tobacco use in West Virginia, presented as the proportion of current users, by gender.45

Figure 2: Comparison of average annual oral cancer mortality rates between state economic areas, 1970-1980, white males only.53 The U.S. average at the time was 4.3/100,000 white males per year.

Figure 3: Age-specific average annual oral/pharyngeal cancer mortality rates for West Virginia, 1993-95 compared with U.S. rates for 1990-1994.48,50 Rates are given as the number of newly diagnosed cases per 100,000 population per year, by gender.

Figure 4: Age-specific average annual oral/pharyngeal cancer incidence rates for West Virginia, 1993-95 compared with U.S. rates for 1990-1994.48,50 Rates are given as the number of newly diagnosed cases per 100,000 population per year, by gender.