Introduction

The school years represent a time span of tremendous growth and development for children. These early years are an important formative stage for health behaviors. Children are constantly ex-posed to new situations, ideas, and concepts, and the habits they develop during this period have a lifelong influence on their health. Given that youngsters are malleable and face extreme contemporary pressures, it is not surprising that the leading causes of death for school children are linked to high-risk behaviors. Kann et al¹ noted that 72% of all deaths among school-age individuals are the result of four causes: motor-vehicle accidents, homicides, suicides, and other unintentional injuries. Some of the major risk factors for youth morbidity (eg, alcohol use and early sexual experience) also reflect behavioral patterns that increase risks for future chronic diseases, including cancer. Furthermore, despite significant progress in recent years in education on cancer prevention and control issues, the American Cancer Society predicts that in the United States, men have a 1 in 2 lifetime risk of developing cancer, and the risk for women is 1 in 3.²

The general health of school- aged adolescents is somewhat of a paradox; childhood is both a healthful stage of life and a period of extreme risk. It is seldom considered a time appropriate for serious, preventive interventions. Remarkably, the health systems of the United States generally are designed for treatment and care of pediatric or adult health problems. Lipsitz³ characterizes the chasm children face in health care as a lack of "emphasis on the years between the starting and the finishing lines." Behaviors associated with principal cancer risk factors are also initiated during school- aged years, with adolescence in particular standing out as a time of extreme vulnerability.⁴ For example, D'Onofrio⁵ noted that children almost never enter school as smokers and that very few begin to smoke after they leave school. Not surprisingly, the same can be said for most health risk behaviors. These behaviors "are usually established during adolescence, are interrelated, persist into adulthood, contribute simultaneously to poor health, education, and social outcomes, and are preventable."⁶ Estimates place the percentage of preventable cancers arising from youth-initiated behaviors at 60%.⁷

Purpose of the Study

The purpose of this study was to examine the prevalence of cancer risk behaviors, including tobacco use, irresponsible sexual activity, dietary patterns, and physical activity, in a national sample of youth. Behavioral differences by sex and racial/ethnic groups were examined to determine significant patterns where such information may be valuable. This information may not only assist health educators as they develop prevention programs, but also increase the awareness of clinicians as they work with adolescents in medical settings.

Methods

Subjects

Data were collected in February through May of 1993. Subjects consisted of 16,296 students enrolled in grades 9 through 12 across the United States. Data collectors from the Centers for Disease Control and Prevention (CDC) used a three-stage cluster sample methodology in which schools were randomly selected from previously selected sampling areas, and intact classes within schools were invited to participate in the study. Efforts were made to oversample in schools with high populations of blacks and Hispanics to achieve adequate representation. Additionally, 24 state and nine local surveys were performed, with either all schools in an area or intact classes within schools selected for participation. For the national sample, records of subjects were weighted to account for nonresponses. The data are considered representative of students in grades 9 through 12 in public and private schools nationally.¹

Not all state and local data were weighted. The school response rate was 78% and, when combined with a student response rate of 90%, yielded an overall response rate of 70%. Usable surveys numbered 16,296 and were returned and coded by CDC staff. Due to small numbers of Asians/Pacific Islanders, Native Americans, and Alaskan Natives, data from these groups were removed from further examination in this study. The 1993 data are the most recent available for analysis, although the 1995 data should be available by mid-1997. Preliminary examination of 1995 data reveals little change from the data presented herein.

Instruments

The Youth Risk Behavior Survey (YRBS), an 87-item survey designed to examine specific health-risky be-haviors of adolescents, has been in use since 1991.⁸ Factors used for this study were those estimated by Doll and Peto⁷ to contribute most to cancer deaths, including tobacco use, sexual behavior, diet, and related physical inactivity. Subsequently, cancer-specific risk behavior items were isolated from the total survey, including ten items related to tobacco use, nine related to sexual activity, seven related to dietary patterns, and eight related to activity and exercise patterns. A complete discussion of the psychometric properties of the YRBS has been presented by Brener et al.⁸

The instrument has been demonstrated to possess acceptable reliability.⁸ In examining the reliability of the YRBS instrument, investigators found that Kappa statistics for 90% of the items equaled or exceeded 41, which is considered moderate or better. Reliability estimates were similar for both sex and grade level. All but two of the items used in the analysis of cancer risk behaviors had levels of 70% or higher, revealing substantial reliability in the data.

Analysis

Simple frequency rates were initially generated. Group differences (sex and race) were then examined using Kruskal-Wallis one-way analyses of variance.⁹ Post-hoc analyses of significant results were conducted with multiple Mann-Whitney U tests using Bonferroni protection to maintain the overall alpha level at .05.⁹ Data were analyzed using the Statistical Package for the Social Sciences.¹⁰ Because of the large sample size, Kruskal-Wallis and Mann-Whitney coefficients are so large that only significance levels are reported. (Actual values are available from the authors.)

Results

Analyses were conducted on a usable sample of 14,997 subjects. Ages of the respondents ranged from 13 years or younger (0.1%) to 18 years or older (17.2%), with a median age of 17 years. Males comprised 49% of the sample, and 51% were female. Ninth through 12th grades were sampled almost equally, with 3,500 to 4,000 students samples from each grade level. The racial composition of the sample used in this study was 44.1% white, 24.5% black, and 31.3% Hispanic (of all origins).

Tobacco Use

Over two thirds (69.5%) of the students surveyed had tried cig-arettes at least once. Significantly more males (70.1%) than females (68.7%) had tried tobacco at least once during their lives (P<.01), and males also were more likely to have tried tobacco at a younger age than females (P<.01). Slightly more males (24.9%) than females (24.5%) had smoked cigarettes regularly as well and were heavy smokers (P<.01). Hispanics had the highest levels of experimentation with cigarettes (71.8%), followed by whites (70.3%) and blacks (67.1%). All groups were significantly different (P<.01). Nearly equal numbers of white and black males and females had tried tobacco at least once, but significantly more Hispanic males (75.1%) had tried tobacco than Hispanic females (68.1%) (P<.01).

One quarter of the students sampled had smoked at least one cigarette a day for at least a month at some time. Only 13.8% of the students, however, had smoked for 20 or more days during the period prior to sampling. Significantly more whites (16.8%) were current smokers than Hispanics (7.7%) or blacks (4.1%) (P<.01).

The highest rates of current daily smoking for the past month were among the whites (12.5%), followed by Hispanics (5.3%) and blacks (2.9%). There were significant differences among all of these groups (P<.01). White youth who were daily smokers also smoked significantly more than Hispanic or black youth (P<.01). Whites had the highest rates of trying to quit smoking, and these rates were significantly greater than those for Hispanics or blacks (P<.01). Notably, blacks had the lowest levels of trying to quit smoking, and these rates were significantly lower than those for other groups (P<.01). Only 9.4% of black smokers had tried to quit in the last six months compared with the 20.5% of whites and 18.8% of Hispanics who had tried quitting.

Overall, the use of spit tobacco is comparatively lower across the country, with only approximately 8.3% of students stating that they have used snuff or chewing tobacco in the past 30 days. White students showed the highest levels of use (14.6%), which were significantly higher than levels for Hispanic (4.9%) and black (3%) students who had used the products within the past 30 days (P<.01). The levels of use by whites were significantly greater than the levels of use by the other groups (P<.01).

Sexual Behaviors

Over half (53%) of the sample stated that they had engaged in sexual intercourse at least once in their lives. Among blacks, 79.7% reported having experienced intercourse, as had 56% of Hispanics. The lowest rates of intercourse were among whites (48.2%) (P<.01). In the preceding three months, 41.4% of the total sample had engaged in intercourse, with blacks (60.5%) having significantly higher levels of sexual activity during that time period than Hispanics (36.4%) or whites (34.4%).

Of those who had been sexually active, 40% had multiple sex partners, and 15% of females and 23% of males stated that they had engaged in sexual intercourse with four or more people. Nearly half (46.7%) of the sexually active adolescents had not used a condom during their last sexual intercourse, and 32.9% admitted that their choice for birth control during their last episode of sexual intercourse was either "none" or "withdrawal."

Of the sexually active females, 20% had been pregnant at least once. Of the sexually active males, 12.6% admitted to having caused at least one pregnancy. Nearly 4% of the males also stated that they "did not know" if they had or had not caused a pregnancy. At least one sexually transmitted diseases has been diagnosed in 7.7% of the females and 4.4% of the males (chi c² = 43.85, 1 df, P<.01).

Dietary Behaviors

Only 15.4% of the sample had eaten any fruits or vegetables (including juices, salads, or cooked vegetables) in the preceding day. Whites (16.1%) had the highest consumption, followed by Hispanics (11.5%) and blacks (9.1%). All differences were significant at the .05 level. Males in all groups consumed more fruits and vegetables than did females, and consump- tion of fruits and vegetables de-clined with each year in school, with 12th-grade students consuming the least of all groups (P<.05).

Approximately one third of the students sampled indicated that they had eaten more than two servings of food considered to be high in fat (hamburgers, French fries, etc.) in the previous day. Among black respondents, 41.1% had eaten more than two servings of these foods in the past day compared with 33.8% of whites and 27.4% of Hispanics. All differences were significant (P<.01).

Physical Activity

A total of 80.6% of respondents indicated that they had engaged in some type of vigorous activity for at least 20 minutes during the past week, 65.8% had engaged in vigorous activity at least three times during the previous week, and 19.6% had done so every day during the previous week. More than half of the sample (57.4%) had walked or bicycled for at least 30 minutes during the previous week, but only 2.3% had done so daily. More females (44.8%) than males (24%) described themselves as either “slightly” or “very” overweight.

Examination of attendance at school physical education classes revealed that only 42.6% of the students sampled had attended on three or more days during school. Of those who attended physical education class, only 51.2% stated that they were actually exercising 20 or more minutes during class.

Discussion

The data presented in this report are alarming. Unacceptably high numbers of the adolescent population of the United States continue to engage in behaviors that place them at significant risk for developing chronic diseases, including cancer, later in life (Table). Tobacco use, a primary cause of many cancers, remains high among all races and both sexes, and few of those who smoke regularly are attempting to quit. It is not surprising that more than 3,000 teenagers become regular smokers each day.² Although the use of spit tobacco is relatively low overall, its use remains high, especially among white males from the South and West. Use of these “smokeless” tobacco products significantly increases the risk of cancer of the mouth, throat, esophagus, and larynx.

The United States is currently faced with a multitude of social and health problems related to the early initiation of sexual intercourse among adolescents. These problems include over one million pregnancies each year,¹¹ over 10 million individuals between 15 and 29 years of age infected each year with sexually transmitted diseases,¹² untold emotional trauma, and related social problems. The cancer risks associated with early sexual activity should not be downplayed. Human papilloma virus infection is associated with cervical cancer among women; thus the frequency of high-risk sexual behaviors noted in these data is cause for concern.

Dietary patterns noted in this study were also cause for concern. Estimates indicate that as many as 35% of total cancer deaths may be related to dietary factors.⁷ Adolescents in this sample did not consume enough fruits and vegetables, and their consumption of high-fat foods was unacceptably high. If continued, these consumption patterns will put today’s youth at significant risk for developing cancers that are associated with a high- fat, low-fiber diet. Interestingly, in a recent American Cancer Society/Gallup survey,¹³ 43% of 12- to 17-year-old adolescents surveyed stated that diet, nutrition, and eating patterns were as important to them as other topics currently taught in schools, and 67% said the same or more amount of time should be spent on these topics as other topics in school.

Generally, teenagers are active, which is to their advantage since so many consume an excessive amount of fat calories a pattern of reduced activity. However, a pattern of re-duced activity, when carried into later life, places the individual at greater risk of hypokinetic diseases and obesity, with concomitant risks for cancer. In fact, individuals who are as much as 40% overweight have an increased risk of several types of cancers, including gall- bladder, colon, endometrial, ovar-ian, breast, cervical, and prostate. ¹⁴

Conclusions

Data from this study clearly demonstrate that American youth are at significant risk of later cancer due to their actions today. More than ever before, youth are in need of knowledge about preventive behaviors. Parents need to be taught appropriate behaviors and must make an effort to model these behaviors in the home. By regularly emphasizing and reinforcing positive health-related values and behaviors, parents can become essential “change agents” and can positively influence their children’s future actions. Concomitantly, community organizations such as churches can join parents in building a solid foundation of prevention.

Schools also play an integral role as they are the primary and most logical setting for sound, structured, learning opportunities. These learning centers “. . . offer the educational framework within which to structure a comprehensive school health education program that provides the time, materials, curriculum, and qualified teachers necessary for cancer prevention and control.”¹⁵ Such programs should contain not only appropriate amounts of health instruction, but also training in food purchase and preparation, lifetime physical activities, drug and sex refusal skills, and self-examination instruction.

Clinicians should talk with their adolescent patients, assess their risks of engaging in various irresponsible behaviors, advise them on appropriate behaviors, and model such behaviors themselves. The medical community must also unite to support prevention through comprehensive school health education in their communities.

If the United States is to meet the Year 2000 Health Objectives,¹⁶ parents, clinicians, schools, and communities must unite to teach and model appropriate health behaviors.

References

1. Kann L, Warren CW, Harris WA, et al. Youth risk behavior surveillance — United States, 1993. MMWR CDC Surveill Summ. 1995;44:1-56.
2. Cancer Facts & Figures - 1997. Atlanta, Ga: American Cancer Society; 1997.
3. Lipsitz JS. The age group. In: Johnson M, ed. Toward Adolescence, The Middle School Years - The Seventy-Ninth Yearbook of the Society for the Study of Education, Part 1. Chicago, Ill: University of Chicago Press; 1980:7.
4. Seffrin JR. Multiple school health interventions: a key to successful cancer education and prevention. J Sch Health. 1989;59:179-180.
5. D'Onofrio CN. Making the case for cancer prevention in the schools. J Sch Health. 1989; 59:225-231.
6. Kolbe LJ. Developing a plan of action to institutionalize comprehensive school health education programs in the United States. J Sch Health. 1993;63:12-13.
7. Doll R, Peto R. The Causes of Cancer: Quantitative Estimates of Available Risks of Cancer in the United States Today. New York, NY: Oxford University Press; 1981.
8. Brener ND, Collins JL, Kann L, et al. Reliability of the Youth Risk Behavior Survey Questionnaire. Am J Epidemiol. 1995;141: 575-580.
9. Siegel S, Castellan NJ Jr. Nonparametric Statistics for the Behavioral Sciences. New York, NY: McGraw-Hill Book Co; 1988.
10. Statistical Package for the Social Sciences. Chicago, Ill: SPSS Inc; 1990.
11. Statistical Abstract of the United States, 1995. Washington, DC: US Department of Commerce, Economics and Statistical Administration, Bureau of the Census; 1996.
12. Centers for Disease Control. Summary of notifiable diseases. MMWR Morb Mortal Wkly Rep. 1994;43:1-80.
13. American Cancer Society. Report of the Gallup Survey on the Values and Opinions of Health Education in the U.S. Public Schools. Atlanta, Ga: American Cancer Society; 1994.
14. Lew EA, Garfinkel L. Variations in mortality by weight among 750,000 men and women. J Chron Dis. 1979;32:563-576.
15. Iammarino NK, Weinberg AD. Cancer prevention in the schools. J Sch Health. 1985;55: 86-95. 16. US Dept of Health and Human Services. Healthy People 2000: National Health Promotion and Disease Prevention Objectives. Washington, DC: US Government Printing Office, US Dept of Health and Human Services Publication No. (PHS) 91-50212; 1990.

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