What shapes the continuum of reproductive isolation? Lessons from Heliconius butterflies

The process by which species evolve can be illuminated by investigating barriers that limit gene flow between taxa. Recent radiations, such as Heliconius butterflies, offer the opportunity to compare isolation between pairs of taxa at different stages of ecological, geographical, and phylogenetic divergence. Here, we report a comparative analysis of existing and novel data in order to quantify the strength and direction of isolating barriers within a well-studied clade of Heliconius Our results highlight that increased divergence is associated with the accumulation of stronger and more numerous barriers to gene flow. Wing pattern is both under natural selection for Müllerian mimicry and involved in mate choice, and therefore underlies several isolating barriers. However, pairs which share a similar wing pattern also display strong reproductive isolation mediated by traits other than wing pattern. This suggests that, while wing pattern is a key factor for early stages of divergence, it may become facultative at later stages of divergence. Additional factors including habitat partitioning, hybrid sterility, and chemically mediated mate choice are associated with complete speciation. Therefore, although most previous work has emphasized the role of wing pattern, our comparative results highlight that speciation is a multi-dimensional process, whose completion is stabilized by many factors.

Differential effects of air conditioning type on residential endotoxin levels in a semi-arid climate

Residential endotoxin exposure is associated with protective and pathogenic health outcomes. Evaporative coolers, an energy-efficient type of air conditioner used in dry climates, are a potential source of indoor endotoxins; however, this association is largely unstudied. We collected settled dust biannually from four locations in homes with evaporative coolers (n=18) and central air conditioners (n=22) in Utah County, Utah (USA), during winter (Jan-Apr) and summer (Aug-Sept), 2014. Dust samples (n=281) were analyzed by the Limulus amebocyte lysate test. Housing factors were measured by survey, and indoor temperature and relative humidity measures were collected during both seasons. Endotoxin concentrations (EU/mg) were significantly higher in homes with evaporative coolers from mattress and bedroom floor samples during both seasons. Endotoxin surface loads (EU/m² ) were significantly higher in homes with evaporative coolers from mattress and bedroom floor samples during both seasons and in upholstered furniture during winter. For the nine significant season-by-location comparisons, EU/mg and EU/m² were approximately three to six times greater in homes using evaporative coolers. A plausible explanation for these findings is that evaporative coolers serve as a reservoir and distribution system for Gram-negative bacteria or their cell wall components in homes.

The diversification of Heliconius butterflies: what have we learned in 150 years?

Research into Heliconius butterflies has made a significant contribution to evolutionary biology. Here, we review our understanding of the diversification of these butterflies, covering recent advances and a vast foundation of earlier work. Whereas no single group of organisms can be sufficient for understanding life's diversity, after years of intensive study, research into Heliconius has addressed a wide variety of evolutionary questions. We first discuss evidence for widespread gene flow between Heliconius species and what this reveals about the nature of species. We then address the evolution and diversity of warning patterns, both as the target of selection and with respect to their underlying genetic basis. The identification of major genes involved in mimetic shifts, and homology at these loci between distantly related taxa, has revealed a surprising predictability in the genetic basis of evolution. In the final sections, we consider the evolution of warning patterns, and Heliconius diversity more generally, within a broader context of ecological and sexual selection. We consider how different traits and modes of selection can interact and influence the evolution of reproductive isolation.

Ecological and genetic factors influencing the transition between host-use strategies in sympatric Heliconius butterflies

Shifts in host-plant use by phytophagous insects have played a central role in their diversification. Evolving host-use strategies will reflect a trade-off between selection pressures. The ecological niche of herbivorous insects is partitioned along several dimensions, and if populations remain in contact, recombination will break down associations between relevant loci. As such, genetic architecture can profoundly affect the coordinated divergence of traits and subsequently the ability to exploit novel habitats. The closely related species Heliconius cydno and H. melpomene differ in mimetic colour pattern, habitat and host-plant use. We investigate the selection pressures and genetic basis underlying host-use differences in these two species. Host-plant surveys reveal that H. melpomene specializes on a single species of Passiflora. This is also true for the majority of other Heliconius species in secondary growth forest at our study site, as expected under a model of interspecific competition. In contrast, H. cydno, which uses closed-forest habitats where both Heliconius and Passiflora are less common, appears not to be restricted by competition and uses a broad selection of the available Passiflora. However, other selection pressures are likely involved, and field experiments reveal that early larval survival of both butterfly species is highest on Passiflora menispermifolia, but most markedly so for H. melpomene, the specialist on that host. Finally, we demonstrate an association between host-plant acceptance and colour pattern amongst interspecific hybrids, suggesting that major loci underlying these important ecological traits are physically linked in the genome. Together, our results reveal ecological and genetic associations between shifts in habitat, host use and mimetic colour pattern that have likely facilitated both speciation and coexistence.

Factors associated with attrition and success in a worksite wellness telephonic health coaching program

OBJECTIVES

This study identifies factors associated with attrition and improvements in body mass index (BMI) in a telephonic health coaching program.

METHODS

A cohort study design was used with 6,129 employees aged 21-88 years, enrolled in telephonic health coaching sometime during 2002 through 2008.

RESULTS

Attrition through 3, 6 and 12 months of follow-up was 13%, 17% and 36%, respectively. Those currently making changes in physical activity or nutrition had the highest BMI (kg/m2), lowest levels of exercise and the poorest overall health at baseline. They were also most likely to continue with health coaching through 12 months. Those not ready to make changes at this time or having maintained an appropriate level of physical activity or nutrition for more than six months were least likely to continue with health coaching through 12 months. They also had the lowest BMI, highest levels of exercise and the best overall health. Among those continuing with health coaching through 12 months, the percent decrease in BMI between baseline and 12 months was: 1.5% for normal weight, 2.7% for overweight, 4.1% for class I & II obesity and 7.2% for class III obesity; 4.3% for high confidence to lose weight, 3.5% for medium confidence to lose weight and 3.1% for low confidence to lose weight; and 3.8% for very good or good general health, 4.5% for average general health and 6.8% for poor/very poor general health.

CONCLUSIONS

Attrition in the telephonic health coaching program is greatest among those least in need of behavior change. Of those who continued in the program, the greatest decrease in BMI occurred in those in greatest need for behavior change.

KEYWORDS

Behavior change, BMI, interactive health coaching, readiness to change, self-efficacy, weight.

Sectors of the Russian economy that would benefit from reduced cigarette sales

BACKGROUND

Cigarette companies argue that tobacco control measures will harm the Russian economy. Research in other countries has refuted this claim.

OBJECTIVE

To identify how current and former smokers would (or did) spend their cigarette money if (or when) they quit smoking.

METHODS

A nationwide face-to-face survey of 1599 participants aged 18 years and older in 128 cities was conducted in Russia during May 2008 by the Russian Levada Analytical Center.

RESULTS

In all, 10% of respondents were former smokers and 33% were current smokers. Respondents indicated that they would spend their cigarette money on selected items if they quit. These items, from most to least common are groceries, recreation, housing, clothing, transportation, healthcare and savings. The ways that cigarette money would be spent in the absence of smoking significantly differed according to smoking status, gender, age, education, income, rural versus urban residency and geographic region.

CONCLUSIONS

Tobacco control may benefit the Russian economy by producing healthier workers and because the money that would have been used for cigarettes would be shifted primarily to groceries, recreation, housing and clothing.

Employee weight management through health coaching

OBJECTIVE

This study will evaluate the effectiveness of an interactive health coaching intervention at lowering weight.

METHODS

The study involved 5405 overweight or obese employees aged 18-85, who entered the program sometime during 2001-2008.

RESULTS

Average body mass index (BMI) significantly decreased from 32.1 at baseline to 31.4 at 3 months, 31.0 at 6 months, and 30.6 at 12 months. Decreasing BMI was more pronounced in older age groups and among women, those using weight loss medication, those with higher BMI, and those with higher motivation and confidence to make behavior changes. When the effects of these variables on the decreasing trend in BMI were simultaneously estimated, only baseline classifications of BMI, health status, and confidence remained significant. Change in BMI through 12 months was -0.7% for those with normal weight, -2.0% for overweight, -3.6% for obese, and -7.1% for morbidly obese individuals at baseline. Among morbidly obese individuals, decrease in BMI through 12 months was -7.6% for those with "high" confidence to lose weight at baseline vs -4.4% for those with low confidence. Better health status at baseline was also related to more pronounced weight loss.

CONCLUSION

Interactive health coaching significantly lowered BMI among participants through 3, 6, and 12 months of follow-up.

Perceived effectiveness of counselling patients about smoking among medical students in Amman, Jordan

We identified the prevalence of smoking and perceived effectiveness of physicians counselling patients about smoking among 340 1st and 4th year medical students in Amman, Jordan. Smoking prevalence was 26% for males and 7% for females, similar to that of their peers in the general population. Smokers and male students were less likely to believe it is wrong for physicians to smoke in front of patients or that smoking policy or physician interaction with patients can influence smoking practices. Students believed that physicians can more effectively prevent smoking than influence patients to stop smoking. Student training on how to effectively counsel patients about smoking prevention and cessation is warranted.

The effects of an intensive lifestyle modification program on sleep and stress disorders

BACKGROUND

To determine if a lifestyle change program can modify behavior to reduce sleep and stress disorders.

METHODS

Analyses are based on 2,624 individuals aged 30 to 80 years from the Rockford, Illinois metropolitan area who completed a lifestyle evaluation at baseline and again after four weeks, following participation in a 40-hour educational course given over a four-week period. Participants receive instruction on the importance of making better lifestyle choices related to making long-term improvements in nutrition and physical activity and they learn ways to improve sleep and reduce stress in their lives.

RESULTS

Significant percent decreases were observed in the number experiencing selected sleep or stress disorders from baseline to four weeks later for "sleeps restlessly" (-59%), "suffers from insomnia" (-64%), "feels under pressure" (-37%), "easily emotionally upset" (-52%), and "feels fearful or depressed" (-61%). Experiencing a selected sleep or stress disorder after four weeks among those who had the disorder at baseline was significantly more likely in those not physically active and/or not having lowered their BMI after four weeks. Changes in alcohol consumption and smoking did not significantly contribute to changes in the disorders. Those who failed to lower their coffee/tea use after four weeks were significantly more likely to have a sleep disorder and be easily emotionally upset.

CONCLUSIONS

Changes in lifestyle behaviors after attending an educational program significantly reduced sleep and stress disorders in as little as four weeks, primarily explained by decreasing BMI and/or increasing exercise.

Sit to stand transfer: performance in rising power, transfer time and sway by age and sex in senior athletes

OBJECTIVE

To observe the differences in performance variables of the sit to stand transfer (as measured on the NeuroCom Balance Master) in a population of senior athletes.

METHOD

A convenience sample of 173 subjects aged 50 years and older. Data were obtained from voluntary participation in a health fair offered at the annual Huntsman World Senior Games in St George, Utah, USA. All sit to stand tests were performed on the NeuroCom Balance Master. The measured parameters were weight transfer time (WTT), rising power (force exerted to rise), and centre of gravity sway (COG sway) during the rising phase.

RESULTS

A significant difference was found between stratified age groups (50-64 and 65+ years) on rising power. There was also a sex difference in rising power. No significant differences were found in weight transfer time or COG sway.

CONCLUSION

While rising power decreases with increasing age in senior athletes, WTT and COG sway remain similar regardless of age or sex. The maintenance of these other two variables (WTT and COG sway) may be attributable to physical activity and/or participation in sport.

Trends in tobacco smoking among adolescents in Lyon, France

To provide information that may promote more effective cancer prevention, we identified factors associated with regular smoking among adolescents in Lyon, France. School grades where these factors began to influence regular smoking were also identified. Seven consecutive cross-sectional anonymous surveys were conducted in three public schools, beginning in grade 6ème (average age 11.5 years) in 1993 and ending in grade Terminale (average age 17.4 years) in 1999. All classes in each respective grade were surveyed, with 3650 completed questionnaires for all years combined. Prevalence of current regular smoking is presented according to school grade for 17 variables identified as significantly related to regular smoking in a multivariate logistic regression analysis. Important factors associated with regular smoking were identified as early as grade 6ème and included not viewing the taking care of one's health as important, not eating breakfast regularly, associating with groups where smoking occurs, having a best friend who smokes, and having a brother and/or sister who smokes. Not regularly reading was first associated with an increased risk of regular smoking in grade 5ème. Not living with both parents, alcohol drinking, episodes of drunkenness, illicit drug use, and sexual relationships were positively associated with regular smoking in the middle and later grades, when these questions were first asked. Not playing sports and not playing with computers were initially associated with an increased risk of regular smoking in grade 3ème.

Demographics and health-related factors of men receiving prostate-specific antigen screening in Utah

BACKGROUND

Identifying who is pursuing prostate-specific antigen (PSA) screening for prostate cancer is prerequisite to effectively influencing participation in PSA screening and educating people about potential screening implications and personal risk. This paper describes the relationship between select demographic and health-related factors with PSA screening.

METHODS

Analysis was based on 1,293 men age 40 years or older who responded to a cross-sectional random telephone survey involving 12 health districts in the state of Utah from June 1 to August 31, 1996. Independent variables were current age, race, marital status, education, household income, medical insurance, level of physical activity, intake of fruits and vegetables, receipt of psychiatric help, religious preference, church attendance, general health status, and employment.

RESULTS

Forty-eight percent of respondents reported having had a PSA in the past year. PSA screening in the previous year significantly increased and leveled off with age: 23.9% for ages 40-49, 51.4% for ages 50-59, 67.4% for ages 60-69, and 67.0% for ages 70+. After adjusting for age, only marital status and medical insurance were significantly related to PSA screening, with medical insurance having the largest effect. Approximately 50.6% married men and 33.5% unmarried men had a PSA in the past year. Percentages for insured and uninsured men were 49.4 and 16.6%, respectively.

CONCLUSION

A substantial portion of elderly men, particularly those who are married and medically insured, have had a PSA test in the past year. This information makes it possible to more effectively influence participation in PSA screening and educate people about potential screening implications and personal risk.

Measuring the public health burden of cancer in the United States through lifetime and age-conditional risk estimates

PURPOSE

Effects of an aging population in the United States on lifetime and age-conditional risk estimates of developing site-specific cancers are identified and the potential role these statistics play in monitoring disease burden discussed.

METHODS

Risk estimates were derived by applying cross-sectional population-based incidence rates of cancer and mortality rates from other causes to a hypothetical cohort. The cohort was aged through a double decrement life table to determine the expected proportion of the population that would develop the disease.

RESULTS

Despite black men having higher invasive cancer incidence rates than white men, and black and white women having similar rates, because of the better life expectancy among whites lifetime risk estimates of developing cancer are higher for whites than blacks: 45.5% in white men, 40.4% in black men, 39.2% in white women, and 32.4% in black women based on 1995-97 data. White men experience higher 10-year cancer risk than black men in only bladder cancer, non-Hodgkin's lymphomas (NHL), and leukemia. White women tended to show a greater risk than black women for cancers of the breast, corpus uteri, ovary, NHL, and leukemia. For both whites and blacks, the 10-year risk of lung cancer ranks first among men aged 40, ranks second to prostate cancer for men aged 50, 60, and 70, and ranks second to breast cancer for women aged 40, 50, 60, and 70.

CONCLUSIONS

Lifetime and age-conditional risk measures reflect both changes in the disease incidence rates and age distribution over calendar time such that they are useful for monitoring the disease burden in the population. Even if cancer rates remain stable or fall, it is possible for the cancer burden, as reflected by lifetime and age-conditional risk estimates, to increase due to the aging population.

Religious preference, church activity, and physical exercise

BACKGROUND

Utah has the highest percentage of physically active adults in the United States. It also has a high percentage of religiously active people. About 90% of the adult population has a religious preference and 62% of those individuals attend church weekly. This study evaluates the relationship between religious preference, church attendance, and physical activity.

METHODS

Analysis is based on 6,188 adult respondents ages 18 years and older to a cross-sectional random telephone survey involving 12 health districts in the state of Utah from June 1 to August 31, 1996.

RESULTS

Within religious groups, those attending church weekly were more likely to exercise than individuals attending church less than weekly. About 70% of Utah consists of members of the Church of Jesus Christ of Latter-day Saints (LDS). LDS attending church less than weekly were least physically active in Utah. The percentages of those exercising vigorously at least 20 min three times per week were 52.3% (LDS who attend church weekly), 44.5% (LDS who attend church less than weekly), 57.6% (non-LDS who attend church weekly), 54.3% (non-LDS who attend church less than weekly), and 53.1% (no religious preference) (P = 0.0070). When adjustment was made for age, smoking status, education, marital status, and general health, differences in exercise between church activity levels within religious groups became insignificant. Smoking and general health have the greatest influences on the relationship between religious preference, church attendance, and exercise. LDS were significantly less physically active than non-LDS in the adjusted model.

CONCLUSIONS

Although differential smoking levels and general health status explained differences between church activity levels within religious groups, lower levels of exercise among LDS versus non-LDS could not be explained and require further study.

Partitioned prostate cancer prevalence estimates: an informative measure of the disease burden

STUDY OBJECTIVES

Public health burden of disease is often measured using prevalence statistics. Prevalence of invasive prostate cancer in the United States is presented according to age at diagnosis, time from diagnosis, geographical area, and two races (white and black).

DESIGN

Invasive prostate cancer data from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute is used for obtaining prevalence estimates.

MAIN RESULTS

Despite falling prostate cancer incidence rates, the prevalence of this disease continues to rise for both white and black men. Black men diagnosed at ages 60 years and older experience lower levels of prevalence of prostate cancer than white men because of poorer survival and a smaller proportion of black men living to older ages where the disease becomes common. Black men require fewer years of follow up than white men to capture over 99% of prevalent cases (that is, 14 years versus 16 years, respectively). Prevalence estimates in the United States are traditionally based on Connecticut data. On 1 January 1997, United States prostate cancer prevalence estimates based on Connecticut are overestimated for white men and underestimated for black men.

CONCLUSIONS

Partitioned prevalence estimates may provide a more meaningful and informative measure of the disease burden than conventional prevalence estimates. Prostate cancer prevalence estimates based on SEER rather than Connecticut data are better representative of the United States.

Factors associated with no surgery or radiation therapy for invasive cervical cancer in Black and White women

This paper identifies the proportion of invasive cervical cancer cases that do not receive cancer-directed surgery or radiation; assesses the influence of race, stage, age, grade, nodal status, histology, and co-morbid cancer primaries on receipt of treatment; and considers reasons why cancer-directed therapy is not received. We analyzed data for 8,119 patients with invasive cervical cancer from eleven population-based tumor registries in the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute, 1992-96. Approximately 8.03% of Whites and 11.64% of Blacks did not receive surgery or radiation therapy (no therapy). The percentage of cases receiving no therapy were greatest for unstaged cases, and for cases with unknown grade or unknown lymph node status. Adjusted odds of no therapy significantly increased with distant and unstaged disease (vs local stage) and older age (vs 0-39) at diagnosis; unknown grade (vs well differentiated); or unknown lymph node (vs no lymph node) status. Black cases were more likely to be unstaged and unstaged cases are more likely to not receive therapy. Blacks were more likely than Whites not to receive surgery because it was not recommended, contraindicated due to other conditions, or refused. Of cases refusing radiation, 53.85% of Whites and 83.33% of Blacks refused surgery, and of women refusing surgery, 22.58% of Whites and 50% of Blacks refused radiation. Stage, age, grade, and lymph node status directly influence receipt of treatment. Race influences receipt of treatment indirectly through stage. Reasons why therapy was not received (eg, not recommended, refused) differ according to race and stage at diagnosis.

Prevalence corrected hysterectomy rates and probabilities in Utah

PURPOSE

A life table method is used for correcting hysterectomy rates and probabilities for prevalent cases of hysterectomies in the population. Both corrected and conventional hysterectomy rates and probabilities are reported.

METHODS

Hysterectomy prevalence estimates are derived from cross-sectional hysterectomy and mortality using a life table method. Analysis is based on the Utah Hospital Discharge Data Base and State death certificates.

RESULTS

Hysterectomy rates are strongly influenced by age, reaching 150 per 10,000 for ages 45-49 years. The corresponding corrected hysterectomy rate is 196. Differences between the corrected and uncorrected cause-specific hysterectomy rates tend to be most pronounced at their peaks, particularly later in life where the prevalence of hysterectomy is greatest. Probability of hysterectomy approaches slightly above 35% over the life span, whereas the corrected hysterectomy probability approaches 43%. Probability of hysterectomy in the next 10 years is 12.9% for women aged 35 years and 11.7% for women aged 45 years. Corresponding corrected hysterectomy probabilities are 14.3 and 15.1. Higher prevalence of hysterectomy in later ages explains the reverse in magnitude of the rates when the correction is applied to the hysterectomy rates.

CONCLUSIONS

Conventional hysterectomy rates are underestimated, particularly in older age groups. A prevalence correction of the rates and probabilities is necessary to fully understand the potential health related consequences and impact of this medical procedure in the population.

The relationship of perceived age and sales of tobacco and alcohol to underage customers

The ability of store clerks to estimate the age of their customers is critical in preventing illegal sales of tobacco and alcohol to underage individuals. To avoid illegal sales of tobacco products to minors, the Food and Drug Administration created a policy in 1997 requiring store clerks to request identification of anyone perceived to be underage 27. A similar age standard has not been implemented for alcohol. The purpose of this article is to assess whether age 27 is adequate for minimizing tobacco sales to those under age 18 and whether this age is also a useful standard for minimizing illegal alcohol sales to those under age 21. The analysis is based on age estimates from 49 gas station and convenience store clerks. Each clerk estimated ages of 45 people filmed on video whose actual ages ranged from 15 to 29. T-tests, analysis of variance, contingency tables and logistic regression were used to analyze the data. Store clerks found it more difficult to estimate ages of female customers than male customers. In addition, the store clerks significantly underestimated age of male customers under 18 and of female customers under 21. In contrast, the clerks significantly overestimated age of customers 21 years and older. Among underage customers, the store clerks' age, gender, work experience, education, and training in requesting identification had no influence on ability to judge age, nor did it have a strong influence on whether an underage customer was considered 18 or older or 21 or older. The results suggest that age 27 is adequate for minimizing illegal tobacco sales. Adoption of a similar or slightly older age may be appropriate for minimizing illegal alcohol sales.

Nonaggressive management of White and Black prostate cancer patients in the United States

Appropriate treatment for prostate cancer is controversial because of the lack of information from randomized clinical trials indicating the benefits of one treatment over another. Watchful waiting or conservative management remains an alternative for this disease. This paper assesses the extent to which White and Black prostate cancer patients in the USA choose nonaggressive therapy. Nonaggressive therapy is defined as patients not receiving cancer-directed surgery or radiation, or that undergo a transurethral resection of the prostate (TURP)/simple prostatectomy but no radiation. Of 112,445 prostate cancer patients diagnosed in 1992-1996, 40% Whites and 46% Blacks were not aggressively treated. Approximately 28% Whites and 33% Blacks did not receive cancer-directed surgery or radiation, and 12% Whites and 13% Blacks underwent a TURP/simple prostatectomy but no radiation. Stage, histologic grade and age at diagnosis, race (White and Black), and number of cancer primaries each significantly influence how patients are managed. Black patients are more likely than White patients to forego aggressive therapy, even after adjusting for less preferential stage and histologic grade at diagnosis, as well as differences in age and number of cancer primaries. Explanations for this result deserve further consideration. Prostate Cancer and Prostatic Diseases (2000) 3, 94-99

Explaining the difference in prostate cancer mortality rates between white and black men in the United States

OBJECTIVES

Black men have a twofold increased risk of dying of prostate cancer compared to white men. We assessed the extent to which differences in stage and grade at diagnosis, age, multiple primary cancers, and the first course of cancer-directed therapy influence the likelihood of prostate cancer death among diagnosed cases.

METHODS

Incidence-based mortality (IBM) is a method that involves tracking disease cases from diagnosis to death, such that the mortality event is linked to factors identified with the disease at the time of diagnosis (eg, tumor stage and grade). We applied the IBM method to prostate cancer data from the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute.

RESULTS

Of men diagnosed with prostate cancer, blacks have a significantly greater chance of dying from the disease than do whites. However, once adjustment has been made for stage and grade at diagnosis, age, number of primary cancers, and initial treatment, no difference in the likelihood of prostate cancer mortality between the two races was found. Differences in stage and grade at diagnosis, age, number of primary cancers, and initial treatment each contributed significantly to the greater chance of dying of prostate cancer for black men than for white men.

CONCLUSIONS

The results of IBM analysis suggest that black men do not have a statistically greater chance of prostate cancer mortality than white men after adjusting for differences in stage and grade, age, number of primary cancers, and treatment. Later stage at diagnosis is the primary reason for the higher likelihood of prostate cancer mortality among black men compared to white men.

Cancer prevalence estimates based on tumour registry data in the Surveillance, Epidemiology, and End Results (SEER) Program

BACKGROUND

The Connecticut Tumor Registry (CTR) has collected cancer data for a sufficiently long period of time to capture essentially all prevalent cases of cancer, and to provide unbiased estimates of cancer prevalence. However, prevalence proportions estimated from Connecticut data may not be representative of the total US, particularly for racial/ethnic subgroups. The purpose of this study is to apply the modelling approach developed by Capocaccia and De Angelis to cancer data from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute to obtain more representative US site-specific cancer prevalence proportion estimates for white and black patients.

METHODS

Incidence and relative survival were modelled and used to obtain estimated completeness indices of SEER prevalence proportions for all cancer sites combined, stomach, cervix uteri, skin melanomas, non-Hodgkin's lymphomas, lung and bronchus, colon/rectum, female breast, and prostate. For validation purposes, modelled completeness indices were computed for Connecticut and compared with empirical completeness indices (the ratio of Connecticut based prevalence proportion estimates using 1973-1993 data to 1940-1993 data). The SEER-based modelled completeness indices were used to adjust SEER prevalence proportion estimates for white and black patients.

RESULTS

Model validation showed that the adjusted SEER cancer prevalence proportions provided reasonably unbiased prevalence proportion estimates in general, although more complex modelling of the completeness indices is necessary for female cancers of the colon, melanoma, breast, cervix, and all cancers combined. The SEER-based cancer prevalence proportions are incomplete for most cancer sites, more so for women, whites, and at older ages. For all cancers combined, prevalence proportions tended to be higher for whites than blacks. For the site-specific cancers this was true for stomach, prostate, cervix uteri, and lung and bronchus (men only). For colon/rectal cancers the prevalence proportions were higher for blacks through ages 59 (men) and 64 (women), and then for the remaining ages they were higher for whites. Prevalence proportions were lowest for stomach cancer and highest for prostate and female breast cancers. Men experienced higher prevalence proportions than women for skin melanomas, non-Hodgkin's lymphomas, lung and bronchus, and colon/rectal cancers.

CONCLUSION

The modelling approach applied to SEER data generally provided reasonable estimates of cancer prevalence. These estimates are useful because they are more representative of cancer prevalence than previously obtained and reported in the US.

Measuring the projected public health impact of lung cancer through lifetime and age-conditional risk estimates

PURPOSE

Lifetime and age-conditional probability (risk) estimates of developing lung cancer in the United States are presented by age, race, and gender. Effects on the risk estimates of an aging population and changing tobacco use are identified.

METHODS

Risk estimates were derived by applying cross-sectional, population-based incidence rates of malignant lung cancer and mortality rates from other causes to a hypothetical cohort. The cohort was aged through a double-decrement life table to determine the expected proportion of the population that would develop the disease across age intervals. Incidence and mortality data were obtained from the Surveillance, Epidemiology, and End Results (SEER) Program and the National Centers for Health Statistics, respectively.

RESULTS

Among all cancers, risk estimates of developing lung cancer within 10 years, conditioned on being free of the disease at age 50, 60, or 70, ranked second to prostate cancer for men and second to breast cancer for women. For men, despite higher incidence rates of lung cancer for blacks than whites across most age groups, the risk of developing this disease over the life-span becomes similar, because white men are more likely to live to older ages where lung cancer is common. For women, lung cancer incidence rates are similar between Whites and Blacks, but an older age distribution among white women explains their greater lifetime risk of being diagnosed with the disease. Changes in the age distribution between the mid 1970s and the mid 1990s had little impact on the short-term risk estimates of developing lung cancer for younger ages but had a large influence on long-term risk estimates, particularly for the older age groups.

CONCLUSIONS

Declining lung cancer among younger age groups may be attributed to declining tobacco use among the cohorts, but several more years may be required before the trends begin to fall in older age groups, particularly in women. In the meantime, an aging population is contributing to more people being diagnosed with lung cancer. Consequently, the projected risk of developing lung cancer will remain high for several years to come.

Trends in mortality rates in patients with prostate cancer during the era of prostate specific antigen screening

PURPOSE

We assess the influence of prostate specific antigen screening on trends in mortality rates in patients with prostate cancer.

MATERIALS AND METHODS

The incidence based mortality method was applied to prostate cancer data from the Surveillance, Epidemiology, and End Results Program. This method links data on patients diagnosed with cancer to vital status and cause of death, such that mortality can be evaluated by factors associated with disease at diagnosis. Prostate and nonprostate cancer mortality rates were evaluated according to patient age at death, disease stage and grade at diagnosis, race and whether additional cancers involving other sites were present.

RESULTS

Mortality due to prostate cancer decreased from 37% in 1988 to 30% in 1995 largely as a result of a sharp increase in nonprostate cancer mortality rates. The overall trend in prostate cancer mortality rates increased from 1988 through 1992 and then decreased. The increase and decrease in rates occurred across categories of age, race, grade and number of cancer primaries. However, the increase in rates did not occur in distant staged cases, nor did the subsequent decrease in rates occur in nondistant staged cases.

CONCLUSIONS

Prostate specific antigen screening influenced the increase and decrease in prostate cancer mortality rates.

Partitioning linear trends in age-adjusted rates

OBJECTIVE

Surveillance of chronic diseases includes monitoring trends in age-adjusted rates in the general population. Statistics that are calculated to describe and compare trends include the annual percent change and the percent change for a specified time period. However, it is also of interest to determine the contribution specific diseases make to an overall trend in order to better understand the impact of interventions and changes in the prevalence of risk factors. The objective here is to provide a method for partitioning a linear trend in age-adjusted rates into disease-specific components.

METHODS

The method presented is based on linear regression. The decreasing trend in age-adjusted cancer mortality rates for the total United States during the period 1991-96 is analyzed to illustrate the method.

RESULTS

Trends in mortality for cancers of the colon/rectum, breast, lung/bronchus, and prostate are found to be responsible for 75% of the decreasing trend in cancer mortality.

CONCLUSIONS

It is possible to partition an overall trend in age-adjusted rates under the assumption that it and the trends for all mutually exclusive and exhaustive subgroups of interest are linear.

Monitoring progress against cancer with age-adjusted rates and trends: what role does the standard population play?

BACKGROUND

Age-adjusted rates and statistical measures used to assess these rates are commonly used in cancer research to monitor progress against this disease. Trends in age-adjusted rates and related summary statistics may depend on the standard population used for age adjustment. Hence, knowledge of how the selected standard population influences such rates is essential for analysis and interpretation of the results.

METHODS

The current paper evaluates age-specific and age-adjusted trends for the three leading causes of cancer mortality in the United States: lung and prostate cancers for males, and lung and breast cancers for females.

RESULTS, CONCLUSIONS

The analysis shows that the choice of the standard population for age adjustment of the rates can influence one's perception of the progress being made against cancer.

An examination of common coping strategies used to combat driver fatigue

Driver fatigue is recognized as an important highway safety risk. Many organizations have published recommendations for coping with driver fatigue. The authors explored the effectiveness of 10 common coping strategies, using a case-controlled design to examine the use of coping strategies among a random sample of college students (N = 301). The students were questioned about their use of coping strategies for driver fatigue and their record of having experienced a dozing-related incident. Odds ratios were calculated and 4 strategies--taking a walk, drinking caffeinated beverages, stopping for a nap, and chewing ice--were found to predict an incident. Three other strategies, snacking, rolling the window down, and talking with a passenger, were found to be protective.

Role of transurethral resection of the prostate in population-based prostate cancer incidence rates

The extensive pool of asymptomatic prostate disease in the population, which increases substantially with age, suggests that the frequent use of transurethral resection of the prostate (TURP) in recent decades has had a large effect on prostate cancer incidence. The authors identified the effect of TURP-detected prostate cancer on the observed incidence rates between 1973 and 1993 for men aged 65 years and older. They linked population-based cancer registry data from the Surveillance, Epidemiology, and End Results Program to Medicare records between 1986 and 1993 to determine whether a TURP occurred sufficiently close to the time of a prostate cancer diagnosis for them to assume that it led to the diagnosis. TURP-detected cases prior to 1986 were calculated using an indirect method that involved multiplying the TURP procedure rate in the general population (from the National Hospital Discharge Survey) by estimates of the proportion of TURPs resulting in a prostate cancer diagnosis (from Medicare data and the literature). TURP explained much of the observed increase in overall prostate cancer incidence between 1973 and 1986 and possibly all of it in men aged 70 years and older. However, its influence on the trend and overall magnitude of the rates diminished between 1987 and 1993. The changing role of TURP in detecting prostate cancer is attributed to changes in medical technology and screening practices. The declining influence of TURP on prostate cancer incidence is likely to have continued beyond the study period due to the recent introduction and increasing use of medications for treating obstructive uropathy.

Conditional survival among patients with carcinoma of the lung

OBJECTIVE

One- and 5-year probabilities of survival or death change once a patient has already survived > or = 1 year after diagnosis. The current paper reports these probabilities for lung cancer patients according to histologic subtype, stage, and age at diagnosis.

METHODS

Cumulative observed survival rates were calculated and compared among 95,283 patients with histologically confirmed lung cancer (diagnosed from 1983 to 1992 and followed through 1995) by the life-table method using population-based tumor registries participating in the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute. On the basis of the cumulative survival estimates, we derived the probability of death in the next year, conditioned on having already survived to the start of the year (annual hazards), and the probability of survival conditioned on having already survived > or = 1 year (conditional survival). These rates were reported according to histologic subtype, stage, and age groups.

RESULTS

At the time of diagnosis, annual hazard rates differ greatly among histologic subtypes. However, by 5 years after diagnosis, the rates become similar. Bronchioloalveolar carcinoma displays the lowest annual hazards and small-cell carcinoma displays the highest annual hazards. Stage-age subcategories within histologic subtypes continue to show large differences in annual hazard rates. Five-year conditional survival probabilities are also reported, providing survival information that is consistent to that obtained from the annual hazards.

CONCLUSIONS

One- and 5-year prognosis for lung cancer patients is influenced by years already survived and histology, stage, and age at diagnosis. Annual hazards and conditional survival provides useful and more relevant information than conventional survival estimates for patients and their physicians. These statistics can be directly obtained from cumulative survival estimates and should be more widely reported.

Cancer surveillance series: interpreting trends in prostate cancer--part II: Cause of death misclassification and the recent rise and fall in prostate cancer mortality

BACKGROUND

The rise and fall of prostate cancer mortality correspond closely to the rise and fall of newly diagnosed cases. To understand this phenomenon, we explored the role that screening, treatment, iatrogenic (i.e., treatment-induced) deaths, and attribution bias (incorrect labeling of death from other causes as death from prostate cancer) have played in recent mortality trends.

METHODS

Join point regression is utilized to assess the recent rise and fall in mortality and the relationship of total U.S. trends to those areas served by the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Cancer Registry Program. Incidence-based mortality (IBM) is estimated with the use of prostate cancer data from the SEER Program to partition (from overall prostate cancer mortality trends) the contribution of cases diagnosed since the widespread use of prostate-specific antigen (PSA) testing starting in 1987. IBM is also used to examine the contribution of stage at diagnosis to the recent prostate cancer mortality trends.

RESULTS

IBM for cases diagnosed since 1987 rose above the pre-1987 secular (i.e., background) trend, peaked in the early 1990s, and almost returned to the secular trend by 1994. This rise and fall of IBM track with the pool of prevalent cases diagnosed within the prior 2 years. IBM for cases diagnosed with metastatic disease fell starting in 1991, while IBM for those diagnosed with localized/regional disease was relatively flat.

CONCLUSIONS

The rise and fall in prostate cancer mortality observed since the introduction of PSA testing in the general population are consistent with a hypothesis that a fixed percent of the rising and falling pool of recently diagnosed patients who die of other causes may be mislabeled as dying of prostate cancer. The decline in IBM for distant stage disease and flat IBM trends for localized/regional disease provide some evidence of improved prognosis for screen-detected cases, although alternative interpretations are possible.

Cancer surveillance series: interpreting trends in prostate cancer--part III: Quantifying the link between population prostate-specific antigen testing and recent declines in prostate cancer mortality

BACKGROUND

The objective of this study was to investigate the circumstances under which dissemination of prostate-specific antigen (PSA) testing, beginning in 1988, could plausibly explain the declines in prostate cancer mortality observed from 1992 through 1994.

METHODS

We developed a computer simulation model by use of information on population-based PSA testing patterns, cancer detection rates, average lead time (the time by which diagnosis is advanced by screening), and projected decreased risk of death associated with early diagnosis of prostate cancer through PSA testing. The model provides estimates of the number of deaths prevented by PSA testing for the 7-year period from 1988 through 1994 and projects what prostate cancer mortality for these years would have been in the absence of PSA testing.

RESULTS

Results were generated by assuming a level of screening efficacy similar to that hypothesized for the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. Under this assumption, the projected mortality in the absence of PSA testing continued the increasing trend observed before 1991 only when it was assumed that the mean lead time was 3 years or less. Projected mortality trends in the absence of PSA screening were not consistent with pre-1991 increasing trends for lead times of 5 years and 7 years.

CONCLUSIONS

When screening is assumed to be at least as efficacious as hypothesized in the PLCO trial, it is unlikely that the entire decline in prostate cancer mortality can be explained by PSA testing based on current beliefs concerning lead time. Only very short lead times would produce a decline in mortality of the magnitude that has been observed.

Cancer surveillance series: interpreting trends in prostate cancer--part I: Evidence of the effects of screening in recent prostate cancer incidence, mortality, and survival rates

BACKGROUND

The prostate-specific antigen test was approved by the U.S. Food and Drug Administration in 1986 to monitor the disease status in patients with prostate cancer and, in 1994, to aid in prostate cancer detection. However, after 1986, the test was performed on many men who had not been previously diagnosed with prostate cancer, apparently resulting in the diagnosis of a substantial number of early tumors. Our purpose is to provide insight into the effect of screening on prostate cancer rates. Detailed data are presented for whites because the size of the population allows for calculating statistically reliable rates; however, similar overall trends are seen for African-Americans and other races.

METHODS

Prostate cancer incidence data from the National Cancer Institute's Surveillance, Epidemiology, and End Results Program and mortality data from the National Center for Health Statistics were analyzed.

RESULTS/CONCLUSIONS

The following findings are consistent with a screening effect: 1) the recent decrease since 1991 in the incidence of distant stage disease, after not having been perturbed by screening; 2) the decline in the incidence of earlier stage disease beginning the following year (i.e., 1992); 3) the recent increases and decreases in prostate cancer incidence and mortality by age that appear to indicate a calendar period effect; and 4) trends in the incidence of distant stage disease by tumor grade and trends in the survival of patients with distant stage disease by calendar year that provide suggestive evidence of the tendency of screening to detect slower growing tumors.

IMPLICATIONS

The decline in the incidence of distant stage disease holds the promise that testing for prostate-specific antigen may lead to a sustained decline in prostate cancer mortality. However, population data are complex, and it is difficult to confidently attribute relatively small changes in mortality to any one cause.

The relationship of socio-economic status and access to minimum expected therapy among female breast cancer patients in the National Cancer Institute Black-White Cancer Survival Study

Black women are more likely to be diagnosed with later stage breast cancer and have higher mortality rates from breast cancer than white women. To determine whether cancer treatment varies for white and black women, we analyzed data from the National Cancer Institute (NCI) Black-White Cancer Survival Study (BWCSS). Data from hospital medical records, central review of histology slides, and patient interviews on 861 breast cancer cases (in situ and invasive) were examined. Minimum expected therapy was defined for each disease stage as a basic minimum course of treatment that incorporated current practice, state-of-the-art knowledge, and recommendations advanced by NIH Consensus Conferences up to and including the one held in 1985. Patients in this study were diagnosed during 1985-1986. Using logistic regression techniques, those who received at least the minimum expected therapy were compared to those who did not. Thirty-six percent of the patients with late stage disease did not receive minimum expected therapy compared to four percent of the patients with early stage disease. Older women and women with no usual source of care were significantly less likely to receive minimum expected therapy. Overall, 21% of black women did not receive minimum expected therapy compared to 15% of white women.

Survival and treatment for colorectal cancer Medicare patients in two group/staff health maintenance organizations and the fee-for-service setting

The current study compares treatment use and long-term survival in colorectal cancer patients between Medicare beneficiaries enrolled in two large prepaid group/staff health maintenance organizations (HMOs) and the fee-for-service (FFS) setting. The study is based on 15,352 colorectal cancer cases diagnosed between 1985 and 1992 and followed through 1995. Survival differences between the HMO and FFS cases were assessed using Cox regression. Treatment differences were evaluated using logistic regression. HMO cases had a lower overall mortality than did FFS cases but not a significantly lower colorectal cancer-specific mortality. Use of surgical resection was similar between HMO and FFS cases. However, rectal cancer cases in the HMOs were more likely to receive postsurgical radiation therapy than FFS cases. Superior overall survival in the HMOs may be the result of increased colorectal cancer screening, greater use of adjuvant therapies, and selection of healthier individuals.

Prostate cancer treatment and ten-year survival among group/staff HMO and fee-for-service Medicare patients

OBJECTIVE

To compare treatment patterns and the ten-year survival of prostate cancer patients in two large, nonprofit, group/staff HMOs to those of patients receiving care in the fee-for-service health setting.

DATA SOURCES/STUDY DESIGN

A cohort of men age 65 and over diagnosed with prostate cancer between 1985 and the end of 1992 and followed through 1994. Subjects (n = 21,741) were ascertained by two population-based tumor registries covering the greater San Francisco-Oakland and Seattle-Puget Sound areas. Linkage of registry data with Medicare claims data and with HMO inpatient utilization data allowed the determination of health plan enrollment and the measurement of comorbid conditions. Multivariate regression models were used to examine HMO versus FFS treatment and survival differences adjusting for sociodemographic and clinical characteristics.

PRINCIPAL FINDINGS

Among cases with non-metastatic prostate cancer, HMO patients were more likely than FFS patients to receive aggressive therapy (either prostatectomy or radiation) in San Francisco-Oakland (odds ratio [OR] = 1.69, 95% CI = 1.46-1.96) but not in Seattle (OR = 1.15, 0.93-1.43). Among men receiving aggressive therapy, HMO cases were three to five times more likely to receive radiation therapy than prostatectomy. Overall mortality was equivalent over ten years (HMO versus FFS mortality risk ratio [RR] = 1.01, 0.94-1.08), but prostate cancer mortality was higher for HMO cases than for FFS cases (RR = 1.25, 1.13-1.39).

CONCLUSION

Despite marked treatment differences for clinically localized prostate cancer, overall ten-year survival for patients enrolled in two nonprofit group/staff HMOs was equivalent to survival among patients receiving care in the FFS setting, even after adjustment for sociodemographic and clinical characteristics. Similar overall but better prostate cancer-specific survival among FFS patients is most plausibly explained by differences between the HMO and FFS patients in both tumor characteristics and unmeasured patient selection factors.

Comparison of risk estimates for selected diseases and causes of death

BACKGROUND

Lifetime risk estimates of disease are limited by long-term data extrapolations and are less relevant to individuals who have already lived a period of time without the disease, but are approaching the age at which the disease risk becomes common. In contrast, short-term age-conditional risk estimates, such as the risk of developing a disease in the next 10 years among those alive and free of the disease at a given age, are less restricted by long-term extrapolation of current rates and can present patients with risk information tailored to their age. This study focuses on short-term age-conditional risk estimates for a broad set of important chronic diseases and nondisease causes of death among white and black men and women.

METHODS

The Feuer et al. (1993, Journal of the National Cancer Institute) [15] method was applied to data from a variety of sources to obtain risk estimates for select cancers, myocardial infarction, diabetes mellitus, multiple sclerosis, Alzheimer's, and death from motor vehicle accidents, homicide or legal intervention, and suicide.

RESULTS

Acute deaths from suicide, homicide or legal intervention, and fatal motor vehicle accidents dominate the risk picture for persons in their 20s, with only diabetes mellitus and end-stage renal disease therapy (for blacks only) having similar levels of risk in this age range. Late in life, cancer, acute myocardial infarction, Alzheimer's, and stroke become most common. The chronic diseases affecting the population later in life present the most likely diseases someone will face. Several interesting differences in disease and death risks were derived and reported among age-specific race and gender subgroups of the population.

CONCLUSION

Presentation of risk estimates for a broad set of chronic diseases and nondisease causes of death within short-term age ranges among population subgroups provides tailored information that may lead to better educated prevention, screening, and control behaviors and more efficient allocation of health resources.

The role of prostate-specific antigen (PSA) testing patterns in the recent prostate cancer incidence decline in the United States

OBJECTIVES

Trends in first-time and later PSA procedure rates are ascertained using longitudinal data from a population-based cohort. These trends are compared to trends in prostate cancer incidence to determine the role of PSA in the recent decline in prostate cancer incidence.

METHODS

Medicare data were linked with tumor registry data from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program. A 5 percent random sample (n = 39985) of Medicare beneficiaries from the SEER areas without a previous diagnosis of prostate cancer as of January 1, 1988 was followed through 1994. Trends in first-time PSA use were distinguished from those of second or later for men without diagnosed prostate cancer.

RESULTS

Trends in the rate of first-time PSA procedures track closely with trends in prostate cancer incidence rates, increasing until 1992 and decreasing thereafter. Similar patterns were observed by race and age group. Geographic variability in the dissemination of PSA screening was observed, yet the association between testing and incidence remained. Men in the cohort had a 4.7 percent chance of being diagnosed within three months of an initial PSA test, with the percentage falling for subsequent tests.

CONCLUSIONS

It is informative to distinguish first from later tests when assessing the effect of the diffusion of a test in a population. Taking this approach was useful in illuminating the role of PSA testing in a reversal of a long-term increase in prostate cancer incidence rates.

Conditional survival estimates in 34,963 patients with invasive carcinoma of the colon

PURPOSE

We report colon cancer survival rates that are conditioned on patients having already survived one or more years after diagnosis. These rates have more meaning clinically, because they consider those patients who have already survived a given period of time after treatment.

METHODS

The life table method was used to compute conditional survival rates, using population-based data obtained from the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute. Patients were diagnosed between 1983 and 1987 and followed up through 1994. Relative and observed survival rates are considered.

RESULTS

Survival rates up to ten years after diagnosis are reported by stage of disease, gender, and race for colon cancer patients who survived from one to five years after diagnosis. Survival rates are also reported by lymph node involvement.

CONCLUSIONS

Five-year and ten-year survival in colon cancer patients having already survived between one and five years after diagnosis continues to be influenced significantly by stage and race.

Estimating lifetime and age-conditional probabilities of developing cancer

Lifetime and age-conditional risk estimates of developing cancer provide a useful summary to the public of the current cancer risk and how this risk compares with earlier periods and among select subgroups of society. These reported estimates, commonly quoted in the popular press, have the potential to promote early detection efforts, to increase cancer awareness, and to serve as an aid in study planning. However, they can also be easily misunderstood and frightening to the general public. The Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute and the American Cancer Society have recently begun including in annual reports lifetime and age-conditional risk estimates of developing cancer. These risk estimates are based on incidence rates that reflect new cases of the cancer in a population free of the cancer. To compute these estimates involves a cancer prevalence adjustment that is computed cross-sectionally from current incidence and mortality data derived within a multiple decrement life table. This paper presents a detailed description of the methodology for deriving lifetime and age-conditional risk estimates of developing cancer. In addition, an extension is made which, using a triple decrement life table, adjusts for a surgical procedure that removes individuals from the risk of developing a given cancer. Two important results which provide insights into the basic methodology are included in the discussion. First, the lifetime risk estimate does not depend on the cancer prevalence adjustment, although this is not the case for age-conditional risk estimates. Second, the lifetime risk estimate is always smaller when it is corrected for a surgical procedure that takes people out of the risk pool to develop the cancer. The methodology is applied to corpus and uterus NOS cancers, with a correction made for hysterectomy prevalence. The interpretation and limitations of risk estimates are also discussed.

Breast cancer survival and treatment in health maintenance organization and fee-for-service settings

BACKGROUND

Enrollment in health maintenance organizations (HMOs) has increased rapidly during the past 10 years, reflecting a growing emphasis on health care cost containment. To determine whether there is a difference in the treatment and outcome for female patients with breast cancer enrolled in HMOs versus a fee-for-service setting, we compared the 10-year survival and initial treatment of patients with breast cancer enrolled in both types of plans.

METHODS

With the use of tumor registries covering the greater San Francisco-Oakland and Seattle-Puget Sound areas, respectively, we obtained information on the treatment and outcome for 13,358 female patients with breast cancer, aged 65 years and older, diagnosed between 1985 and 1992. We linked registry information with Medicare data and data from the two large HMOs included in the study. We compared the survival and treatment differences between HMO and fee-for-service care after adjusting for tumor stage, comorbidity, and sociodemographic characteristics.

RESULTS

In San Francisco-Oakland, the 10-year adjusted risk ratio for breast cancer deaths among HMO patients compared with fee-for-service patients was 0.71 (95% confidence interval [CI] = 0.59-0.87) and was comparable for all deaths. In Seattle-Puget Sound, the risk ratio for breast cancer deaths was 1.01 (95% CI = 0.77-1.33) but somewhat lower for all deaths. Women enrolled in HMOs were more likely to receive breast-conserving surgery than women in fee-for-service (odds ratio = 1.55 in San Francisco-Oakland; 3.39 in Seattle). HMO enrollees undergoing breast-conserving surgery were also more likely to receive adjuvant radiotherapy (San Francisco-Oakland odds ratio = 2.49; Seattle odds ratio = 4.62).

CONCLUSIONS

Long-term survival outcomes in the two prepaid group practice HMOs in this study were at least equal to, and possibly better than, outcomes in the fee-for-service system. In addition, the use of recommended therapy for early stage breast cancer was more frequent in the two HMOs.

The lifetime risk of developing prostate cancer in white and black men

Two factors help explain increases in the lifetime risk of developing cancer: (a) decreasing overall mortality rates such that people are now living to older ages when cancer rates rise rapidly; and (b) increasing numbers of cancer cases discovered by new medical procedures, screening tests, and changes in the population risk factors. Prostate cancer lifetime risk estimates are particularly influenced by improved mortality rates and increased detection of asymptomatic disease. In this study, we report trends in lifetime risk estimates of developing prostate cancer in white and black men in the United States, from 1975 to 1993, and focus on the effects of changing mortality and screening. For the study period 1975-1977 to 1991-1993, the lifetime risk of developing invasive prostate cancer increased from 7.3 to 19.6% for whites and from 8.5 to 18.6% for blacks. When we recalculated these estimates using age-specific incidence trends from 1975 through 1989 (thereby controlling for the effect of prostate-specific antigen serum testing on prostate cancer incidence rates), the lifetime risk estimates in 1991-1993 fell to 13.8% for whites and 12.5% for blacks. When we made an additional assumption, basing lifetime risk estimates on higher 1975-1977 mortality rates, the lifetime risk estimates in 1991-1993 became 11.3% for whites and 11.8% for blacks. It is also shown that although mortality rates have improved for white and black men over the study period, they are much larger for blacks than whites in younger age groups, when the prevalence of prostate cancer is relatively low. As a result, fewer blacks survive to older ages when age-specific prostate cancer rates are large. It is of note that blacks have higher incidence rates for prostate cancer than do whites at every age-specific interval. Hence, increasing trends in lifetime risk of prostate cancer suggest, in large part, longer life expectancy and better detection methods.

Prostate cancer incidence and mortality rates among white and black men

This paper presents prostate cancer incidence and mortality rates in the United States by factors associated with the disease at diagnosis and explores racial differences in these rates. The analysis is based on population-based cancer data from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute. Incidence rates increased sharply from 1973 to 1992 (more so among whites), with the increase attributed to screening and preferential finding of low-risk, slow-growing tumors (that is, length bias). Mortality rates increased slightly (more so among blacks). The 1988-1992 white and black prostate cancer mortality rates comprise cases diagnosed as early as 1973. These rates remained fairly constant for each stage category at diagnosis, except for black men diagnosed with localized or unstaged disease, in whom the rates increased. Of the white prostate cancer cases, 33% are diagnosed with localized disease, 16% are diagnosed with regional disease, and 38% are diagnosed with distant disease. The corresponding percentage for black patients are 31, 12, and 45%. Prostate cancer mortality rates for blacks diagnosed with localized, regional, distant, and unstaged disease are 1.9, 1.5, 2.4, and 2.0 times those of whites. The time from diagnosis to death depends on the stage and age at diagnosis, with the time somewhat longer for whites than blacks. This longer time period is due, in part, to better staging and length bias. The effect of therapy on prostate cancer mortality rates is unclear.

Risk-adjusted cancer-incidence rates (United States)

A risk-adjusted method is proposed for estimating cancer incidence rates from data collected by the Surveillance, Epidemiology, and End Results (SEER) program of the US National Cancer Institute. Unlike the conventional incidence-rate estimates reported by SEER, this method considers only the first primary cancer, and adjusts for population-based cancer prevalence, as well as for surgical procedures which remove an individual from risk of developing a given cancer. Thus, risk-adjusted incidence-rates more accurately reflect the average cancer risk for individuals in the cancer-free, at-risk population. The results of the analysis indicate that, in general, incidence-rate estimates are fairly similar between the conventional and risk-adjusted methods. However, this is not the case for certain cancer sites which may have: (i) a high number of subsequent primary cancers (e.g., melanomas-skin); (ii) a high cancer prevalence proportion (e.g., prostate cancer); (iii) a high number of subsequent primary cancers and prevalence proportion (e.g., female breast); or (iv) a high prevalence of removal of the organ in question (e.g., cervical and uterine cancers). For example, by applying the risk-adjusted incidence method for in situ and invasive cervical cancer, we found that in the period 1990-92 the age-adjusted incidence-rate estimate increased from 57.8 to 66.3 (15 percent) per 100,000 person-years; the greatest increase in the incidence-rate estimate occurred for women aged 65 to 69 years, from 40.1 to 63.2 (58 percent) per 100,000 person-years; and the lifetime risk of developing cervical cancer increased from 4.6 (1 in 22) to 5.5 (1 in 18) percent.

Cephalometric assessment of sagittal relationship between maxilla and mandible

This investigation was undertaken to evaluate if palatal plane could be used as a skeletal plane of reference in lateral cephalometric radiographs to evaluate sagittal maxillomandibular relationship. Various cephalometric landmarks in the maxilla and the mandible were projected to the palatal plane, and the linear distances between them were measured. In this three-part study, the first part evaluated changes in the inclination of palatal plane and in the linear distances from the age of 6 to 24 years in longitudinal records of 86 patients (46 male, 40 female). The second part established acceptable adult norms by evaluating 111 white dental students (89 men, 22 women) with Class I molar relationships, no history of orthodontic treatment, and good facial balance. The third part evaluated the proposed measures in pretreatment radiographs of 445 patients (171 men, 274 women) with a variety of malocclusions to compare the results of various diagnostic criteria for assessment of sagittal jaw relationships. The first part indicated the inclination of the palatal plane was stable throughout the growth period studied. The distance between projections from points A and B on the palatal plane (App-Bpp) was found to be the best indicator of sagittal jaw relationship. This was the least variable of the four measures considered in part two of the study. When compared with the angle ANB, the Wits appraisal and measurement of landmarks to a perpendicular from nasion in 50 patients, it was a more reliable diagnostic criterion than the other measures. Among the patients whose malocclusions were incorrectly diagnosed. Wits appraisal was consistently biased in the Class III direction. The methods using the ANB angle and the nasion perpendicular plane did not indicate any definitive trend.