Colorectal cancer incidence in the United States, 1999‐2004

BACKGROUND:

By using recent national cancer surveillance data, the authors investigated colorectal cancer (CRC) incidence by subpopulation to inform the discussion of demographic‐based CRC guidelines.

METHODS:

Data included CRC incidence (1999‐2004) from the combined National Program of Cancer Registries and Surveillance, Epidemiology, and End Results Program databases. Incidence rates (age‐specific and age‐adjusted to the 2000 US standard population) were reported among individuals ages 40 to 44 years, 45 to 49 years, 50 to 64 years, and ≥65 years by sex, subsite, disease stage, race, and ethnicity. Rate ratios (RR) and rate differences (RD) were calculated to compare CRC rates in different subpopulations.

RESULTS:

Incidence rates were greater among men compared with women and among blacks compared with whites and other races. Incidence rates among Asians/Pacific Islanders (APIs), American Indians/Alaska Natives (AI/ANs), and Hispanics consistently were lower than among whites and non‐Hispanics. Sex disparities were greatest in the population aged ≥65 years, whereas racial disparities were more pronounced in the population aged <65 years. Although the RD between blacks and whites diminished at older ages, the RD between APIs and whites, between AI/ANs and whites, and between non‐Hispanics and Hispanics increased with increasing age. By subsite, blacks had the highest incidence rates compared with whites and other races in the proximal and distal colon; the reverse was true in the rectum. By stage, whites had higher incidence rates than blacks and other races for localized and regional disease; for distant and unstaged disease, blacks had higher incidence rates than whites.

CONCLUSIONS:

The current findings suggested differences that can be considered in formulating targeted screening and other public health strategies to reduce disparities in CRC incidence in the United States. Cancer 2009. Published 2009 by the American Cancer Society.     

Reconstructing PSA testing patterns between black and white men in the US from Medicare claims and the National Health Interview Survey

BACKGROUND: Frequencies of prostate-specific antigen (PSA) test administration were not actively monitored on a national level during the first decade of PSA testing. The objectives of this article were to reconstruct patterns of PSA testing between black and white men in the US and to determine the extent of any racial disparity in PSA use. METHODS: Data from the 2000 National Health Interview Survey were used to model the adoption of PSA and to estimate the distribution of age at first test. Longitudinal Medicare claims data were used to estimate the distribution of intervals between tests. The rates of initial and subsequent tests were then combined by simulation to reconstruct individual screening histories. Results are from the reconstructed model. RESULTS: Overall, 45% of white men and 43% of black men within ages 40-84 years had at least 1 PSA test by the year 2000. The authors found that among older men, whites adopted PSA screening earlier than blacks, whereas among younger men, this trend was reversed, with blacks adopting screening earlier than whites. Annual testing frequencies generated by the simulation model were higher for white men aged>or=60 years and higher for black men aged<60 years. CONCLUSIONS: Findings indicated fairly similar patterns overall of PSA testing for blacks and whites. These similarities indicated that racial disparity in PSA testing is probably not a major factor behind current racial differences in prostate cancer mortality rates and declines. Knowledge of patterns of screening is important to an understanding of the impact of population screening on cancer incidence and mortality, but retrospective data sources have significant limitations when used to estimate these patterns of care.     

Geographic variation of racial/ethnic disparities in colorectal cancer testing among medicare enrollees

BACKGROUND:

The Medicare population has documented racial/ethnic disparities in colorectal cancer (CRC) screening, but it is unknown whether these disparities differ across geographic regions.

METHODS:

Among Medicare enrollees within 8 US states, we ascertained up‐to‐date CRC screening on December 31, 2003 (fecal occult blood testing in the prior year or sigmoidoscopy or colonoscopy in the prior 5 years). Logistic regression models tested for regional variation in up‐to‐date status among white versus different nonwhite populations (blacks, Asian/Pacific Islanders [APIs], Hispanics). We estimated regression‐adjusted region‐specific prevalence of up‐to‐date status by race/ethnicity and compared adjusted white versus nonwhite up‐to‐date prevalence across regions by using generalized least squares regression.

RESULTS:

White versus nonwhite up‐to‐date status varied significantly across regions for blacks (P = .01) and APIs (P < .001) but not Hispanics (P = .62). Whereas the white versus black differences in proportion up‐to‐date were greatest in Atlanta (Georgia), rural Georgia, and the San Francisco Bay Area of California (range, 10%‐16% differences, blacksP < .001). White versus Hispanic differences were substantial but homogeneous across regions (range, 8%‐16% differences, Hispanics CONCLUSIONS: Significant geographic variation in up‐to‐date status among black and API Medicare enrollees is associated with heterogeneous racial/ethnic disparities for these groups across US regions. Cancer 2011. © 2011 American Cancer Society.     

Incidence of colorectal carcinoma in the U.S.: an update of trends by gender, race, age, subsite, and stage, 1975-1994

BACKGROUND: Colon carcinoma incidence rates have risen sharply over the second half of this century, particularly among males and blacks. In the late 1970s, incidence rates among whites began to decline for distant disease. Approximately 10 years later regional disease rates began to fall. The decline in incidence rates among whites largely has been attributed to more widespread colorectal carcinoma screening. However, similar trends by stage in blacks have not been observed. METHODS: The incidence of colorectal carcinoma was evaluated by race, gender, age, and stage of disease for each subsite using data from > 220,000 cases diagnosed between 1975 and 1994 in the U. S. Surveillance, Epidemiology, and End Results program. RESULTS: Recent data have continued to show a decrease in incidence rates of total colorectal carcinoma in whites since the mid-1980s, particularly for the distal colon and rectum. Overall, proximal colon carcinoma rates were higher than distal colon or rectal carcinoma rates throughout the study period. Proximal colon carcinoma rates in blacks were considerably higher than in whites and continued to increase, whereas rates in whites showed signs of declining. The age-specific and stage-specific trends for proximal colon carcinoma in blacks were not consistent with the possibility of earlier disease detection through screening. CONCLUSIONS: Etiologic studies are necessary to understand the large increases in the incidence of proximal colon carcinoma among blacks.     

Association of area sociodemographic characteristics and capacity for treatment with disparities in colorectal cancer care and mortality

BACKGROUND:

Disparities in treatment and mortality for colorectal cancer (CRC) may reflect differences in access to specialized care or other characteristics of the area where an individual lives.

METHODS:

Surveillance, Epidemiology and End Results Program–Medicare data for seniors diagnosed with CRC were linked to area measures of the sociodemographic characteristics and the capacity of surgeons, medical oncologists, and radiation oncologists. Outcomes included receipt of stage‐appropriate CRC care and mortality.

RESULTS:

After adjustment, blacks and Hispanics were less likely than whites to undergo surgery (odds ratio [OR] 0.57, 95% confidence interval (CI) 0.52‐0.63 and OR 0.82, 95% CI 0.70‐0.95, respectively). Individuals who lived in areas with the highest tertile of surgeon capacity were more likely to undergo resection than those in the lowest, and use of surgery declined as the percentage of blacks in the area increased. Adjustment for the area measures resulted in a modest decline in disparities in care relative to whites (5.3% for black). Blacks also experienced greater all‐cause and cancer‐specific mortality than whites. Further adjustment for area sociodemographics and surgeon capacity reduced the disparity in mortality between blacks and whites. Although there was a similar black/white disparity in the use of adjuvant chemotherapy, the disparity remained after adjustment for area characteristics, although use of chemotherapy was greater in areas with the greatest capacity of medical oncologists.

CONCLUSIONS:

Sociodemographic characteristics and measures of the availability of specialized cancer providers in the area in which an individual resides modestly mediated disparities in the receipt of CRC care and mortality, suggesting that other factors may also be important. Cancer 2011;. © 2011 American Cancer Society.     

Surveillance after resection for colorectal cancer

BACKGROUND:

Professional societies recommend posttreatment surveillance for colorectal cancer (CRC) survivors. This study describes the use of surveillance over time, with a particular focus on racial/ethnic disparities, and also examines the role of area characteristics, such as capacity for CRC screening, on surveillance.

METHODS:

Surveillance, Epidemiology, and End Results (SEER)‐Medicare data were used to identify individuals aged 66 to 85 years who were diagnosed with CRC from 1993 to 2005 and treated with surgery. The study examined factors associated with subsequent receipt of a colonoscopy, carcinoembryonic antigen (CEA) testing, primary care (PC) visits, and a composite measure of overall surveillance.

RESULTS:

Of eligible subjects, 61.0% had a colonoscopy, 68.0% had CEA testing, 77.1% had PC visits, and 43.0% received overall surveillance. After adjustment, blacks were less likely than whites to undergo colonoscopy (odds ratio [OR] 0.76, 95% confidence interval [CI] = 0.69‐0.83) and to receive CEA testing and overall surveillance, whereas white/Hispanic rates did not differ. Rates for all outcomes increased from 1993 to 2005, but black/white disparities remained. Individuals in areas with greatest capacity for CRC screening were more likely (OR = 1.09, 95% CI = 1.02‐1.18) to receive colonoscopy, and those in areas with the greatest percentage of blacks were less likely (OR = 0.89, 95% CI = 0.83‐0.95) to receive colonoscopy. Those living in areas with shortage of PC were less likely to receive PC visits (OR = 0.55, 95% CI = 0.48‐0.64) and overall surveillance (OR = 0.83, 95% CI = 0.71‐0.98).

CONCLUSIONS:

Many CRC survivors do not get recommended surveillance, and black/white disparities in rates of surveillance have not improved. Characteristics of the area where an individual lives contribute to the use of surveillance. Cancer 2013. © 2012 American Cancer Society.     

Recent trends in cervix uteri cancer

Since the prevalence of several risk factors for cervix uteri cancer, such as sexual activity patterns, cigarette smoking, and contraceptive use, has changed over time, the authors analyzed US trends for this cancer during the 1970s to 1980s to search for corresponding variations. Invasive cervical cancer incidence and mortality rates continued to decrease among blacks and whites, although declines are moderating or plateauing among young whites. Carcinoma in situ rates have not changed greatly or have declined, more so among blacks than whites. Excess risks among blacks are less evident among younger than older age groups. Increasing trends were seen only among whites in certain age groups or with certain histologic types. Declining trends in cervical cancer appear related to the widespread use of cervical cytologic screening programs, which have counteracted increases anticipated from changes in risk factor prevalence. Continued surveillance is warranted, however, with special attention to the trends in cervical adenocarcinoma.     

Racial differences in colorectal cancer screening practices and knowledge within a low-income population

BACKGROUND: Although colorectal cancer (CRC) is the third leading cause of cancer death among US women and is particularly deadly among African Americans, CRC screening rates remain low. Within a low-income population of women, the authors examined racial differences in practices, knowledge, and barriers related to CRC screening. METHODS: Face-to-face interviews were conducted with 941 women (white, n= 186; African American, n= 755) older than age 50 years who were living in subsidized housing communities in 11 cities in North and South Carolina. Women were asked questions about their CRC screening history and their knowledge and beliefs concerning CRC screening. RESULTS: Half (49%) of the women interviewed were within CRC screening guidelines, and this did not vary by race (P= .17). However, African American women were half as likely as white women to report having had a screening colonoscopy within the past 10 years (odds ratio [OR], 0.46; P< .001). Awareness of tests for CRC was low overall (39%) and was lower among African Americans than whites (OR, 0.44; P< .001). Compared with white women, African American women were less likely to report embarrassment as a barrier (OR, 0.59; P= .008) and more likely to report lack of insurance coverage (OR, 1.75; P= .098). CONCLUSIONS: Efforts must continue to increase women's knowledge of both CRC screening tests and colon cancer risk factors. Among these low-income women, routine encounters with the healthcare system may present opportunities to reduce deficits in CRC knowledge and to improve overall CRC screening rates.     

Colorectal Cancer in the Arab World - Screening Practices and Future Prospects

Colorectal cancer (CRC) incidence and mortality rates have dropped 30% in the US in the last 10 years among adults ages 50 and older due to the widespread uptake of colonoscopy, yet incidences in the Arab countries have been increasing in the past ten years, albeit with lower figures when compared with developed countries. Lifestyle changes, food consumption patterns and obesity have been observed during the past years where the regular consumption of traditional foods is being replaced with more Western-style and ready-made foods. Most high income countries have implemented population based colorectal cancer screening programs, which aid in decreasing the incidence and mortality of cancer, while these are lacking in most of the Arab world countries due to many cultural and religious barriers to CRC screening as well as lack of high education or familiarity. What is needed is health education to modify risky lifestyle, and to increase motives and enhance positive attitudes towards early screening especially amongst high risk groups in addition to policy designed to encourage healthierliving.     

Gender differences in colorectal cancer: implications for age at initiation of screening

There is some variation regarding age at initiation of screening for colorectal cancer (CRC) between countries, but the same age of initiation is generally recommended for women and men within countries, despite important gender differences in the epidemiology of CRC. We have explored whether, and to what extent, these differences would be relevant regarding age at initiation of CRC screening. Using population-based cancer registry data from the US and national mortality statistics from different countries, we looked at cumulative 10-year incidence and mortality of CRC reached among men at ages 50, 55, and 60, and found that women mainly reached equivalent levels when 4 to 8 years older. The gender differences were remarkably constant across populations and over time. These patterns suggest that gender differentiation of age at initiation may be worthwhile to utilise CRC-screening resources more efficiently.     

The annual report to the nation on the status of cancer, 1973-1997, with a special section on colorectal cancer

BACKGROUND: This annual report to the nation addresses progress in cancer prevention and control in the U.S. with a special section on colorectal cancer. This report is the joint effort of the American Cancer Society, the National Cancer Institute (NCI), the North American Association of Central Cancer Registries (NAACCR), and the Centers for Disease Control and Prevention (CDC), including the National Center for Health Statistics (NCHS). METHODS: Age-adjusted rates were based on cancer incidence data from the NCI and NAACCR and underlying cause of death as compiled by NCHS. Joinpoint analysis was based on NCI Surveillance, Epidemiology, and End Results (SEER) program incidence rates and NCHS death rates for 1973-1997. The prevalence of screening examinations for colorectal cancer was obtained from the CDC's Behavioral Risk Factor Surveillance System and the NCHS's National Health Interview Survey. RESULTS: Between 1990-1997, overall cancer incidence and death rates declined. Joinpoint analyses of cancer incidence and death rates confirmed the declines described in earlier reports. The incidence trends for colorectal cancer have shown recent steep declines for whites in contrast to a leveling off of the rates for blacks. State-to-state variations occurred in colorectal cancer screening prevalence as well as incidence and death rates. CONCLUSIONS: The continuing declines in overall cancer incidence and death rates are encouraging. However, a few of the top ten incidence or mortality cancer sites continued to increase or remained level. For many cancer sites, whites had lower incidence and mortality rates than blacks but higher rates than Hispanics, Asian and Pacific Islanders, and American Indians/Alaska Natives. The variations in colorectal cancer incidence and death rates by race/ethnicity, gender, age, and geographic area may be related to differences in risk factors, demographic characteristics, screening, and medical practice. New efforts currently are underway to increase awareness of screening benefits and treatment for colorectal cancer.     

Evaluation of recent trends in cancer mortality and incidence among blacks

Recent trends in the cancer incidence, mortality, and 5-year survival rate for the black population were evaluated using the available national data up to 1981. Blacks have the highest overall age-adjusted cancer rates in both incidence and mortality of any US population group. The overall cancer incidence rates for blacks rose 17%, while for whites it increased 13% from 1969 to 1981. The rate in black men has increased 22.9%, while the rate in black women has increased 13.1%. The overall increase is the result of increases in cancers of the lung, prostate, colon-rectum, and esophagus. The age-specific incidence of lung cancer reflects the decrease of its incidence in those between 20 and 40 years of age because of the change in smoking habits after the Surgeon General's report on smoking. The overall cancer mortality rates for blacks increased 39% during the period. Lung cancer had the highest mortality rate, having increased more than 77.8% since 1969. This trend greatly reflects the recent increase in lung cancer incidence among black women. The overall 5-year cancer survival pattern for blacks was almost unchanged from 1973 to 1981, while whites had slightly higher survival rates during this period. However, blacks had substantial increases in survival rates for cancers of the esophagus and bladder during the period.     

A trial of 3 interventions to promote colorectal cancer screening in African Americans

BACKGROUND:

Colorectal cancer (CRC) is the second leading cause of cancer death in the United States. CRC incidence and mortality rates are higher among blacks than among whites, and screening rates are lower in blacks than in whites. For the current study, the authors tested 3 interventions that were intended to increase the rate of CRC screening among African Americans.

METHODS:

The following interventions were chosen to address evidence gaps in the Centers for Disease Control and Prevention's Guide to Community Preventive Services: one‐on‐one education, group education, and reducing out‐of‐pocket costs. Three hundred sixty‐nine African‐American men and women aged ≥50 years were enrolled in this randomized, controlled community intervention trial. The main outcome measures were postintervention increase in CRC knowledge and obtaining a screening test within 6 months.

RESULTS:

There was substantial attrition: Two hundred fifty‐seven participants completed the intervention and were available for follow‐up 3 months to 6 months later. Among completers, there were significant increases in knowledge in both educational cohorts but in neither of the other 2 cohorts. By the 6‐month follow‐up, 17.7% (11 of 62 participants) of the Control cohort reported having undergone screening compared with 33.9% (22 of 65 participants) of the Group Education cohort (P = .039). Screening rate increases in the other 2 cohorts were not statistically significant.

CONCLUSIONS:

The current results indicated that group education could increase CRC cancer screening rates among African Americans. The screening rate of <35% in a group of individuals who participated in an educational program through multiple sessions over a period of several weeks indicated that there still are barriers to overcome. Cancer 2010. © 2010 American Cancer Society.     

Racial disparities in colorectal cancer survival

BACKGROUND:

Racial/ethnic differences in colorectal cancer (CRC) survival have been documented throughout the literature. However, the reasons for these disparities are difficult to decipher. The objective of this analysis was to determine the extent to which racial/ethnic disparities in survival are explained by differences in sociodemographics, tumor characteristics, diagnosis, treatment, and hospital characteristics.

METHODS:

A cohort of 37,769 Medicare beneficiaries who were diagnosed with American Joint Committee on Cancer stages I, II, and III CRC from 1992 to 2002 and resided in 16 Surveillance, Epidemiology, and End Results (SEER) regions of the United States was identified in the SEER‐Medicare linked database. Survival was estimated using the Kaplan‐Meier method. Cox proportional hazards modeling was used to estimate hazard ratios (HRs) of mortality and 95% confidence intervals (CIs).

RESULTS:

Black patients had worse CRC‐specific survival than white patients, but the difference was reduced after adjustment (adjusted HR [aHR], 1.24; 95% CI, 1.14‐1.35). Asian patients had better survival than white patients after adjusting for covariates (aHR, 0.80; 95% CI, 0.70‐0.92) for stages I, II, and III CRC. Relative to Asians, blacks and whites had worse survival after adjustment (blacks: aHR, 1.56; 95% CI, 1.33‐1.82; whites: aHR, 1.26; 95% CI, 1.10‐1.44). Comorbidities and socioeconomic Status were associated with a reduction in the mortality difference between blacks and whites and blacks and Asians.

CONCLUSIONS:

Comorbidities and SES appeared to be more important factors contributing to poorer survival among black patients relative to white and Asian patients. However, racial/ethnic differences in CRC survival were not fully explained by differences in several factors. Future research should further examine the role of quality of care and the benefits of treatment and post‐treatment surveillance in survival disparities. Cancer 2010. © 2010 American Cancer Society.     

Cancer mortality in a higher-income black population in New York State. Comparison with rates in the United States as a whole

In the 1980 Census the median family income among blacks in Suffolk County, New York (i.e., $19,604) was much higher than that for American blacks as a whole (i.e., $12,618) and 94.1% of that for American whites (i.e., $20,840), but the proportion below the poverty level was still higher for Suffolk County blacks than for American whites. Observed numbers of deaths from 1979 to 1985 for total cancers and most cancer sites in Suffolk County black men and women were not lower than expected on the basis of age-specific and gender-specific death rates for blacks in the US. Although numbers of deaths from cervical cancer and prostate cancer were slightly lower than expected in Suffolk County blacks versus American blacks, these numbers were still significantly greater than expected on the basis of death rates among American whites. Age-specific death rates for age groups 25 to 44 years to 55 to 64 years tended to be lower in Suffolk County for lung cancers in black men but not for breast cancer in black women. Specific cancer sites, which differ in the direction of the association between incidence and socioeconomic status, age, and gender must be considered in comparisons of cancer mortality by race and socioeconomic level. Implications of the comparisons were discussed with regard to the goal of reducing racial differences in cancer death rates.     

Incidence of esophageal and gastric cancers among Hispanics,non-Hispanic whites and non-Hispanic blacks in the United States: subsite and histology differences

Objective We examined subsite- and histology-specific esophageal and gastric cancer incidence patterns among Hispanics/Latinos and compared them with non-Hispanic whites and non-Hispanic blacks. Methods Data on newly diagnosed esophageal and gastric cancers for 1998–2002 were obtained from 37 population-based central cancer registries, representing 66% of the Hispanic population in the United States. Age-adjusted incidence rates (2000 US) were computed by race/ethnicity, sex, anatomic subsite, and histology. The differences in incidence rates between Hispanics and non-Hispanics were examined using the two-tailed z-statistic. Results Squamous cell carcinoma accounted for 50% and 57% of esophageal cancers among Hispanic men and women, respectively, while adenocarcinoma accounted for 43% among Hispanic men and 35% among Hispanic women. The incidence rate of squamous cell carcinoma was 48% higher among Hispanic men (2.94 per 100,000) than non-Hispanic white men (1.99 per 100,000) but about 70% lower among Hispanics than non-Hispanic blacks, for both men and women. In contrast, the incidence rates of esophageal adenocarcinoma were lower among Hispanics than non-Hispanic whites (58% lower for men and 33% for women) but higher than non-Hispanic blacks (70% higher for men and 64% for women). Cardia adenocarcinoma accounted for 10–15% of gastric cancers among Hispanics, and the incidence rate among Hispanic men (2.42 per 100,000) was 33% lower than the rate of non-Hispanic white men (3.62 per 100,000) but 37% higher than that of non-Hispanic black men. The rate among Hispanic women (0.86 per 100,000), however, was 20% higher than that of non-Hispanic white women (0.72 per 100,000) and 51% higher than for non-Hispanic black women. Gastric non-cardia cancer accounted for approximately 50% of gastric cancers among Hispanics (8.32 per 100,000 for men and 4.90 per 100,000 for women), and the rates were almost two times higher than for non-Hispanic whites (2.95 per 100,000 for men and 1.72 per 100,000 for women) but about the same as the non-Hispanic blacks. Conclusion Subsite- and histology-specific incidence rates of esophageal and gastric cancers among Hispanics/Latinos differ from non-Hispanics. The incidence rates of gastric non-cardia cancer are almost two times higher among Hispanics than non-Hispanic whites, both men and women. The rates of gastric cardia cancer are lower among Hispanics than non-Hispanic whites for men but higher for women. The rates of esophageal and gastric cardia adenocarcinomas are higher among Hispanics than non-Hispanic blacks.     

Plantar melanoma: Is the incidence of melanoma of the sole of the foot really higher in blacks than whites?

The overall incidence of malignant melanoma in black populations is considerably lower than that in whites. There have been repeated suggestions in the literature that black persons may have an increased incidence of melanoma of the sole, relative to whites, because among blacks with melanoma there is a high proportion with tumors of the sole of the foot. Whether this observed difference in site distribution represents a difference in incidence rates has never been demonstrated. Data on cancer incidence from 2 areas, western Washington State (1974-1983) and metropolitan Atlanta (1975-1984), were analyzed to examine this question. The annual area- and age-adjusted incidence of plantar melanoma was 1.7 per million per year for blacks and 2.0 per million per year for whites (relative risk for blacks as compared with whites = 0.88, 95% confidence interval = 0.36-2.11). These data argue that in North America there is little difference between blacks and whites in the incidence of plantar melanoma, and that the well known proportional difference appears to be due instead to the decreased incidence in blacks of melanoma on skin surfaces other than the soles of the feet.     

Increasing colorectal cancer incidence rates in Japan

We examined trends of colorectal cancer incidence rates among Japanese (Miyagi Prefecture) and United States (US) whites (State of Connecticut) between 1959 and 1992. Age-standardized rates in Japan have increased dramatically and are now similar to US white rates. For both colon and rectum, age-specific rates in Japanese men born after 1930 exceed those in US whites, and the Japanese excess increases with year of birth. Similar patterns are evident for women. The current trends suggest that colorectal cancer will become a major source of morbidity and mortality in Japan, as these young Japanese age and their risks increase.     

Carcinoma in situ of the colorectum: SEER trends by race, gender, and total colorectal cancer.

BACKGROUND AND OBJECTIVES: To determine if Americans of African origin (blacks) have less access to colonoscopic polypectomy than Americans of European origin (whites), the rate of carcinoma in situ of the colorectum (CIS), a disease more similar to benign adenoma of the colorectum than invasive cancer in its symptomatology, discovery, and treatment, was determined in the United States from 1973 to 1994. The hypothesis being tested is that CIS will be far less common in blacks than in whites and that rates of CIS should be increasing in whites from 1973 to 1994. METHODS: CIS and invasive carcinoma of the colorectum incidence data were obtained from Surveillance, Epidemiology, and End Results (SEER) Public Use Files from 1973 through 1994. Rates were age adjusted and proportions determined by division of CIS rates for each subsite by total carcinoma rates, for each year, race, and gender. The colorectum was divided anatomically in this analysis at the junction of the descending and sigmoid colon. RESULTS: The relationships between male/female and black/white CIS incidence rates were broadly similar to invasive cancer rates over the 21 years of SEER, demonstrating a white male predominance for distal disease, a black male predominance for proximal disease, and a decline in incidence since 1988. CIS as a proportion of total colorectal cancer increased in all races and genders from 1973 to 1987, but then declined in all groups. CONCLUSIONS: The majority of CIS is excised by endoscopic resection. Therefore, this might be considered a surrogate population for those individuals who have colonoscopic resection of benign adenomas. It is this latter treatment that has been hypothesized to be the cause for the declining incidence of invasive colorectal cancer. However, data presented herein do not support this hypothesis.