Use of colonoscopy for colorectal cancer screening: evidence from the 2000 National Health Interview Survey

Screening for colon cancer

Colorectal cancer screening reduces mortality in individuals 50 years and older. Each of the screening tests currently available has advantages and limitations, and there is no consensus as to which test or combination of tests is best. What is clear, however, is that the rates of colorectal cancer screening remain low. This review summarizes the clinical evidence supporting colorectal cancer screening in the average risk population and in high risk groups, discusses the advantages and disadvantages of the available screening tests, outlines the currently recommended guidelines for screening based on risk category, and discusses new and emerging technologies for colorectal cancer screening.

Associations of subsite-specific colorectal cancer incidence rates and stage of disease at diagnosis with county-level poverty, by race and sex

BACKGROUND

This study examined associations of subsite-specific colorectal cancer incidence rates and stage of the disease with county-level poverty.

METHODS

The 1998-2001 colorectal cancer incidence data, covering 75% of the United States population, were from 38 states and metropolitan areas. The county-level poverty data were categorized into 3 groups according to the percentage of the population below the poverty level in 1999: <10% (low-poverty), 10%-19% (middle-poverty), and >or=20% (high-poverty). Age-adjusted subsite-specific incidence rates (for all ages) and stage-specific incidence rates (for ages >or=50) were examined by race (whites and blacks), sex, and the county's poverty level. The differences in the incidence rates were examined using the 2-tailed z-statistic.

RESULTS

The incidence rates of proximal colon cancer were higher among white males (11% higher) and white females (15% higher) in the low-poverty than in the high-poverty counties. No differences across county poverty levels were observed among whites for distal colon and rectal cancers or among blacks for all the subsites. The late-to-early stage incidence rate ratios were higher in the high-poverty than in the low-poverty counties among white and black males for distal colon and rectal cancers, among white females for distal colon cancer, and among black females for rectal cancer. For proximal colon cancer, however, the late-to-early stage rate ratios were similar across all county poverty levels.

CONCLUSIONS

Higher incidence rates of proximal cancer were observed among white males and females in the low-poverty counties relative to the high-poverty counties. The higher late-to-early stage rate ratios in high-poverty than in low-poverty counties is observed for distal colon and rectal cancers, but not for proximal colon cancer.

Colorectal cancer screening: health impact and cost effectiveness

BACKGROUND

Colorectal cancer is the second leading cause of cancer-related death in the United States, yet recommended screenings are not delivered to most people. This assessment of colorectal cancer screening's value to the U.S. population is part of the update to a 2001 ranking of recommended clinical preventive services found in the accompanying article. This article describes the burden of disease prevented and cost-effectiveness as a result of offering patients a choice of colorectal cancer screening tools.

METHODS

Methods used were designed to ensure consistent estimates across many services and are described in more detail in the companion articles. In a secondary analysis, the authors also estimated the impact of increasing offers for colorectal cancer screening above current levels among the current cross-section of adults aged 50 and older.

RESULTS

If a birth cohort of 4 million were offered screening at recommended intervals, 31,500 deaths would be prevented and 338,000 years of life would be gained over the lifetime of the birth cohort. In the current cross-section of people aged 50 and older, 18,800 deaths could be prevented each year by offering all people in this group screening at recommended intervals. Only 58% of these deaths are currently being prevented. In year 2000 dollars, the cost effectiveness of offering patients aged 50 and older a choice of colorectal cancer screening options is $11,900 per year of life gained.

CONCLUSIONS

Colorectal cancer screening is a high-impact, cost-effective service used by less than half of persons aged 50 and older.

Body mass index and use of mammography screening in the United States

BACKGROUND

Obese and underweight women may be less likely to seek cancer screening because of health status, self-perception, and body image related to non-desirable weight. This study examined the relationship between body mass index (BMI) and mammography screening, using the data from the year 2000 United States National Health Interview Survey.

METHODS

This study included 7692 white and 1496 black female participants aged 40-80, who were randomly selected. Body mass index (kg/m2), based on self-reported weight and height, was compared between women with and without a mammogram in the past 2 years using logistic regression.

RESULTS

Compared to women with normal body mass index, underweight and extremely obese women were more likely to have no screening mammograms in the past 2 years (odds ratio (OR) = 1.8, 95% confidence interval (CI), 1.2-2.6 for underweight women; odds ratio = 1.3, 95% confidence interval, 1.0-1.8 for extremely obese women). When data were analyzed by race, the odds ratio estimates were 1.8 for underweight white women (95% confidence interval, 1.3-2.7) and 1.4 for extremely obese white women (95% confidence interval, 1.0-1.9). The corresponding odds ratio estimates were close to 1.0 for black women.

CONCLUSIONS

Underweight and extreme obesity may increase the risk of underusing screening mammography. The association between body mass index especially underweight and underuse of mammography might exist primarily in white women.

Virtual colonoscopy for colorectal cancer screening: current status

Computed tomography colonography (CTC) (also known as ‘virtual colonoscopy’) is a noninvasive method of imaging the colon using helical CT. Although CTC has been shown to be useful for certain clinical indications, it has not yet been endorsed as a colorectal cancer screening test. The purpose of this article is to review the current status of CTC for colorectal cancer screening. CTC is an accurate method to detect colonic polyps and to select patients who would benefit from colonoscopy. The major advantages of CTC over conventional colonography include its relatively low risk and greater tolerance by patients. In this article, the CTC procedure and results of clinical trials are reviewed, as well as potential pitfalls related to CTC performance and interpretation. Finally, radiation dose, the discovery of incidental extracolonic findings with CTC, bowel preparation methods, and computer-aided diagnosis are addressed.

Mass screening with CT colonography: should the radiation exposure be of concern?

BACKGROUND & AIMS

Computed tomography colonography (CTC), particularly using noncathartic techniques, has the clear potential to increase compliance for colorectal cancer screening. Because the geometry for CTC is highly advantageous, it can be performed with lower radiation doses than almost any other CT examination. If CTC were to become a standard screening tool for the population age 50 years and older, the potential market in the United States would soon be over 100 million people. Therefore, it is pertinent to consider the radiation exposure and any potential radiation risk to the population from such a mass CTC screening program.

METHODS

Organ doses from CTC examinations can be estimated with standard techniques. These doses can be applied to organ- and dose-specific radiation cancer risk estimates to estimate the excess cancer risk resulting from the radiation from a paired (supine and prone) CTC examination.

RESULTS

The cancer risks associated with the radiation exposure from CTC are unlikely to be zero, but they are small. A best estimate for the absolute lifetime cancer risk associated with the radiation exposure using typical current scanner techniques is about 0.14% for paired CTC scans for a 50-year-old, and about half that for a 70-year-old. These values probably could be reduced by factors of 5 or 10 with optimized CTC protocols.

CONCLUSIONS

In terms of the radiation exposure, the benefit-risk ratio potentially is large for CTC.