Mammographic densities as a criterion for entry to a clinical trial of breast cancer prevention.

The most convincing evidence that a factor such as dietary fat is causally related to breast cancer would be obtained from a randomised controlled trial in which exposure to dietary fat intake was systematically varied. A limitation of randomised controlled trials of breast cancer prevention, however, is the large sample size required to detect plausible reductions in risk resulting from the intervention. We describe here experience over a period of 9 years with the use of one risk factor for breast cancer as a criterion for entry to a clinical trial of breast cancer prevention. The risk factor used was the presence of extensive densities in the breast tissue on mammography, which has been found by several investigators to be strongly associated with risk of breast cancer. Using this criterion for selection, 1800 subjects of mean age 46 years were enrolled between 1982 and 1986, and again between 1988 and the present. Throughout this period, the point estimate of annual invasive cancer incidence was approximately 6 per 1000 per year. The observed cancer incidence has been consistently 4-5 times the incidence expected from age-specific breast cancer incidence data for women living in Ontario. These data show that the selection of subjects for a clinical trial of breast cancer prevention using the criterion of extensive breast parenchymal densities does identify a group at substantially increased risk of breast cancer. Use of this criterion for the selection of subjects can substantially reduce the sample size required for a clinical trial of a preventive strategy.

Sensitivity and specificity of first screen mammography in the Canadian National Breast Screening Study: a preliminary report from five centers.

Sensitivity and specificity of first screen mammography in a randomized screening trial at five centers are reported. A total of 23,101 women underwent mammography; in 139, breast cancer was detected at first screening; in 20, less than 12 months after first screening; and in 47, at second screening. All 206 cancer cases were histologically confirmed, and 174 were defined as being detectable at first screening. Average length of follow-up for all women was 3.2 years. Interpretations of first screen mammograms by the center radiologists were matched to known outcomes. Simultaneous blind review was performed by a single reference radiologist with mammograms from all 206 cancer cases and those of a random sample of 739 women not known to have breast cancer at 15 months or more after initial screening. Overall, the five screening centers achieved a sensitivity of 69% (range, 60%-78%), a specificity of 94% (range, 93%-96%), a positive predictive value of 8.6% (range, 3%-16%), and a negative predictive value of 99.7% (range, 99.6%-99.9%).

Needle-guided breast biopsy for mammographic abnormalities in 561 patients.

Between 1977 and 1983, 561 consecutive patients underwent 595 surgical biopsies for suspicious mammographic lesions with negative clinical correlation. The procedure consisted of preoperative needle localization, with or without immediate radiologic examination of the biopsy specimen, depending on the presence or absence of microcalcifications in the mammographic lesion. Eighty-four carcinomas were found. Of these, 60 (71%) were infiltrating carcinoma and 24 (29%) were noninvasive carcinoma. The carcinoma yield was 24.2% in the patients with lesions involving foci of microcalcifications and 9% in those lesions without calcifications. Surgical treatment of infiltrating carcinoma consisted of 39 modified radical mastectomies, 10 (25.6%) of which were associated with positive nodes, 16 partial mastectomies with axillary dissection, 3 (18.7%) of which were associated with positive nodes, and 5 wedge resections. Treatment of noninvasive carcinoma consisted of 19 partial mastectomies with axillary dissection and 5 modified radical mastectomies. None of these were associated with positive nodes. Modified radical mastectomy was used with decreasing frequency. Of the 10 patients with infiltrating carcinoma and positive axillary nodes treated by modified radical mastectomy, 7 had one to three involved nodes and 3 had four or more; of those with positive nodes treated by partial mastectomy, 1 had one to three involved nodes and 2 had four or more. These results confirm the correlation between suspicious mammographic non-clinical lesions and breast carcinoma.

Observer variation in the interpretation of xeromammograms.

We have examined variation in the interpretation of xeromammograms among radiologists designated to take part in a Canadian multicenter randomized controlled trial of screening for breast cancer. Radiologists read 100 xeromammograms comprising 10 histologically proved cancers, 40 benign abnormalities, and 50 normal films. Radiologists' opinions differed widely on the frequency of suspected or identified cancer. The diagnostic category "suspicion of cancer" or "cancer" was selected by radiologists for 10-55% of the films, and biopsy or aspiration was recommended for 21 to 53% of patients whose films were examined. Agreement on specific diagnostic categories was greatest for the diagnosis of cancer; agreement was least for the diagnosis of benign abnormalities and intermediate for the diagnosis of normality. Known cancers were in general correctly identified. These results indicate a need for development of methods to reduce observer variation in a interpretation of xeromammograms while preserving diagnostic sensitivity and validity. Results also emphasize the importance of developing strategies to ensure quality control in multicenter trials.

Sophisticated radiology in otolaryngology. I. Diagnostic imaging: roentgenographic (x-ray) modalities.

Conventional radiography is now complemented by a large range of newer radiologic diagnostic techniques, involving both roentgenographic and non-roentgenographic modalities. It is the purpose of this presentation to present these new roentgenographic modalities in graphic form, and demonstrate their application to otolaryngic diagnosis. The major roentgenographic modalities which will be stressed are: xeroradiography, angiography, and computerized tomographic scanning.

Sophisticated radiology in otolaryngology. II. Diagnostic imaging: non-roentgenographic (non x-ray) modalities (ultrasound, nuclear medicine, thermography).

Newer forms of radiologic diagnostic imaging now include non-roentgenographic modalities such as ultrasound, nuclear medicin, and thermography, all of which can be applied to otolaryngology. It is the purpose of this presentation to demonstrate these modalities, and indicate their clinical application, yet in its earliest stages, to otolaryngology.