Biologic characteristics of breast cancer detected by mammography and by palpation in a screening program: a pilot study.

OBJECTIVE: To compare the histopathologic features and expression of p53 and c-erb B2 in the tumours detected by mammography only (clinically occult tumours) and the tumours detected by a nurse examiner (clinically palpable tumours). SETTING: London branch of the Ontario Breast Screening Program, which uses both clinical breast examination and mammography as screening methods. INTERVENTIONS: Pathologic review and immunohistochemical staining of all tumours detected between 1990 and 1993. OUTCOME MEASURES: Categorization of tumours by detection method and analysis of tumour size, grade, type, lymph node status and c-erb B2 and p53 expression in each group. RESULTS: From 1990 to 1993, 131 tumours were detected in patients ranging in age from 50 to 85 years (median 63 years). Sixty-seven occult tumours and 64 palpable lesions were detected. The occult tumours were significantly smaller (1.34 cm v. 2.29 cm, p < 0.0001) than the palpable ones and included a higher proportion of special-type lesions and ductal carcinoma in situ (43.3% v. 10.9%, p < 0.0001). Occult invasive carcinomas were of lower grade than palpable carcinomas (68.4% grade 1, 21.1% grade 2, 10.5% grade 3 v. 32.8% grade 1, 36.1% grade 2, 31.1% grade 3, p < 0.0001). Fewer occult lesions showed axillary nodal metastases (19.6% v. 40.6%, p = 0.02). No statistically significant differences were found for p53 or c-erb B2 positivity between the 2 groups. CONCLUSION: Tumours detected by different screening methods in a screening program have different pathologic characteristics.

The relative diagnostic impact of screening mammography and physical examination.

OBJECTIVE: To determine the relative diagnostic impact of screening mammography and physical examination. METHODS: Data from the first 3.5 years of operation of the Ontario Breast Screening Program's regional facility in London were analyzed. A total of 14,646 women underwent screening, which involved both mammography and physical examination. The authors examined the relative contribution of the two types of examination according to detection rate, as well as size, stage and histologic type of the identified breast cancers. RESULTS: In total, 135 cancers were detected. Mammography revealed 131 (97.0%) of all cancers, whereas physical examination revealed only 66 (48.9%). Furthermore, the lesions detected by mammography were generally smaller and found at an earlier stage. CONCLUSION: Although most other screening programs involve mammography only, physical examination did make a contribution to the detection rate at the authors' facility. However, in an era of declining resources and cost containment, critical analysis of the value added by physical examination is necessary.

A prospective randomized clinical trial comparing two film-screen systems for chest radiography.

OBJECTIVE: To compare conventional and asymmetric film-screen chest radiography systems in a prospective, randomized trial. PATIENTS AND METHODS: Posteroanterior and lateral films were obtained with each system for one healthy volunteer and 49 consenting patients referred from pulmonary clinics and wards (for a total of 27 male and 23 female subjects ranging in age from 16 to 82 [mean 58] years). The radiographs, obtained and presented in random order, were reviewed and rated independently by two experienced radiologists and one resident in radiology; all observers were blinded to patient identification and film type. The Wilcoxon signed rank sum nonparametric test for paired samples was used to test for significant differences between the two film-screen systems. A second evaluation involving direct (blinded) comparison of the two types of films was then performed for each of the 25 patients in whom abnormality was noted during the first evaluation. RESULTS: For the posteroanterior radiographs, the asymmetric film-screen system was significantly better for assessing the trachea and mainstem bronchi, the descending thoracic-aortic edge, the left paraspinal line, the thoracic vertebral body interspace and the azygo-esophageal line (p < 0.05), whereas the conventional system had superior conspicuity in the lateral subpleural zones (p < 0.05). For the lateral radiographs, the asymmetric system was superior for assessing retrosternal lung markings (p < 0.05) but inferior for assessing fissures (p < 0.05). CONCLUSIONS: In general, the asymmetric system was superior for assessing mediastinal features and inferior for assessing the lateral subpleural zones in the posteroanterior radiographs. The asymmetric system was superior for assessing retrosternal lung markings and inferior for assessing fissures in the lateral radiographs. The results for the posteroanterior radiographs were consistent with the results of nonblinded studies reported elsewhere.

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.

Pneumoperitoneum after laparoscopic cholecystectomy: frequency and duration as seen on upright chest radiographs.

OBJECTIVE: This study aimed to determine the frequency and duration of pneumoperitoneum after laparoscopic cholecystectomy, as detected on upright chest radiographs. MATERIALS AND METHODS: Fifty-five patients who underwent laparoscopic cholecystectomy were studied prospectively. Upright posteroanterior chest radiographs were obtained 6 hr after surgery (day 1); additional radiographs were obtained on days 2, 4, 7, and 14, if required, until the pneumoperitoneum resolved. A perpendicular measurement of any pneumoperitoneum detected between the diaphragm and the liver was obtained. The pneumoperitoneum was graded as absent, trace (1-5 mm), mild (6-10 mm), or moderate (10-15 mm). RESULTS: No evidence of pneumoperitoneum was seen on chest radiographs taken 6 hr after surgery (day 1) in 27 (54%) of the 50 patients who completed the study. Of the remaining 23 patients (46%), all but one showed resolution of the pneumoperitoneum in the first week. Of these 23 patients, 17 showed trace pneumoperitoneum and six showed mild pneumoperitoneum on chest radiographs. CONCLUSION: Despite the use of carbon dioxide gas during laparoscopic cholecystectomy, a significant number of patients have postsurgery pneumoperitoneum that is visible on upright chest radiographs. The pneumoperitoneum resolves in most patients within the first week after surgery.

Accuracy of portable chest radiography in the critical care setting. Diagnosis of pneumonia based on quantitative cultures obtained from protected brush catheter.

Sixty-six supine portable chest radiographs done on the day of bronchoscopy in 62 critical care unit patients suspected of having pneumonia were examined in a blinded fashion by two radiologists. Quantitative culture results obtained from protected brush catheter (PBC) specimens were compared with chest radiograph scores. For one observer, the sensitivity of the chest radiograph for predicting the presence of positive culture results was 0.60, specificity was 0.29, overall agreement was 0.41, positive predictive value was 0.34, and negative predictive value was 0.55. For the second observer, the values were as follows: sensitivity, 0.64; specificity, 0.27; overall agreement, 0.41; positive predictive value, 0.35; and negative predictive value, 0.55. The kappa statistic was calculated at 0.27 indicating marginal interobserver reproducibility. We conclude the portable chest radiograph in the critical care setting is not accurate in predicting the presence of pneumonia when the diagnosis is based on quantitative cultures obtained from protected brush catheter specimens.