Mammography in Symptomatic and Asymptomatic Patients

Planning of randomized early detection trials

Consider a randomized clinical trial to evaluate the benefit of screening an asymptomatic population. Suppose that the subjects are randomized into a usual care and a study group. The study group receives one or more periodic early detection examinations aimed at diagnosing disease early, when there are no signs or symptoms. Early detection clinical trials differ from therapeutic trials in that power is affected by: i) the number of exams, ii) the time between exams and iii) the ages at which exams will be given. These design options do not exist in therapeutic trials. Furthermore; long-term follow-up may result in a reduction of power. In general, power increases with number of examinations, and the optimal follow-up time is dependent on the spacing between examinations. Clinical trials in which the usual care group receives benefit are also discussed. Two designs are discussed, for example the 'up-front design' in which all subjects receive an initial exam and then are randomized to the usual care and study groups and the 'close-out design' in which the usual care group receives an exam which is timed to be given at the same time as the last exam in the study group. Both families of designs significantly reduce the power. Power calculations are made for two clinical trials, which actually used these two designs.

Interpreting hemoglobin and water concentration, oxygen saturation, and scattering measured in vivo by near-infrared breast tomography

Near-infrared spectroscopic tomography was used to measure the properties of 24 mammographically normal breasts to quantify whole-breast absorption and scattering spectra and to evaluate which tissue composition characteristics can be determined from these spectra. The absorption spectrum of breast tissue allows quantification of (i) total hemoglobin concentration, (ii) hemoglobin oxygen saturation, and (iii) water concentration, whereas the scattering spectrum provides information about the size and number density of cellular components and structural matrix elements. These property data were tested for correlation to demographic information, including subject age, body mass index, breast size, and radiographic density. Total hemoglobin concentration correlated inversely to body mass index, likely because lower body mass indicates proportionately less fat and more glandular tissue, and glandular tissue contains greater vascularity, hence, more total hemoglobin. Optical scattering was correlated to breast diameter, subject age, and radiographic density. In the radiographic density, fatty breasts had low scattering power and extremely dense breasts had higher values. This observation is consistent with low attenuation of conventional x-rays with fat and higher attenuation in glandular tissues. Optically, fatty tissues have large scatterers leading to a low scattering power, whereas glandular or fibrous tissues have more cellular and collagen-based structures that lead to high scattering power. The study presents correlative data supporting the hypothesis that optical measurements of absorption and scattering can provide physiologically relevant information about breast tissue composition. These breast constituents vary significantly between individuals and can be altered because of changes in breast physiology or pathological state.

A pilot study of eye movement during mammography interpretation: eyetracker results and workstation design implications

Digital mammography can potentially improve mammography image and interpretation quality. On-line interpretation from a workstation may improve interpretation logistics and increase availability of comparison images. Interpretation of eight 4k- x 5k-pixel mammograms on two to four 2k- x 2.5k-pixel monitors is problematic because of the time spent in choosing which images display on which monitors, and zooming and roaming on individual images that are too large to display completely at full resolution. The authors used an eyetracker to measure radiologists viewing behavior during mammography interpretation with film on a viewbox. It was observed that a significant portion of the mammographers' time is spent viewing "comparison pairs" (typically two or more comparisons per case), such as the left mediolateral and craniocaudal images or old and new images. From the eyetracker measurements, we estimated that the number of image display, roam, and zoom operations decreases from an average of 64 for one monitor to 31 for four monitors, with the largest change going from one to two monitors. We also show that fewer monitors with a faster response time is superior to more monitors with a slower response time. Finally, the authors demonstrate the applicability of time-motion analysis to mammographic workstation design.

Breast cancer in young patients

BACKGROUND

Breast cancer in a young person is considered by many to be a rare and very aggressive disease. Theories regarding the aggressiveness of the disease are varied. This study was undertaken in an attempt to help formulate guidelines regarding screening for and treatment of breast cancer in the young patient.

PATIENTS AND METHODS

A retrospective review was undertaken of 81 breast cancer patients aged < or = 35 years who underwent definitive surgical treatment. All patients were treated at a single institution.

RESULTS

Overall 5- and 10-year survival rates were 65% and 49%, respectively. In patients with disease localized to the breast, 5- and 10-year rates were 89% and 78%, respectively. There was no significant difference in survival with respect to age or date of diagnosis, nor was there a difference in cancer stage distribution. The only major determinant of survival was stage at the time of diagnosis.

CONCLUSIONS

We conclude that young age does not seem to be directly related to the "aggressiveness" or "virulence" of breast cancer, especially among patients with localized disease. These results underscore the need for aggressive and early treatment of these patients. The improved survival with early detection is a valid argument for careful screening, even among very young patients.

New modalities in breast imaging: digital mammography and magnetic resonance imaging

Mammography is currently the only screening method available with proven capability to diagnose nonpalpable breast cancer. However, mammography does not detect all cancers. Cancers are more difficult to detect in radiographically dense breasts because lesions are obscured by breast tissue. Digital mammography and magnetic resonance imaging of the breast may minimize the problems associated with screening dense breasts. If these methods prove to be useful, more cancers could be detected at an earlier stage.

Effects of lead time, length bias, and false-negative assurance on screening for breast cancer

This article presents a model of breast cancer screening programs. The model shows the effects of the screening threshold, screen sensitivity, and false-negative assurance on the cumulative mortality rate in the screened population. It shows that factors of screen design and a penalty associated with false-negative assurance can result in excess mortality rates in screened populations--especially in those age classes in which the incidence of rapidly growing tumors is high. Factors related to the magnitude of this effect are described.

Breast cancer survival among women under age 50: is mammography detrimental?

Great uncertainty exists about the benefit of detecting breast cancer by mammography in women under 50 years of age. We have reviewed the survival of patients aged 49 years or less whose cancers were detected by mammography alone. 117 women under the age of 50 years were diagnosed with breast cancer between 1978 and 1991 based only on an abnormal mammogram. Ductal carcinoma in-situ (DCIS) was found in 47 (40%) of these women, whilst 70 (60%) had infiltrating ductal or infiltrating lobular carcinomas. During the same interval, 928 women in this age group presented with palpable breast cancer. DCIS was diagnosed in 82 (9%) of these women, whilst 846 (91%) had infiltrating carcinoma. Among the infiltrating cancers detected by mammography alone, 50% were stage I, whilst only 30% of the women with palpable cancers were stage I. Five-year survival for all mammographically detected cancer patients was 95%, whereas for women with palpable cancers the survival was 74% (p < 0.00005). If DCIS is not included, the corresponding survivals are 91% for mammographically detected infiltrating cancers and 72% for palpable infiltrating cancers. Only 1 woman who died among those with palpable cancer had had a mammogram before diagnosis. Our data contradict the suggestion that women under 50 are put at a survival disadvantage by undergoing mammography. We believe that investigators who have reported negative results in this age group must examine other causes for their results.

Overview of guidelines for screening

Controlled trials of screening for breast cancer have proven that (1) for women older than 50 years of age, screening with single-view or two-view mammography, at intervals of 1 to 3 years, with or without clinical examination reduces mortality; (2) annual screening with two-view mammography and clinical examination and emphasis on breast self-examination (BSE) can reduce mortality for women from 40 to 49 years of age; (3) screening this age group with single-view mammography, at intervals of 20 months or longer, without clinical or BSE results in excess mortality in women screened; (3) screening this age group annually with poor quality mammography, weakly interpreted, with some clinical examination results in excess deaths in screened women. If screening women 40 to 49 years of age is to be suggested there is no reason to suggest a model that has been proven to be counterproductive.