Breast cancer screening controversies

BACKGROUND: The Cochrane Collaborative, a respected independent review body, recently published a meta-analysis of the effectiveness of screening mammography in decreasing breast cancer mortality. Based on the results of two controlled trials they judged to be of medium validity, they concluded that screening mammography was unjustified. In contrast, the US Preventive Services Task Force recently updated their screening recommendations, and based on a meta-analysis of the same randomized controlled trials, they recommended screening mammography for all women starting at age 40 years. Additionally the Canadian Task Force on Preventive Health Care no longer recommends breast self-examination (BSE). This article reviews the controversies regarding breast cancer screening. METHODS: We performed a systematic review of the literature using keywords and cross-referencing articles. We also used automated data from the Breast Cancer Screening Program at Group Health Cooperative to determine the sensitivity of the clinical breast examination (CBE) at our institution. For the latter we included all cancers diagnosed within 1 year of a screening examination and then determined which of those had been found by CBE. RESULTS: Although most screening studies have shown that mammography decreases breast cancer death, there are controversies about the validity of some of the randomized controlled screening mammography trials. These controversies have led to different conclusions about the efficacy of screening mammography. Evidence is limited about the optimal interval for screening mammography. No studies have directly tested the efficacy of the CBE in decreasing breast cancer mortality. At Group Health Cooperative, 8% of all diagnosed breast cancers were found by the CBE alone (negative mammogram). Whether this 8% incremental increase in case finding leads to decreased breast cancer deaths is unknown. There is good evidence that training women to perform BSE does not increase breast cancer diagnoses or decrease breast cancer deaths. CONCLUSION: There are limitations to randomized controlled trials and meta-analyses. The balance of the evidence still favors screening mammography in women aged 40 years and older at least every 2 years. The independent incremental benefit of the CBE, when added to mammography, in decreasing breast cancer mortality is unknown. Population-based education and training to do BSE are unlikely to lead to decreased breast cancer deaths. Many women find their own breast cancers, so women need to pay attention to symptoms or changes in their breasts.     

Malnutrition: trials and triumphs

Severe malnutrition is uncommon but often fatal, particularly in very young infants or when oedema is present. Another major contributor to mortality is undiagnosed infection. Three pilot studies have recently been performed in severely malnourished patients in therapeutic feeding centres in sub-Saharan Africa. In each, a practical management problem was addressed and a potential solution tested. Three conclusions were reached: young breastfeeding infants were best managed using a supplemented suckling technique; routine antibiotics from admission reduced mortality; and in adults with oedematous malnutrition, therapeutic diets with a lower-than-usual protein:energy ratio were effective in reducing mortality and permitting catch-up weight gain.     

A mobile screening unit, practicalities and problems.

The need for a mobile screening unit to travel throughout Scotland to measure and modify cardiovascular risk factors in the apparently healthy working population was fulfilled by the conversion of a double-decker bus. The aim of the project was to assess the incidence of risk factors in healthy individuals and to modify their risk factors by individual counselling. Many unforeseen practical problems were encountered and overcome during the planning stage and during the project. The team of specially trained staff spent three and a half years screening more than 20,000 people throughout Scotland. This project provides a model for other screening projects involving a multicentre/scattered cohort.     

Genetic screening

Current approaches to genetic screening include newborn screening to identify infants who would benefit from early treatment, reproductive genetic screening to assist reproductive decision making, and family history assessment to identify individuals who would benefit from additional prevention measures. Although the traditional goal of screening is to identify early disease or risk in order to implement preventive therapy, genetic screening has always included an atypical element-information relevant to reproductive decisions. New technologies offer increasingly comprehensive identification of genetic conditions and susceptibilities. Tests based on these technologies are generating a different approach to screening that seeks to inform individuals about all of their genetic traits and susceptibilities for purposes that incorporate rapid diagnosis, family planning, and expediting of research, as well as the traditional screening goal of improving prevention. Use of these tests in population screening will increase the challenges already encountered in genetic screening programs, including false-positive and ambiguous test results, overdiagnosis, and incidental findings. Whether this approach is desirable requires further empiric research, but it also requires careful deliberation on the part of all concerned, including genomic researchers, clinicians, public health officials, health care payers, and especially those who will be the recipients of this novel screening approach.     

Genetic screening

Medicine, Health Care and Philosophy -     

Current controversies in endocrinology: screening of asymptomatic elderly for subclinical hypothyroidism

Thyroid disorders are common in elderly patients. In fact, the most common form of thyroid dysfunction in the elderly is subclinical hypothyroidism. Subclinical hypothyroidism is a biochemical state characterized by an increased serum thyroid-stimulating hormone and normal levels of serum-free T4 and free T3. Much attention has been focused on this clinical entity recently, but it remains controversial whether early thyroid replacement therapy improves outcomes in elderly patients with asymptomatic subclinical hypothyroidism. There is a dearth of critical evidence on the effects of subclinical hypothyroidism on target tissues, the natural history of early thyroid dysfunction, and the net benefits and harms of long-term treatment with thyroid hormones. This article reviews the available information on the aging thyroid gland, subclinical hypothyroidism, and issues concerning treatment in asymptomatic elderly patients.     

Vitamin supplements: current controversies.

Supplemental use of vitamins to prevent disease constitutes a major commercial enterprise in the United States. The efficacy of such use, or even the need for intakes above that which can be supplied by means of diet alone, has been the source of considerable controversy in the medical and scientific fields. Recently published data have given strong support to several of the claims for major benefits of disease prevention, including that of cancer, cardiovascular disease, carpal tunnel syndrome, and neural tube defects, to name just a few. The purported benefits for supplemental vitamin usage are discussed for these diseases, along with a call for a re-evaluation of the underlying philosophy of the Recommended Dietary Allowances, or consideration of their abolition, based on newly emerging data.     

Capacity to consent: issues and controversies.

Capacity to consent has major ethical and legal implications, but it is often poorly understood and inadequately practiced. Varied literature on the subject is reviewed with a view to discuss the legal and clinical aspects and strategies to improve current practice.