NEWSLETTER - August 2012


PREVENTIVE HEALTH- Screening for Breast Cancer

Breast cancer is the most frequently diagnosed cancer in women in western societies. The lifetime risk for women is approximately 1 in 9 in the UK and 1 in 8 in the US. These figures refer to total cancers detected, and do not differentiate between relatively benign lesions and aggressive lesions. Striking differences are noted in the prevalence of breast cancer in different geographic locations. Breast cancer accounts for 28.4 deaths per 100,000 persons in England and Wales, but for only 19.2 deaths per 100,000 persons in France and 5.8 deaths per 100,000 persons in Japan. Possible reasons for these differences include climate, diet, genetic inheritance, environmental toxins, patterns of birth control or breast-feeding, and age at first pregnancy. Women who move from low- to high-prevalence countries seem to acquire the higher risk of their new country.

Breast Cancer

Screening Methods

The two most commonly used screening systems currently in use are breast self examination (BSE) and mammography. Breast self examination is the term used to describe the use of the hands to systematically examine the breasts and the surrounding areas for unusual lumps and shape changes. BSE is usually done on a regular basis, using the same technique each time. This ensures that all areas of the breast are felt and examined thoroughly. The purpose of BSE is to screen for breast cancer and detect breast cancer as early as possible. There are a number of pamphlets available from health authorities and commercial or independent sources that explain how to conduct BSE. There is no scientific evidence that BSE improves survival rates for breast cancer and support for this screening method is diminishing, particularly as it results in many false positives, and unnecessary mammograms and biopsies.
Mammography is the term used to describe the use of low dose ionising radiation to provide a detailed image of the breast. It is capable of detecting 75% of tumours at least a year before their presence can be felt. Screening mammography is used for asymptomatic women and diagnostic mammography is used for further investigations of lumps or other symptoms. Regular breast screening using mammography is recommended in most western countries and nationwide government sponsored screening programmes are generally available. Screening is usually recommended for women between 50 and 70 years, however some screening programmes now commence at 40 years.

Screening Controversies

There is considerable controversy concerning the potential advantages and disadvantages of breast cancer screening, and the facts are often hard to find in the welter of claim and counter claim from the various interest groups. Cancer screening has become a big business, employing many thousands of health professionals, and utilising lots of very expensive medical equipment. Not surprisingly, the participants in this business are reluctant to admit that there are disadvantages to breast cancer screening. This was highlighted by a recent controversy in the UK when the department of Health published a leaflet titled “Breast Screening: The Facts”.
This leaflet had to be withdrawn after strong criticism from health professionals. The leaflet, which was produced by the department responsible for the current screening programme, was adjudged to exaggerate the benefits of screening whilst down playing or ignoring the disadvantages.

Contentious issues currently being discussed in the medical literature include the following:

  • Some members of the medical profession question the efficacy of screening as there is no significant decline in the number of aggressive cancers detected. Early detection of these cancers by the screening programme should result in a decrease in numbers.
  • Survival of screen detected cancers is also being questioned. Recent studies suggest that only 4.3% of screen detected cases have their lives saved as a result of screening. This is at odds with the previously quoted figure of 15%.
  • Since screening programmes were introduced there has been a significant reduction in mortality from breast cancer, however it is not known whether this reduction is due to early detection or better treatment or a combination of both.
  • Screening programmes detect cancers that are not aggressive and these are treated. It has been suggested that for every life saved by screening there will be 10 unnecessary treatments.

    To Screen or Not to Screen

    Before deciding whether to commence screening for breast cancer it is important to consider the potential advantages and disadvantages.

    Advantage of screening

    Screening can reduce the risk of dying from breast cancer. It has been estimated that if 2000 women are screened regularly for breast cancer over a period of ten years, one of these women will benefit fro the early detection of cancer

    Disadvantages of Screening

    False Positives. Approximately 10% of women who have a mammogram will register an abnormality, requiring a repeat mammogram. A further 10% of these women may require a breast biopsy, of which approximately 10% will yield significant result. .During a ten year period of regular screening, it is estimated that an abnormal mammogram will be detected in 50% of the screened women, resulting in a great deal of unnecessary stress and anxiety and many unnecessary repeat mammogram’s and biopsies.

    Unnecessary treatment. Ductal carcinoma in situ is often detected by mammography, and these carcinomas are routinely treated by surgical excision or removal of a breast, followed by chemotherapy or radiotherapy. If left untreated, less than half of these cancers would become invasive. It is estimated that if 2000 women are screened regularly for ten years, ten of these women will receive unnecessary treatment for cancer.

    False negatives Mammography will not detect all cancers.

    A decision to screen for breast cancer should be made on an individual basis, after careful consideration of the available information and detailed discussion with the appropriate health professional. Information in favour of screening can be obtained on many government and medical websites. Information on the negative aspects of breast cancer screening is more difficult to obtain, however www.cochrane.dk and www.stopbreastcancer.org may be helpful in this regard.
    For more detailed information on breast cancer, go to Disease List and click on Breast Tumours.

    DID YOU KNOW – The Brain Consumes 25% of Body’s Energy

    Although the brain represents approximately 2% of body weight, it receives 15% of cardiac output, consumes 20% of body’s oxygen and burns 25% of the body’s glucose. The resting brain consumes 0.1 calories each minute and this increases to 1.5 calories per minute in the active brain. The high metabolic activity of the brain is utilised by scanners to monitor brain activity.

    PET Scan

    Positron emission tomography (PET) measures emissions from radioactively labelled metabolically active chemicals that have been injected into the bloodstream. Different compounds can show blood flow and oxygen and glucose metabolism in the tissues of the working brain. These measurements reflect the amount of brain activity in the various regions of the brain and can be used to differentiate normal from abnormal function.
    Functional magnetic resonance imaging (fMRI) relies on the paramagnetic properties of oxygenated and deoxygenated haemoglobin to see images of changing blood flow in the brain associated with neural activity. This allows images to be generated that reflect which brain structures are activated (and how) during performance of different tasks.
    The high energy demands of the brain have been linked to poor performance of children at school who have low energy breakfasts and poor performance of troops on energy deficient rations.

    NEWS – Exercise Grows Brain Cells

    For many years it was thought that neurons, the nerve cells of the brain, could not be regrown or regenerated. You achieved your maximum number as a young adult and from thereon it was all downhill. In the late 1990’s a number of researchers were able to demonstrate regeneration of neurones (neurogenesis) in the hippocampus of the human brain, and it has been postulated that the regeneration of these neurones is important for memory and learning.

    HippoCampus

    Recent research from the University of Columbia has demonstrated that neurogenesis in the brain may be related to exercise. Experiments in mice had previously demonstrated regrowth of brain neurons in mice who regularly used an exercise wheel compared to those mice deprived of exercise. The new nerve cells were tagged with markers and counted at post mortem. Using MRI scans it was demonstrated that the neurogenesis was correlated with increased blood flow to the area of regeneration in the hippocampus. The researchers then studied two groups of middle aged men, one of which exercised for I hour four times a week. They were able to demonstrate the same areas of increased blood flow in the hippocampus of the men who exercised, as they had previously observed in the exercising mice with increased neurogenesis. They have concluded that these increased areas of blood flow are consistent with the regrowth of brain neurons in the hippocampus.
    This new study adds to a growing base of evidence that the brain benefits from exercise. These benefits included enhancing “executive” cognition, which includes higher-order functions such as planning and reasoning; improving some types of learning; and attenuating neural damage from stress. There is also emerging evidence that physical activity may be protective against neurological disorders, including Alzheimer’s and dementia, Parkinson’s disease, stroke, and spinal cord injury.
    Animal studies indicate that apart from generation of new neurones, exercise may also increase the number of synapses (nerve connections) and glial cells. Much of this new growth may be due to the increases supply of oxygen and nutrients from the improved blood flow, however there is mounting evidence that from animal studies that a neurone growth factor called brain-derived neurotropic factor or BDNF is responsible. Irrespective of the mechanisms involved, the message would seem to be that exercise is good for the brain

    D.E.M