Colon cancer is the third leading cause of cancer in Western societies and in a number of these countries it is the second leading cause of death from cancer. Annual rates of colon cancer vary considerably from 47/100,000 in New Zealand to 4.1 /100,000 in South Central Asia. Rates for Western Europe and North America are approximately similar at 36/100,000. This wide variation is thought to be due to environmental factors, particularly diet.
There are approximately 50,000 deaths from colon cancer in the US each year, 17000 in the UK and 500,000 worldwide. These deaths represent a major failure of preventive health, as colon cancer is a preventable disease. If detected early, colon cancer can be cured by surgical removal of part of the affected bowel. In many cases this procedure can performed using laparoscopy (keyhole surgery).
There are a number of screening tests available for colon cancer, including the following;
FOBT, sigmoidoscopy and colonoscopy have all been shown to improve the early detection of some polyps and cancers and to reduce mortality, however none of these tests has a high degree of sensitivity or specificity, and the search for improved screening tests continues. This has resulted in the introduction of some new screening tests, particularly
Recent publications have suggested that option 3, using an immunochemical occult blood test may be the most effective screening procedure
Effective screening increases the chances of early detection of polyps or tumours and facilitates there removal, which may take place during the screening process. Surgery for the removal of early tumours, if required, is a relatively simple procedure with a high cure rate.
Effective screening has been shown to significantly decrease the morbidity and mortality from colorectal cancer
Current screening methods will not detect all cancers and false positive faecal occult blood tests cab result in unnecessary colonoscopies.
Fasting and the use of bowel cleansing preparations are required for sigmoidoscopy and colonoscopy
There is a minor risk of tears or abrasions to the colon during sigmoidoscopy
The use of sedation during colonoscopy may be hazardous to some patients
Approximately 80% of bowel cancers occur in individuals who are over 60, however current recommendations suggest that screening should commence at 50 years. In individuals who have a family history of disease or a genetic predisposition, screening may be advisable at an earlier age
For further information see Colon Cancer in disease list
When most people think of calcium they think of bones, where 99% of the body’s calcium is stored in the form of hydroxyapatite. However calcium is much more than a building block for the skeleton. Calcium is one of the most important elements in a number of physiological processes, including nerve conduction, muscle contraction and relaxation, endocrine hormone secretion and cell membrane function.
Calcium is absorbed from food in the intestine, excreted by the kidneys and stored in bones. Levels of calcium are tightly controlled by parathyroid hormone, calcitonin, oestradiol and vitamin D, which work together to control the absorption of calcium from the digestive system and the absorption and release of calcium from bones.
Vitamin D stimulates intestinal absorption of calcium and regulates parathyroid hormone release.
Most of the body’s vitamin D is manufactured in the skin by the action of ultraviolet light (sunlight). Individuals who live in areas with limited sunlight are at risk of vitamin D deficiency, which will affect the absorption of calcium by the digestive system. Vitamin D deficiency is relatively common in older individuals and in those suffering from malabsorption syndromes, intestinal disease such as celiac or pancreatitis. A diet deficient in calcium may also result in decreased blood levels of calcium.
Some medications, particularly steroids, may inhibit calcium absorption
Patients with hypocalcaemia (low calcium levels ) are often asymptomatic, however some individuals may experience muscle spasm or cramps, or numbness or tingling in the fingers or toes. Hypocalcaemia may also result in coarse hair, brittle nails and dry skin.
Low calcium levels may result in high bone turnover and osteoporosis in older individuals and bone deformities (rickets) in young children.
For further information see Hyperparathyroidism in disease list
Research at the Children’s National Medical centre in the USA has shown a strong link between low vitamin D levels and asthma. Researchers compared vitamin D levels in a group of African American children with asthma with a set of non-asthmatic healthy controls. The study revealed that 86% of the asthmatic children were vitamin D deficient compared with 19% of the non-asthmatic controls.
It has been postulated that the low vitamin D levels may cause hypocalaemia (low calcium levels) which can cause involuntary muscle contraction including bronchospasm.
Vitamin D deficiency is known to affect bone growth and density, however this study adds to the growing evidence linking vitamin D deficiency to other conditions such as depression and autoimmune disorders.
For further information see Asthma in the disease list