Sigmoidoscopy is one of the most reliable medical procedures used in diagnosing colorectal cancer in present. Through the means of sigmoidoscopy, oncologists are able to timely detect signs of physiological abnormalities at the level of the colon. Sigmoidoscopy can be either performed with an immobile or a flexible scope, depending on the segments of the colon that require screening. However, due to the fact that rigid sigmoidoscopy provides limited visibility, doctors usually prefer using a flexible scope instead. In addition, flexible sigmoidoscopy is less likely to cause discomfort to patients. Flexible sigmoidoscopy involves using a 60-cm scope that can easily detect cancerous colonic polyps, tumors or adenomas situated in various regions of the large bowel.

Sigmoidoscopy is primarily recommended for patients that present no clear symptoms of colorectal cancer. The procedure involves very few risks and it is well tolerated by most patients. Post-sigmoidoscopy symptoms are usually mild and disappear completely within a few hours or days. Such symptoms may include abdominal pain and bloating, internal discomfort and rarely, minor rectal injuries.

Although sigmoidoscopy is a simple procedure, it is important to note that it may not be appropriate for some patients. Sigmoidoscopy is not recommended to people who have suffered bowel surgery, people with acute peritonitis or people with acute diverticulitis. In some cases, the procedure may also be contraindicated for people who have recently suffered abdominal surgery.

Before receiving an examination with the sigmoidoscope, patients are administered bisacodyl and magnesium citrate. Combined with enemas, these medications are used for preparing the large bowel for sigmoidoscopy. The preparation treatment for sigmoidoscopy is very important for increasing the visibility inside the bowel. The actual procedure is very quick and it generally causes minimal discomfort to patients. Post-sigmoidoscopy complications are also very rare.

Corroborated with colonoscopy screening and barium enemas, sigmoidoscopy is very effective in timely spotting traces of malignant activity at the level of the large bowel. Since it has been introduced in the process of diagnosing colorectal cancers, sigmoidoscopy has considerably decreased patients’ mortality rate.

Diet is one of the most important lifestyle factors and has been estimated to account for up to 80% of cancers of the large bowel, breast, and prostate. Diet affects the risk of many other cancers, including cancers of the lung, prostate, stomach, esophagus and pancreas.

Prostate Cancer:

High consumption of meat, especially red meat, substantially increases the risk of prostate cancer.

Vegetables, especially cooked tomatoes, reduce the risk of prostate cancer. In one clinical trial, the role of Vitamin E as a prostate cancer reducing factor was established. In this study there was a 32% decrease in prostate cancer incidence and 41% decrease in prostate cancer mortality in people receiving Vitamin E supplements when compared to controls.

Breast Cancer:

In Japan, people consume Tofu, a soya product. It contains isoflavones that moderate the estrogen receptors in the body such as breast tissue. The incidence of breast cancer is low in Japan when compared to Western women; only 1/4th of the mortality rate of Western women. Japanese women’s low fat diet, high fish consumption and drinking green tea also decrease their breast cancer risk.

One case control study found that regular consumption of soy foods was associated with a marked decrease in breast cancer risk in premenopausal women. No effect in post-menopausal women.

A Japanese case-control study also found that tofu intake (3 times/wk compared with less than 3 times/wk) was associated with decreased risk of breast cancer in premenopausal women. Again, soy intake was not protective against post-menopausal breast cancer.

In one study conducted in America, the relation between soy intake and breast cancer risk found that tofu consumption was protective in both premenopausal and post menopausal Asian women.

Lung Cancer:

Lung cancer risk is substantially decreased by a variety of carotenoids. Carotenoids act as antioxidants and thus minimize cell damage.

One study in Boston focused on the effect of different types of carotenoids on lung cancer risk. It was observed that lung cancer risk was significantly lower in subjects who consumed a diet high in a variety of carotenoids. This was especially true with non-smokers who had 63% less risk.

One study conducted in Hawaii reported further evidence for a protective effect from certain carotenoids against lung cancer and that greater protection was afforded by consuming a variety of vegetables compared to only foods rich in a particular carotenoid.

Stomach Cancer:

Nitrates in food and other preservatives added to food including meat are converted into ‘nitrites’ in the human stomach. The nitrites undergo nitrosation to form ‘nitrosamines’ and ‘nitrosamides’. This increases the risk of stomach cancer in people eating vegetables from nitrate rich soil.

In one study, Vitamin C appeared to protect against the risk of stomach cancer by inhibiting formation of nitrates in stomach.

Cancer of the stomach is 5 times more common in Japanese people compared to Western populations. When Japanese people migrated to the United States, they progressively acquired the low incidence of the US due to changes in their diets.

In one study conducted in Hawaii that involved both Japanese and Caucasians, the stomach cancer risk was associated with consumption of rice, pickled vegetables, and dried/salted fish, and a negative association with vitamin C intake.

One ecological study in Belgium showed a relation between the nitrate and salt consumption and stomach cancer. The analysis of this model showed that the significance of nitrate as a risk factor for stomach cancer mortality increased markedly with higher sodium levels.

Dietary habits and stomach cancer risk was studied in Shanghai, China. According to this study, risks of stomach cancer were inversely associated with high consumption of several food groups, including fresh vegetables and fruits, poultry, eggs, plant oil, and some nutrients such as protein, fat, fiber, tea and antioxidant vitamins.

By contrast, risks increased with increasing consumption of dietary carbohydrates, frequent consumption of preserved, salty or fried foods and hot soup/porridge, with irregular meals, speed eating and binge eating. This provides evidence that diet plays a major role in stomach cancer risk.

No single food can completely prevent cancer but a balanced combination of different groups can help. Appropriate diet can prevent 3-4 million cancers each year.