Some of us may find the constant reminder that one should eat healthily, exercise regularly and maintain a normal BMI annoying. The attitude is born out of either a sense of denial or belief: denying that the ill effects of having an unhealthy lifestyle will ever affect one’s health or believing that destiny and not lifestyle will determine if one gets seriously ill or not. Perhaps a recent report from the University of California might make these individuals reconsider.

Researchers studied changes in the prostate gene expression in men, with low-grade prostate cancer, who underwent intensive lifestyle and nutrition intervention over a period of 3 months (PAS 2008; 105: 8369 – 8374). Thirty one men with low-grade prostate cancer, who declined immediate surgery, hormonal therapy or radiation, participated in the study. They agreed to a comprehensive lifestyle change instead. A prostate biopsy was performed prior to initiation of the lifestyle change programme. The 3 month lifestyle modification comprised of a 3-day intensive residential retreat followed by weekly outpatient follow-up by a study nurse. The modifications included a low fat (10% of calories from fat), whole foods, plant-based diet; stress management 60 minutes / day (gentle yoga-based stretching, breathing, meditation, imagery and progressive relaxation), moderate aerobic exercise (walking 30 minutes / day for 6 days / week) and a one hour group support session per week. The diet was supplemented with soy (one daily serving of tofu plus 58 gm of a fortified soy protein powdered beverage), fish oil (3 gm daily), vitamin E (100 units daily) selenium (200 mg daily) and vitamin C (2 gm daily). Another prostate biopsy was performed at the end of the 3 months intervention. The gene expression from the normal prostate tissue obtained before and after the lifestyle changes was compared. At the end of 3 months, they found 48 genes up-regulated and 453 genes down-regulated (simplistically, up-regulation means switched on and down-regulation means switched off) in the prostate tissue. The pathways under the control of these genes were found to be involved in tumorigenesis (formation of tumours). For example, they found a set of down-regulated RAS family oncogenes (RAN, RAB14 and RAB8A). In the prostate, RAN may function as an androgen receptor coactivator and its expression is increased in tumour tissues. (Androgen stimulates prostate cancer to grow and oestrogen can suppress prostate cancer growth. Hence, one of the treatments for prostate cancer is to castrate the patient and remove testosterone, an androgen, from circulation. This manoeuvre will then deprive the prostate cancer its driving force, thus, slowing its growth.)

While this study involves only a small number of patients, if its findings are shown to be true in subsequent larger studies, it will make us sit up and take note. We can no longer blame it all on fate or parents for passing on ‘bad’ genes. In the meantime will you continue with your unhealthy lifestyle habits or might you, just to be on the safe side, adopt a more healthy lifestyle?

In the United Kingdom, the National Bowel Cancer Screening Programme, which involves 2 yearly faecal occult blood screening, is predicted to reduce the colorectal cancer mortality in those screened by 13-15% over the next 20 years (J Med Screen 2008; 15: 163 – 174). The same researchers from London have now published their analysis predicting that realistic lifestyle modifications involving diet and exercise could prevent more colon cancers than screening. The lifestyle modifications are

·         Consuming < 90 g/day of red and processed meat

·         Consuming ≥ 5 portions /day of fruit and vegetables

·         Exercising ≥ 30 minutes / day on ≥ 5 days / week, at least at moderate intensity (equivalent to brisk walking)

·         Alcohol consumption not exceeding 3 units / day for men and 2 units / day for women (half a pint of beer, a single measure of spirits, a glass of wine or a small glass of sherry or port is equivalent to a unit).

They have estimated that adhering to these lifestyle modifications could lead to a 26% reduction in the number of cases of colorectal cancer in the British population (Eur J Cancer Prev epub, February 20, 2009).

Since this is an estimation based on projection, you might not be convinced that lifestyle changes can have such major impact on your lifetime cancer risks. Consider this then. Researchers from Tokyo University of Science examined the effects of consuming broccoli sprouts on Helicobacter Pylori colonization in the stomach. [The WHO has classified H Pylori as a carcinogen. H. Pylori infection gives rise to gastritis, stomach ulcer and stomach cancer. Eradication of H. Pylori infection with triple therapy leads to resolution of gastritis, stomach ulcers and the prevention of stomach cancer.] The researchers studied 48 people with H. Pylori infection. They were randomized to consume either 70 g / day of broccoli sprouts (containing 420 µmol sulforaphane precursor) for 8 weeks or an equal amount of alfalfa sprouts (Cancer Prev Res 2009; 2: 353 – 360). Alfalfa sprouts are rich in phytochemicals but do not contain sulforaphane. 

All the participants had blood, stool and urine samples taken on days 0, 28, 56 and 112. H. Pylori stool antigen (HpSA), a biomarker of H. Pylori colonization, and serum pepsinogens PGI and II, biomarkers of gastric inflammation, were measured. Urea breath test was used to assess severity of H.Pylori colonization. The HpSA level in the broccoli sprout group was reduced by > 40% while it remained unchanged in the alfalfa group. The serum pepsinogens levels were significantly reduced only in the broccoli sprout group. Two months after stopping broccoli sprouts in the diet, the HpSA and pepsinogens levels returned to baseline.

The study showed that broccoli sprout consumption successfully reduced H. Pylori colonization but does not completely eradicate the pathogen. It is unrealistic to expect any form of dietary chemoprevention to completely eradicate the risk of developing a particular disease or cancer. Just like eating broccoli sprouts, the lifestyle changes suggested above will only help to reduce the risk of developing colon cancer but will not eradicate the risk completely. In order to benefit from them, we have to persevere with these lifestyle changes and maintain the changes or habits over the long term.

The ball is now in your court. You decide.

The World Cancer Research Fund (WCRF) and its sister organization, the American Institute for Cancer Research (AICR) in their recent report titled ‘Policy and Action for Cancer Prevention’ stated that approximately one third of common adult cancers in the US may be preventable. (This is not including those which can be prevented by not smoking.) The WCRF and AICR estimated that eating a nutritious diet, being physically active and keeping body fat under control may prevent:

• 38% of breast cancers
• 45% of colorectal cancers
• 36% of lung cancers
• 39% of pancreatic cancers
• 47% of stomach cancers
• 69% of esophageal cancers
• 63% of cancers of the mouth, pharynx, or larynx
• 70% of endometrial cancers
• 24% of kidney cancers
• 21% of gallbladder cancers
• 15% of liver cancers
• 11% of prostate cancers

According to the report, diet, physical activity and limited body fat could prevent 34% of these 12 cancers overall and 24% of all cancers.

A study from the Karolinska Institute followed 45,920 Swedish male conscripts from the period 1969 - 70 for 38 years and examined the effects of overweight in adolescence on subsequent adult mortality (BMJ 2009; 338: b496). Compared with normal weight [body mass index (BMI) 18.5 – 24.9 kg/sq.m] men, the mortality risk in overweight (BMI 25 – 29.9) and obese (BMI ≥ 30) men was increased by 33% and 114%, respectively. The risk was not increased in underweight men, but in those who were extremely underweight, BMI < 17, the risk of mortality was increased by 33%. The risk of mortality in light (1 – 10 cigarettes / day) and heavy (> 10 / day) smokers was also increased by 54% and 111%, respectively, when compared to non-smokers. (Since the start of this study the number of overweight adolescent men in Sweden has tripled and the number of those who are obese has increased 5 fold. Fortunately, the number of smokers has halved.)

Another study looked at the effects of alcohol consumption on the incidence of cancer risk in 1,280,296 women involved in The Million Women Study (J Natl Cancer Inst 2009; 101: 296 – 305). They attended breast cancer screening clinics in the United Kingdom from 1996 to 2001. The average follow-up time was 7.2 years. The 5 categories of alcohol intake were 0 (24%), up to 2 (29%), 3 – 6 (23%), 7 to 14 (19%) and at least 15 (5%) drinks of 10 g of alcohol (= 1 unit) / week. Increasing alcohol intake was associated with an increased risk of specific cancers. The excess cancer incidence of these cancers, up to 75 years of age, with 10 g increase in daily alcohol intake were:

• Oral cavity and pharynx – 1 per 1000
• Oesophagus – 0.7 per 1000
• Larynx – 0.7 per 1000
• Rectum – 1 per 1000
• Liver – 0.7 per 1000
• Breast – 11 per 1000

To put it another way, the researchers estimated that the background incidence of cancers among women in developed countries was 118 cancers diagnosed per 1000 women up to the age of 75 years. Drinking 1 unit per day increased this by an extra 15 cancers per 1000 women and 2 drinks a day  increased this an extra 30 cancers per 1000 women; the majority of the cancers would be breast cancer.

Most cancers are not inherited. For the small proportion of inherited cancers, your cancer risk is not within your control. For most of us, how you lead your life can impact on your cancer risk. Leading a healthy lifestyle does not reduce your cancer risk to zero; it does however reduce your odds of developing cancer. Do not think that regular health checks will save you from cancers. You hope that the checks will help you detect the cancer at an earlier stage, and that is no guarantee either. A healthy lifestyle has no downside. Embracing it might just save your life!