Monday, July 15, 2013 C7
HEALTH
Screening the best hope of catching killer ............................................... Hazel Knowles life@scmp.com Erica had never considered herself at risk of colorectal cancer before 2006, and was unaware it was one of Hong Kong’s biggest cancer killers. But after her mother died from colon cancer in 2006, Erica decided to undergo screening. In January 2008, she was diagnosed with the same cancer that had killed her mother. Alarmingly, despite the absence of symptoms, it was at an advanced stage and had already spread to her liver. “I was devastated,” recalls Erica, now aged 50. “My son was only 12 years old, and as my mother had died so quickly, I thought I would not live to see him go to secondary school.” In 2010, there were 4,370 new cases of colorectal cancer, the Hong Kong Cancer Registry says. It is one of the most common cancers in Hong Kong, second only to lung cancer in men, and breast cancer in women. Thirty years ago, it was much less common, with only 818 cases in 1983. But since then the number has risen by about 3 per cent a year. It caused 1,864 deaths in 2010. According to Professor Yuen Siu-tsan, medical adviser to the Hong Kong Cancer Fund, the city’s growing prosperity has led people to switch to a diet rich in red meat, animal fats and processed food. This is to blame for the dramatic increase in colorectal cancer. “Colorectal cancer is a disease of wealthy societies. When Hong Kong was less developed, the incidence rate was much lower. But as Hong Kong has become more prosperous, the incidence rate
Hong Kong became more prosperous, so the incidence rate has increased PROFESSOR YUEN SIU-TSAN
Regular cancer screenings help to halt the disease. Photo: Corbis
has increased,” says An honorary clinical professor in the department of pathology at University of Hong Kong, Yuen says as many of 85 per cent of cases were sporadic and believed to environmentally linked to diet and lifestyle. “With lung cancer on the decline, it is only a matter of time before colorectal cancer overtakes it to become the number one killer cancer in Hong Kong,” says Yuen. Ironically, colorectal cancer is one of the most easily preventable. Screening can detect abnormalities before they become cancerous. Building public awareness of the disease has become a priority of the Hong Kong Cancer Fund. A spokesman for the fund says the message is that lifestyle changes can help reduce the risk of developing the disease, and early detection saves lives. Two types of screening are available: a non-invasive method called faecal occult blood test and a colonoscopy. The blood test involves examining stool samples for blood produced by growths in the colon. But it needs to be done regularly and is not capable of detecting abnormal growths at a precancerous stage. According to Professor Law Wai-lun, a clinical professor in the department of surgery at University of Hong Kong’s Li Ka Shing Faculty of Medicine, this is why the colonoscopy is considered the gold standard for investigations of the colon. Like most experts, Law recommends people consider screening with this method at the age of 50, and then every 10 years afterwards. With a colonoscopy, the colon is screened using a flexible tube fitted with an endoscopic high-definition camera passed through the whole colon via the rectum. There is also a version called a sigmoidoscopy which just screens the lower bowel. This method, which can be performed as a day case under mild sedation, allows cancer to be detected at very early stages. It also effectively prevents it by detecting it at a pre-cancerous stage as abnormal growths called polyps, which can develop into cancer over 10 to 15 years. Many experts are calling for a government screening programme offering colonoscopies to people over the age of 50. This would help early diagnoses which, in turn, could save lives and prevent people like Erica undergoing the trauma of treatment. With hindsight, Erica wishes she had heard about colonoscopies earlier in her life. Her own battle with cancer spanned three years and included chemotherapy, three surgical procedures, and targeted therapy. But she is now clear, and takes comfort that her experience inspired her two siblings to have a colonoscopy.
CHIP
SHAPE New research shows that overeating may not be the cause of obesity. It could be due to a metabolic reaction brought on by certain types of sugars, says Jeanette Wang
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t’s a logical equation: if you earn more money than you spend, you’ll have cash in hand. Likewise, if you consume more calories than you expend, you’ll be carrying extra calories – and therefore put on weight, right? Wrong – according to a recent article in the journal BMJ, the obesity equation isn’t that straightforward. Gary Taubes, co-founder of the Nutrition Science Initiative in San Diego, says the history of obesity research is one of two competing hypotheses – and that the wrong hypothesis won. This “energy balance” hypothesis – that overeating is the cause of obesity – along with substandard science, has exacerbated the obesity crisis, and the related chronic diseases, Taubes says. He thinks another look at the causes of obesity is needed, if we are to make any progress with the crisis. In Hong Kong, as in most countries, obesity is on the rise. About 37 per cent of the population aged 18 to 64 were classified as overweight or obese (a body mass index of 23 and above), including 18.8 per cent as obese, in last year’s Behavioural Risk Factor Survey. A person’s beliefs about causes of obesity can affect one’s weight, a new study published in the journal Psychological Science has found. From an initial online survey, researchers Brent McFerran of University of Michigan and Anirban Mukhopadhyay of Hong Kong University of Science and Technology discovered that people seem to subscribe to one of two major beliefs about the primary cause of obesity: poor diet or a lack of exercise. In a series of studies in South Korea, the US and France, the
researchers found that people who viewed diet as obesity’s primary cause had lower body mass indexes than those who implicated lack of exercise. They studied Hongkongers and found that participants who were primed to think about the importance of exercise ate more chocolate than those primed to contemplate diet. A Canadian study showed that participants who linked obesity to lack of exercise ate significantly more chocolates than those who linked obesity to diet. The “energy balance” hypothesis, Taubes says, is largely the product of the influential thinking of two physicians – the German diabetes specialist Carl von Noorden at the beginning of the 20th century, and the American internist and clinical investigator Louis Harry Newburgh, a quarter of a century later. “Its acceptance as dogma came about largely because its competing hypothesis – that obesity is a hormonal, regulatory disorder – was a German and Austrian hypothesis that was lost with the anti-German sentiment after the second world war, and the subsequent embracing of English, rather than German, as the lingua franca of science.” But does aberrant behaviour really cause obesity? The
Another look at the causes of obesity is needed if we are to make any progress with the crisis
LAB REPORT ...................................................................................... Jeanette Wang jeanette.wang@scmp.com
Women’s wobbly woes Two-thirds of women in Hong Kong are dissatisfied with their body shape, according to a survey conducted by The Nielsen Company. Five hundred women aged 25 to 49 participated in the poll, sponsored by global aesthetic device company Syneron Medical and presented at last week’s Asian Dermatological Congress in Hong Kong. Women in Taiwan and Australia were also surveyed, with 75 per cent and 46 per cent expressing dissatisfaction respectively. The key concerns in all three populations were “love handles”, “bra fat” and bulging tummies.
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Eczema leaves its mark Atopic dermatitis, a type of eczema that strikes in childhood, has a large impact on the quality of sufferers’ lives, a study commissioned by Menarini Asia-Pacific has found. Sixty-five per cent of 1,000 mothers of children with the condition said it affected their lives. Ninety-five per cent made at least one medical visit in the past year, and about one in three spent four hours a day or more caring for their children. Two-thirds spent US$794 in the past year dealing with the condition. “More than 50 per cent of patients will go on to develop asthma and allergic rhinitis if the disease is not managed properly,” says Professor Ellis Hon from Chinese University’s department of paediatrics. Childhood cancer not a barrier to pregnancy Survivors of childhood cancer have a roughly 50 per cent higher risk of infertility, but their chances of getting pregnant are still good, according to researchers at Dana-Farber/Boston Children’s Cancer and Blood Disorders Centre and Brigham and Women’s Hospital, in Boston. Nearly two-thirds of those who tried unsuccessfully to become pregnant for at least a year (the clinical definition for infertility) eventually conceived, on average, after six months. The study, published in The Lancet Oncology, involved 3,531 sexually active female survivors aged 18 to 39, and a control group of 1,366 female siblings of participants.
Another endocrinological of Hongkongers between study, by hypothesis rejects the ages of 18 and 64 University this, says Taubes. are overweight College The hypothesis is London based on two published in distinct ideas, the March in International first dating back to Journal of Obesity, found a 1923 by Wilhelm Falta, a student of Von Noorden and a pioneer of strong genetic component to childhood obesity, supporting the science of endocrinology. the hypothesis that children of Falta believed that the hormone obese parents are most at risk of insulin was driving obesity. becoming obese. Previous The second idea, based on research has shown that obesity the concept of lipophilia, or runs in families, with heritability “love of fat”, was proposed in 1908 by Gustav von Bergmann, a estimates at over 50 per cent. Obesity evolved into an German authority on internal eating disorder in the late 1960s medicine, and then taken up by Julius Bauer, who did pioneering and 1970s, Taubes says. Lab work on endocrinology, genetics researchers focused – and still do – on identifying why we eat too and chronic disease at the much, rather than why we store University of Vienna. too much fat. Observing that fat deposition “What makes this transition was not uniform throughout so jarring in retrospect is that it the body, Von Bergmann coincided with the identification proposed that people who are of the hormone insulin in the constitutionally predisposed to early 1960s as the primary fatten had adipose tissue that regular of fat accumulation in was more lipophilic than that of constitutionally lean individuals. fat cells,” he says. “Had Falta’s ideas and the lipophilia New research supports this hypothesis survived the second idea of a metabolic link with world war, this discovery would obesity. In a study published in have served to bring these two January in Nature Medicine, an hypotheses together. international team of “Because serum insulin researchers led by the Joslin levels are effectively driven Diabetes Centre - Harvard by the carbohydrate content of Medical School in Boston the diet, this hypothesis would suggest that obesity is the result implicate refined, high of an alteration in the processes glycaemic grains and sugars as that regulate food absorption the environmental triggers of and energy production. This obesity. They would be alteration tips the balance considered uniquely fattening … towards excessive storage of fat. because they trigger a hormonal The scientists observed that response that drives the blocking the expression of a partitioning of fuel consumed certain gene in mice protects them against obesity and insulin into storage as fat.” Not all calories are created resistance. The gene was found equal. For example, with sugary to modulate fat storage by beverages, the metabolism of regulating energy expenditure fructose in the liver is believed to and lipolysis, the process which circumvent leptin signalling, transforms fat into lipids for the leading to excessive body’s energy consumption.
consumption of these drinks. Fructose metabolism may also induce insulin resistance, leading to raised insulin levels and trapping fat in fat cells. In 2009, the American Heart Association published a paper suggesting that excessive consumption of sugar is linked to several metabolic abnormalities and adverse health conditions. It stressed a limit of 100 calories a day from added sugar for a woman (six teaspoons) and 150 calories a day for a man (nine teaspoons). Since that publication, several studies have implicated sugar consumption with increasing rates of obesity and type-2 diabetes. A study by University of Guelph researchers presented in May at the Canadian Neuroscience Meeting showed that high fructose corn syrup, a common sweetener added in processed foods, can cause behavioural reactions in rats similar to those produced by drugs of abuse such as cocaine. The experts say this suggests that food addiction could explain, at least partly, the obesity epidemic. Highly processed carbohydrates were also implicated in a study published in the American Journal of Clinical Nutrition last month. A Boston Children’s Hospital research team found that having such foods caused an initial surge in blood sugar levels, followed by a steep crash hours later. This decrease in blood glucose was associated with excessive hunger and intense activation of the nucleus accumbens, a critical brain region involved in addictive behaviour. jeanette.wang@scmp.com