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Europeanen overschatten erfelijkheid kanker*
Veel Europeanen geloven in mythes ten aanzien van het ontstaan van kanker, terwijl het werkelijke belang van dieet en levensstijlfactoren volgens specialisten vaak onjuist wordt ingeschat. 
Dit zeggen specialisten tijdens de jaarlijkse bijeenkomst van de European Society for Medical Oncology (ESMO) in Wenen, waar verschillende nieuwe studies naar kankerpreventie en levensstijlinvloed werden gepresenteerd.
Volgens de Ierse oncoloog Derek Power, hoofdauteur van een van de gepresenteerde studies, heersen er nog veel mythes over het ontstaan van kanker. Zo zouden mensen denken dat een klap tegen de borst of een te strakke onderbroek risicoverhogende factoren zijn.
Erfelijkheid
Ook ten aanzien van erfelijkheid zitten veel mensen er naast. In het onderzoek van Power denkt de grootste groep respondenten dat 50 procent van kankers is veroorzaakt door een erfelijke factor, terwijl overgedragen genmutaties - afhankelijk van de specifieke vorm van kanker - slechts in 5 tot 8 procent van de gevallen de boosdoener is.
Dit misverstand heerst ook onder professionals in de gezondheidszorg, van wie maar liefst 90 procent denkt dat erfelijkheid 'het risico op kanker sterk beïnvloedt' - een onjuiste stelling, aldus de oncoloog.
Genetisch gemodificeerd
Ten aanzien van voeding is er volgens Power geen eensluidend bewijs dat genetisch gemodificeerde gewassen het risico verhogen, of dat biologisch geproduceerde etenswaren het risico verlagen. Ook andere vaakgerelateerde zaken, zoals het gebruik van mobiele telefoons of stress, zijn volgens hem geen grote risicofactoren.
Desondanks spelen dieet en andere levensstijlfactoren wel degelijk een zeer grote rol bij het ontstaan van kanker - waarschijnlijk is zo’n 90 tot 95 procent van de gevallen er aan te relateren. Dit terwijl 15 procent van de mensen volgens de Ierse onderzoeker denkt dat het risico op kanker tijdens een mensenleven überhaupt niet te beïnvloeden is.
Grotere misverstanden
Grote factoren, zoals overgewicht, roken en zonblootstelling, worden door veel Europeanen gebagatelliseerd, terwijl de verbanden hier juist nadrukkelijk zouden zijn. Hetzelfde geldt volgens Power voor alcoholconsumptie - waarover verkeerd zou worden gecommuniceerd.
Veel mensen zouden de hoogte van hun werkelijke alcoholinname verdoezelen, waardoor ze zich niet goed bewust zijn van de risicocategorie waarin ze zich bevinden. Tegelijk zouden gezondheidsdeskundigen beter moeten oppassen met het communiceren van het 'voordeel' van een matige inname van één tot twee glazen per dag.
Collectieve zorg
“Deze studies laten zien dat een groot deel van de Europeanen niet bepaald gecharmeerd is van het idee van eigen verantwoordelijkheid. In plaats van gedrag en levensstijl aan te passen, plaatsen zij liever de schuld bij factoren als erfelijkheid, of de rol van de samenleving”, zegt de Zwitserse professor Hans-Jörg Senn, hoofd van de faculteit kankerpreventie van ESMO.
Het is volgens Senn noodzakelijk om deze verkeerde denkbeelden te doorbreken, niet alleen om veel menselijk lijden te voorkomen, maar ook om in een vergrijzende samenleving de collectieve druk van zorgkosten en wegvallende arbeidskracht ten gevolge van stijgende kankercijfers te verlichten.
ESMO 2012 Press Release : Myths and misunderstandings hamper efforts to prevent cancer
“Overall, 90% people, including healthcare professionals, believed genetics ‘strongly’ increases risk,” Dr Power said. “More than one in four of the public believed that more than 50% of cancers are genetic. Incredibly 15% of people we surveyed believed lifetime risk of cancer is non-modifiable.” 
These misunderstandings must be tackled if cancer rates are to be reduced, he said.
“This misinformation needs to be addressed in health promotion campaigns, emphasizing that diet and lifestyle including smoking account for 90-95% of cancers,” he said. “Only about 5 to 8% of cancers, depending on cancer site, are due to an inherited gene.” 
When asked how to reduce risk, 27% of respondents said ‘detox’ diets could help and 64% would believe organic food is protective. Research has not shown either of these methods to be effective. Meanwhile, 28% were unaware that frozen vegetables and fruit are as good as fresh, and 41% were unaware of the link between red meat and cancer. Yet 86% knew that processed meat is a risk factor, and 46% were aware that too much salt also poses a risk. 
Finding new ways to communicate how obesity and its precursors increase a person's risk of cancer could boost the efficacy of efforts to motivate weight loss and prevent weight gain, Dr Power noted. Awareness also needs to be raised about the effects of alcohol. 
“We hope that by sharing these common misunderstandings and informing the public about proven cancer risks and prevention measures, we can help people to make lifestyle choices that will reduce their risk of developing the disease,” he said.
Moderate alcohol intake and cancer: the role of under-reporting
A large US cohort study in 129,987 persons suggests that the apparent increased risk of cancer among light-moderate drinkers is substantially due to underreporting of intake.
Although experts agree that heavy consumption of alcohol is related to increased risk of several cancer types, the role of light-to-moderate drinking is less clear, said Dr Arthur Klatsky of Kaiser Permanente Medical Care Program, Oakland, CA, USA. Some studies have suggested there is a connection, while others have found no link.
The results of the new analysis suggest that any apparent relationship between cancer risk and light-to-moderate drinking, meaning up to 2 standard sized drinks per day for men and one for women, may be largely an artifact of under-reporting—that is, lying about drinking amount. 
“If some heavy drinkers answer surveys saying that they only drink lightly, the effects of heavy drinking then appear to be related to light-to-moderate intake,” Dr Klatsky explained. “Our analysis inferentially supports this factor in our study population and it is probably applicable to most studies, as under-reporting of alcohol consumption is surely prevalent.” 
“There are plenty of reasons why people need to avoid heavy drinking, but these do not generally apply to light drinking,” Dr Klatsky said. “All concerns about the risks of light drinking need to be balanced by the evidence that persons at risk of heart disease benefit from lighter alcohol drinking. This --with plenty of exceptions-- means most persons over 50.” 
Younger women at high risk of breast cancer, who will not see any cardiovascular benefits from alcohol for many decades, do not have this favorable balance of harm and benefit, Dr Klatsky noted.
Encouraging doctors to quit smoking is no easy task, Turkish researchers find
When doctors smoke, it makes it harder for them to encourage their patients to quit. That's one of the factors that encouraged Dr Fikri Icli and colleagues from Ankara University Medical School to try and reduce smoking rates among medical students at their institute.
In many parts of Europe, smoking is common among doctors, Dr Icli notes. “The highest prevalence rates among male medical students in Europe were reported from Greece (41%) and Spain (42%).” 
In their study of 215 Ankara University medical students, Dr Icli's group found that 29.5% of male students and 22.6% of female students smoked. At the time of the initial survey, 60% said they only took up smoking once they entered medical school, and smoking rates tended to increase between the year of entry to medical school and the final year. 
“Once they start smoking, it is difficult to quit. Therefore the best way to fight against smoking among physicians is the prevention of starting smoking,” Dr Icli noted. 
Between 2007 and 2012, the university implemented a series of programs aimed at stemming this increase. A Cigarette Fighting Group, composed of voluntary academic staff, nurses, students, psychologists and a social worker, was established including regular monthly meetings, “smoking or health” lectures and annual symposia. 
By 2012, surveys showed that total smoking rates dropped 11%, and the smoking rate for 6th-grade students dropped from 35% in 2007 to 8.8%. On the other hand, although the university administration established a smoking cessation clinic for students, quitter rate didn't increase from 2007 to 2012.
That means that the success in cutting the smoking rate among medical students was mostly due to prevention of starting smoking after entry to medical school, Dr Icli said. 
“Increasing awareness of medical students related to the threat of smoking on health in the community, recognition of their non-smoking physician role-models and their potential role in cessation programs probably helps to counteract the influences to start smoking.”
 (Oktober 2012)

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