CT scans may raise cancer risk

The hazards of radiation from CT scans was highlighted by some articles published in this week's Archives of Internal Medicine.


One study found that the number of CT scans has increased dramatically in recent years in the US putting patients at the risk of developing radiation-induced cancer. They estimated that the CT scans performed in 2007 will eventually cause 29,000 cancers and 15,000 death.


Another study found that radiation doses from common diagnostic CT scans are much higher than we previously thought and the amount of radiation varies wildly and much greater than is considered acceptable. Based on their findings, they estimated that at the age of 40, 1 in 270 women who get CT scan of the heart will develop cancer and 1 in 600 men. 1 in 8,100 women who get scans of the head and 1 in 11,080 men.


In an accompanying editorial, the author asked are such risks justified and concluded that "to avoid unnecessarily increasing cancer incidence in future years, every clinician must carefully assess the expected benefits of each CT scan and fully inform his or her patients of the known risks of radiation". Greater standardization across institutions is also needed.


Source: ( both f/t via Athens )
"Radiation Dose Associated With Common Computed Tomography Examinations and the Associated Lifetime Attributable Risk of Cancer" Arch Intern Med. 2009;169(22):2078-2086


"Cancer Risks and Radiation Exposure From Computed Tomographic Scans: How Can We Be Sure That the Benefits Outweigh the Risks?" Arch Intern Med 2009;169:2049-2050.

Folic acid and B vitamins do not affect cancer risk

Folic acid and B vitamins are thought to have an important role in cancer prevention, but a study published in JAMA found that these supplements had no significant effects on overall cancer risk.

More than 5000 women health professionals, aged 42 or older, enrolled in a RCT designed to evaluate the effects of folic acid and B vitamins on cancer risk in women with high risk cardiovascular disease. They were randomly assigned to receive a daily combination of folic acid and B vitamin or a placebo for 7.3 years.

Researchers found that the supplement group had similar risk of developing cancer or death and there was a significant reduced risk of cancer in women aged 65 or older at study entry. The authors said "if the findings is real and substantiated, the results may have public health signficance because the incidence rates of cancer are high in elderly perosns...."

Source: Effect of Combined Folic Acid, Vitamin B6, and Vitamin B12 on Cancer Risk in Women. JAMA, 2008; 300 (17): 2012-2021 ( f/t via Athens)

Regular exercises reduce cancer death risk in men

Newspapers reported on a prospective cohort study of more than 40,000 Swedish men that found those who exercised moderately for at least 60 minutes a day reduced their risk of cancer, also in men who have cancer, 30 minutes a day of moderate exercise improved their chances of survival by 33%.

The researchers said the findings ‘may have major public health implications in the prevention and treatment of malignancies’ but the results require confirmation.

Critics say the study did not take into account the effect of diet that can influence their risk of cancer and it is possible that the men who exercised more also had healthier diets.

Source: "Association of physical activity with cancer incidence, mortality, and survival: a population-based study of men" British Journal of Cancer (2008) 98, 1864-1869.

Gum disease link to cancer risk

The BBC reports - Men with a history of periodontal (gum) disease were 14% more likely to develop cancer than those without. This is based on a prospective cohort study that analysed data for more than 48,000 male health professionals who had not had cancer prior to 1986 and who responded to questionnaires about periodontal disease.


Researchers concluded that "periodontal disease is associated with a small, but significant, increase in overall cancer risk" and that this increase in risk exists in men who had never smoked, but they said that "any recommendations for prevention of cancer based on these findings are premature" and further studies are needed to clarify whether periodontal disease itself causes the increase in cancer or whether it indicates some other factors.


Critics say the study included only male professionals, the results may not apply to other groups of people.


Source: "Periodontal disease, tooth loss, and cancer risk in male health professionals: a prospective cohort study." Lancet Oncology 2008; May 6 [Epub ahead of print]

Cancer risk continues after HRT stopped

The Women's Health Initiative (WHI) trial of HRT in 2002 stopped early because cancer risks and heart disease were found while taking the treatment.


The Times reported that the same team conducted a follow-up study to 2005 monitoring 15,730 women with an average age of 63, originally included in the trial. The women were randomised to take either the combined HRT pill or placebo. The study found that three years after stopping the treatment, the risk of breast cancer was significantly higher than the placebo group, but other risks such as blood clots and strokes, return to normal after the women stopped taking the pills.


The research team pointed out that the findings should be interpreted with caution and suggested that to reduce the cancer risks, HRT should be used at the minimum effective dose and for the shortest possible time. The study was published in JAMA.

Source: "Health Risks and Benefits 3 Years After Stopping Randomized Treatment With Estrogen and Progestin" - JAMA. 2008;299(9):1036-1045 ( full text via Athens)

Vitamin supplements or no supplements?

The Telegraph reported on 15 Feb that a scientist who spoke at the annual conference of the American Association for the Advancement claimed that taking multivitamin could reduce cancer risk.

However, on 26 Feb, it reported that the World Cancer Research Fund (WCRF) warned that vitamin supplements may do more harm than good and urged people to eat healthy diet raher than rely on supplements. This is contradicts the findings of a new report from the Copenhagen University Hospital that found betacarotene, vitamin A, and vitamin E may increase mortality. The results were based on 47 trials involving more than 180,000 people. They found that antioxidant supplements increased mortality by 5 per cent.

The news has attracted a lot of interesting comments from the public.

CT scans raise cancer risk

A research article published in this week's NEJM raised serious concerns about the cancer risks associated with CT scans due to its widespread use in America.

CT sacns are increasingly used in America to diagnose medical problems in children as well as adults, they are needlessly exposed to dangerous radiation that raises the risk of cancer.

The authors said that "too many CT studies are being performed in US" and suggested ways to reduce overall radiation dose from CT including reducing dose in individual patients, using other options and reducing the number of prescribed CT studies.

Source : "Computed Tomography — An Increasing Source of Radiation Exposure" NEJM, Volume 357(22):2277-2284 ( free full text)

The more alcohol you drink, the higher bowel cancer risk

A Cancer Research UK study found that a large glass of wine or a pint of beer a day increases the risk by about 10 %.

The research shows that the more alcohol you drink, the greater your risk of developing bowel cancer. However, the authors said that people can reduce their risk of cancers by cutting down on alcohol. The findings are published in the International Journal of Cancer. (subscription needed)

More than 30,000 new cases of bowel cancer are diagnosed each year in the UK alone. The lifetime risk for bowel cancer is 1 in 20 for men and 1 in 18 for women.

Does high-veggie diet stop cancer return?

According to a study published last week, daily servings of fruits and vegetables does not increase breast cancer survival rates. The current results contradict previous findings that diet made a big difference in reducing breast cancer risk.

Breast cancer survivors were assigned to 2 groups : a control group that followed the FDA nutrition guidelines and an intervention group that was instructed to consume 8 servings of fruits and vegetables, plus 16 ounces of fresh vegetable juice and permitted to eat meat but consume no more than 20% of total calories from fat.

Some cancer experts said that the study was poorly designed and executed: participants self-reported their eating habbits, most did not reach the target of fat reduction and the participants already ate more fruit and vegetables than most Americans before the study started. Some experts said the conclusions were misleading fearing it would discourage breast cancer survivors from pursuing a healthy diet.

The study "Influence of a Diet Very High in Vegetables, Fruit, and Fiber and Low in Fat on Prognosis Following Treatment for Breast Cancer" was published in JAMA. 2007;298:289-298. Read the abstract.

Read the press release at ABC News.

Low cholesterol linked to cancer risk

Statins are the world's top-selling drugs in lowering cholesterol to reduce the risk of heart disease, but a new meta-analysis that examined more than 4o,ooo patient records in 23 different trials of statins found that low cholesterol increased cancer risk although the study did not show that the statin drugs themselves caused the cancer.

The reserachers said their findings support taking multiple medications rather than high-dose statins to minimize the side effects and emphasized that patients should continue their statins treatments. The study is published in the July 31, 2007 issue of the Journal of the American College of Cardiology (JACC) 2007, 50:419-420.

In an accompanying editorial, John C. LaRosa said "these current findings provide insufficient evidence that there is any problem with LDL lowering that outweighs its significant benefits on vascular disease." Read the press release.

CT scan may increase lifetime cancer risk

A 64-slice computed tomography coronary angiography (CTCA) is a type of high-tech scan that is used to evaluate heart disease, but there are little data on its associated cancer risk from the radiation exposure.

A group of researchers conducted a study to estimate the lifetime attributable risk (LAR) of cancer associated with standard radiation exposure from a single heart scan using 64-slice CT coronary angiography. They found that the risk varied widely and were the highest with women in their 20s compared with other adults and concluded that CTCA should be used cautiously, especially in young women, using the lowest effective dose of radiation.

The study "Estimating Risk of Cancer Associated With Radiation Exposure From 64-Slice Computed Tomography Coronary Angiography" is published in JAMA. 2007;298(3):317-323 .