When reviewing research trials that are based upon observing a population of people in order to determine the incidence of certain diseases, I generally take great care to mention the inherent limitations of such epidemiological studies. This is particularly important in those studies that rely upon the study participants to recall their intake of certain foods and so-called nutritional supplements. Research studies such as these suffer from several potential sources of bias, including inaccurate information provided by study participants and bias on the part of the people who design and conduct such studies. I was, therefore, very pleased to review a new study just published in the Journal of the American Medical Association which looked at this very issue.
The authors of this study took, as their starting point, large, high quality prospective, randomized clinical trials that have convincingly shown that: (1) Vitamin E supplements do not appear to protect against cardiovascular disease; (2) beta-carotene does not appear to reduce the risk of cancer; and (3) estrogen hormone supplementation does not appear to protect against Alzheimer’s disease. The study’s authors then extensively searched the medical literature for references to older epidemiological studies that preceded these modern randomized clinical trials, and that had previously suggested the possibility that these vitamin and hormone supplements possessed disease-preventing effects. The results of this analysis revealed that numerous recently-published clinical studies still continued to cite the “favorable” results of earlier and less powerful epidemiological studies over the less favorable results of the more powerful and recent randomized controlled clinical research trials. Indeed, when looking at the medical literature in 2005 and 2006, the authors found that between 50% and 63% of the research papers published on Vitamin E, beta-carotene and estrogen still referenced the older and less powerful epidemiological studies (and their more favorable conclusions), rather than the more recent randomized controlled trials.
The results of this important study reveal what many of us in biomedical research already know: Long after early epidemiological studies have been debunked by high quality randomized clinical trials, the weaker—but more favorable—conclusions of the earlier studies continue to be preferentially cited by authors of newly published clinical research studies.
CARBON NANOTUBES & RADIOFREQUENCY: A NEW WAY TO FIGHT CANCER?
An intriguing new paper from the journal Cancer suggests a completely novel way to kill cancerous tumors without resorting to surgery, chemotherapy or radiation therapy. Recent research into the properties of carbon nanotubes have yielded some rather surprising results, and suggest that there may be novel clinical applications for these amazing structures. Carbon nanotubes are constructed from miniscule sheets of carbon, one-atom thick, that are then folded into tubular structures. These impossibly tiny cylinders are extremely efficient in conducting heat. What is particularly novel about the use of nanotubes in this study is that the study was based upon recent observations that the application of radio waves (radiofrequency) to carbon nanotubes results in tremendous heat generation in and around the tiny little tubes.
In this first part of this study, carbon nanotubes were placed into laboratory culture dishes in which human cancer cells were growing. Radiofrequency energy was then directed at these cell cultures, causing the cancer cells to die. In the very elegant second part of the study, liver tumors in rabbits were directly injected with nanotubes, and a non-invasive radiofrequency signal was then beamed through the skin, and focused upon the liver tumors. These tumors were then surgically removed 48 hours later and evaluated under a microscope. The results of this study showed that the liver tumors were completely destroyed by this treatment.
I find this research study extremely fascinating as a cancer surgeon. Currently, we use radiofrequency energy, applied directly into the tumor with a needle-like electrode, to “ablate” liver tumors that cannot otherwise be safely removed by surgery. However, radiofrequency ablation, or RFA, still requires a considerable amount of invasive surgery in order to accurately apply the radiofrequency energy directly into the tumor. As with recent studies looking at the use of high-frequency ultrasound, or HIFU, to non-invasively kill tumors inside the body, this new study of carbon nanotubes and radiofrequency offers the possibility that otherwise unresectable malignant tumors might, someday, be destroyed by passing radio waves thought the body after injecting carbon nanotubes inside the tumor itself.
OBESITY DURING CHILDHOOD & THE RISK OF HEART DISEASE IN ADULTHOOD
now, everyone knows that we are facing a global pandemic of obesity
that, increasingly, is affecting children as well as adults.
There is abundant clinical evidence that adult-onset obesity is
associated with a variety of life-threatening ailments, including high
blood pressure, diabetes, and heart disease.
A new study from Denmark has evaluated the impact of childhood obesity
on the risk of subsequent heart disease during adulthood, and the news
is not good.
This new study, just published in the New England Journal of Medicine, evaluated a public health database containing height and weight information on more than 276,000 schoolchildren between the ages of 7 and 13. Using other public health databases for adults, the researchers were able to identify 10,235 men and 4,318 women for whom childhood height and weight data was available within the larger schoolchildren’s database.
Interestingly, although increasing obesity (as measured by body-mass index calculations) among these children translated into an increased risk of developing heart disease later, as an adult, there was a significant gender-based difference noted as well. For the boys, increasing obesity during the interval between 7 and 13 years of age was associated with a progressively increasing risk of heart disease during adulthood, while the peak years during which obesity predicted an increased likelihood of adult-onset heart disease for girls was between ages 10 and 13. The heavier the children became, the greater their risk of heart disease later in life, during adulthood. The authors of this study note that these findings suggest that intervening during the gender-specific intervals identified in this study might significantly reduce the subsequent onset of coronary artery disease in obese boys and girls.
Disclaimer: As always, my advice to
readers is to seek the advice of your physician before
making any significant changes in medications, diet,
or level of physical activity
Robert Wascher is an oncologic surgeon, professor of surgery, and a
widely published author.
He is the Director of the Division of Surgical Oncology at Newark Beth
Israel Medical Center.
Send your feedback to Dr. Wascher at firstname.lastname@example.org
Copyright 2007. Robert A. Wascher, MD, FACS. All rights reserved.
Dr. Wascher's Archives:12-2-2007: Obesity & Risk of Cancer; Testosterone Level & Risk of Death; Drug Company Funding of Research & Results; Smoking & the Risk of Colon & Rectal Cancer