February 2010

Studies Suggest Possible Link Between CT Scans And Cancer

By Brian McCurdy, Senior Editor

   In recent years, computed tomography (CT) has gained wider usage among podiatrists as a diagnostic tool. However, recently published studies in the Archives of Internal Medicine sound a warning about a potential link between CT scans and cancer.

   In the first study, researchers estimated that about 29,000 future cancers could be related to CT scans performed in 2007.

   In the second retrospective study, researchers assessed the 11 most common types of diagnostic CT studies performed on 1,119 consecutive adults in 2008. The overall median effective radiation doses ranged from 2 millisieverts (mSv) for a routine head CT scan to 31 mSv for a multiphase abdomen and pelvis CT scan, according to the study.

   Researchers also estimated that one in 270 women who underwent CT coronary angiography at age 40 will develop cancer from a CT scan in comparison with an estimated one in 8,100 women who had a routine head CT scan at the same age.

   The study authors conclude that radiation doses from CT scans may be higher and more variable than generally known. Accordingly, they emphasize the necessity of more standardization across institutions.

CT Scans In The Lower Extremity: What You Should Know

   How much radiation do patients get from a lower extremity CT scan? Molly Judge, DPM, notes that a CT from the hip to the toes is equivalent to a single view chest X-ray. She says when it comes to the lower extremity, CT in general provides a low radiation dose.

   Dr. Judge will use a CT scan for a patient with a bone problem involving complex fracture and dislocations. If the problem is more vague and there is generalized bone and joint pain, Dr. Judge will opt for a triphase bone scan to “localize the pathology” and will consider other imaging modalities once she has honed in on the location.

   Dr. Judge, a Fellow of the American College of Foot and Ankle Surgeons, says the radiation dose of the triphase bone scan is equivalent to a two-view chest X-ray.

    “We tend to use this scanning modality liberally to reduce radiation exposure while obtaining a very good screening tool to determine if another form of ancillary imaging is necessary,” explains Dr. Judge, who is a certified nuclear medicine technologist.

   Michelle Butterworth, DPM, agrees about the need for standardization of radiation levels. She concurs with Dr. Judge that lower extremity CT scans seem to have a lower risk.

    “If the scan will aid in your diagnosis and guide your treatment plan, I think the benefit of the scan outweighs the risk regardless of sex or age,” maintains Dr. Butterworth, a Fellow of the American College of Foot and Ankle Surgeons.

   Dr. Butterworth most often uses CT scans to evaluate trauma patients. She says the scans can be helpful in assessing ankle fractures, calcaneal fractures and Lisfranc’s fractures. She orders CT scans for most complex midfoot and hindfoot fractures as well as some forefoot fractures. Dr. Butterworth adds that pursuing 3D reconstructions can also help facilitate better evaluation of the fractures.

   Dr. Butterworth says the CT scan permits a better overall view of the fragmentation and alignment of the fractures with much greater detail than standard radiographs.

    “I cannot give you one instance where a podiatrist can go wrong with a CT scan unless he or she is completely off the mark about standard indications and what pathology it can educate the physician about,” notes Dr. Judge, who is in private practice in Toledo and Port Clinton, Ohio. “I would not have suspected that overuse would have been an issue in our specialty of medicine.”

Can Metformin Help Prevent Diabetes?

By Lauren Grant, Editorial Assistant

   As the number of adults with pre-diabetes continues to rise, it becomes increasingly crucial to identify preventive measures to help head off the development of diabetes. A recent study published in Diabetes Care validates the recommendation of an American Diabetes Association (ADA) consensus panel that metformin (Glucophage, Bristol-Myers Squibb) can be a viable modality for preventing the disease in those at risk.

   Researchers assessed risk factors in a total of 4,706 patients (without known diabetes) culled from three different surveys. The criteria for inclusion included the presence of impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and a variety of additional risk factors for diabetes.

   The study concluded that more than 96 percent of patients with both IFG and IGT met criteria established by the ADA to be considered for metformin treatment. After extrapolating their data, the authors estimated that approximately one in 12 U.S. adults has a combination of pre-diabetes and risk factors that may justify metformin therapy.

   David Armstrong, DPM, MD, PhD, is not surprised by the estimate of those with pre-diabetes. He says the data “may be an underestimation” of what he sees as the Director of the Southern Arizona Limb Salvage Alliance (SALSA) at the University of Arizona. Lawrence Lavery, DPM, also was not surprised by the results of the study.

    “Type 2 diabetes is a disease of obesity,” maintains Dr. Lavery, a Professor in the Department of Surgery at the Texas A&M Health Science Center College of Medicine. “Our nation is faced with an epidemic of obesity and therefore an epidemic of diabetes.”

   Dr. Armstrong feels that looking at family history is an important part of the process in identifying patients who may be at risk for diabetes.

    “A good history — particularly a family history — can help us identify a patient’s trajectory. When it comes to diabetes, the apple does not fall too far from the tree,” says Dr. Armstrong.

   Dr. Lavery says the criteria outlined in the study was established by a board of experts and sponsored by the ADA. He adds that the American College of Endocrinology has provided similar recommendations for pre-diabetes criteria and treatment.

   Dr. Armstrong notes that many of the patients he sees have already been diagnosed with diabetes and are trying to prevent amputations. Similarly, Dr. Lavery says most of the patients he sees are referred by primary care physicians seeking consultations. However, Dr. Lavery says the idea of DPMs referring patients they suspect of having pre-diabetes for preventative treatments is “really a new concept” that should be encouraged.

   Dr. Armstrong adds that metformin has the benefit of “decades of use, not only for diabetes but more recently for impaired glucose homeostasis.”

Study Cites Benefits Of Epidermal Growth Factors For DFUs

By Brian McCurdy, Senior Editor

   Various advanced treatment options have emerged for patients with higher-grade diabetic foot ulcers. A recent study in the International Wound Journal finds positive results in treating ulcers with intralesional injections of recombinant human epidermal growth factors (EGF).

   The study authors conducted a multicenter, double-blind, placebo-controlled, randomized trial of 149 patients with diabetic foot ulcers categorized at Wagner grade 3 or 4. Different patient groups received EGF at doses of 75 mg, EGF at doses of 25 mg or a placebo three times a week for eight weeks as well as standard wound care.

   The study notes the main endpoint of the study was granulation tissue covering greater than 50 percent of the ulcer at two weeks. Forty-four of 53 patients in the higher dosage EGF group achieved this endpoint in comparison to 34 out of 48 patients in the lower dosage EGF group and 19 of 48 patients in the control group.

   The researchers also found a faster time to complete response of three weeks in EGF patients in comparison to five weeks in the placebo group. The study notes mild adverse reactions and no severe drug-related reactions in those treated with EGF.

   Despite the study’s conclusions, one DPM is skeptical of using EGF to help treat diabetic foot ulcers. Gerit Mulder, DPM, notes “no known or supported advantage of using EGF to treat any grade of diabetic foot ulcers.”

   Platelet-derived growth factors (PDGF) are the only growth factors that have demonstrated significant benefit as far as treating diabetic foot ulcers, according to Dr. Mulder, a Professor of Surgery and Orthopedics in the Department of Surgery/Division of Trauma at the University of California San Diego.

   Dr. Mulder adds that he does not see evidence supporting expedited closure with EGF as compared to other therapies for diabetic foot ulcers.

In Brief

   Pluristem Therapeutics has announced interim results from its Phase I clinical trials utilizing the placenta derived cell therapy product, PLX-PAD, for the treatment of critical limb ischemia (CLI). Nine patients underwent treatment with the product and experienced no significant unfavorable effects, with data suggesting PLX-PAD is safe and effective, according to the company.

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