New technology pinpoints genetic differences between cancer and non-cancer patients

If this technology becomes commercially available, some persons may get discriminated against

 K S Parthasarathy

Genetic differences between cancer and non cancer patients

A group of researchers led by scientists from the Virginia Bioinformatics Institute (VBI) at Virginia Tech have developed a new technology that detects distinct genetic changes differentiating cancer patients from healthy individuals and could serve as a future cancer predisposition test.
The multidisciplinary team, which includes researchers from the University of Texas Southwestern Medical Center, has created a design for a new DNA microarray that allows them to measure the two million microsatellites (short, repetitive DNA sequences) found within the human genome using 300,000 probes.
Microsatellites, which tend to vary greatly among individuals and have traditionally been used in forensics and paternity tests, are also used to uncover information related to a number of other genetic diseases such as Fragile-X or Huntington's disease. This advancement aided the discovery of a unique pattern of microsatellite variation in breast cancer patients that were not present in the DNA of patients who are cancer-free. Through their evaluation of global changes in the genome, the researchers determined that this pattern change alludes to a new mechanism disrupting the genome in cancer patients and may represent a new breast cancer risk biomarker. The results of the work will be featured in an upcoming edition of the journal Genes, Chromosomes and Cancer. The study is available online (http://www.ncbi.nlm.nih.gov/pubmed/21240973).
"We have now arrived at a new biomarker – an indicator that could be used to evaluate the amount of risk that you have for developing cancer in the future," explained Harold "Skip" Garner, VBI executive director who leads the institute's Medical Informatics and Systems Division (http://bit.ly/g280kb). "This is part of an effort to understand their (microsatellite) role in the genome and then proceed on directly towards something that is of utility in the clinic. What just came out in our paper is a description of the technology that allows us to very quickly and efficiently and inexpensively measure these two million places using a uniquely designed microarray… It's the pattern on that microarray that provides us the information we need."
Watch a video of Garner discussing the research and its implications (http://www.youtube.com/watch?v=I0BOq5b5HnM).
Only a small percentage of microsatellites have been linked to cancer and other diseases because there hasn't been an effective method available for evaluating large numbers of these sequences. This technology is enabling scientists to understand the role of these understudied parts of our genome for the first time and may help explain the difference between the known genetic components in disease and those that have been explained by genomic studies. This tool can be used to identify and better understand genetic changes in many different types of cancer with the potential to serve as a universal cancer biomarker. It has already been instrumental in the discovery of a new biomarker (http://bit.ly/gPcJkC) in the estrogen-related receptor gamma (ERR-γ) gene, which indicates an individual's increased risk for breast cancer. The group is now pursuing a number of these cancer predisposition risk markers in colon, lung, and other cancers.

###

Smoking during radiation treatments reduces chance of overall survival

 A message to smokers who continue smoking during radiation treatment of cancer

Smoking during radiation treatments reduces chance of overall survival

Smokers who continue to smoke while undergoing radiation treatments for head and neck cancer fare significantly worse than those who quit smoking before therapy, according to a study in the February issue of the International Journal of Radiation Oncology•Biology•Physics, an official journal of the American Society for Radiation Oncology (ASTRO).

Although the association between tobacco smoking and head and neck cancers has long been established, there had been little data until now showing whether continued smoking during treatment affects prognosis.

"I've always told patients, 'You should really stop smoking,' but I had no tangible evidence to use to convince them that they would be worse off if they continued to smoke," Allen Chen, M.D., lead author of the study and residency training program director at the University of California, Davis, School of Medicine in Sacramento, Calif., said. "I wanted concrete data to see if smoking was detrimental in terms of curability, overall survival and tolerability of treatment. We showed continued smoking contributed to negative outcomes with regard to all of those."

Chen and colleagues reviewed medical records of 101 patients with newly diagnosed squamous cell carcinoma of the head and neck who continued to smoke during radiation therapy and matched those patients to others who had quit prior to starting radiation therapy for their head and neck cancers. Matching was based on primary disease site, gender, smoking duration, stage of disease, radiation dose, other treatment (surgery and chemotherapy) and date of initiation of radiation therapy.

The researchers found that 55 percent of patients who had quit smoking prior to treatment were still alive five years later, compared with 23 percent of those who continued to smoke. The poorer outcomes for persistent smokers were reported for both patients who had surgery prior to radiation therapy and patients who had radiation alone. Similarly, Chen and his colleagues found that 53 of the patients who still smoked experienced disease recurrence, compared to 40 patients in the control group. Active smokers also experienced more complications of treatment, such as scar tissue development, hoarseness and difficulties with food intake.

Chen said additional research will be needed to explain these differences in outcomes for patients with head and neck cancers. One theory suggests that smoking deprives the body of much needed oxygen.

"Radiation therapy requires oxygenation for the production of free radicals, which attack cancer cells," he said.

He also emphasized that their findings are based on an observational study, which does not establish a cause-effect relationship between smoking during radiation therapy and poorer outcomes. For instance, they were unable to determine with certainty the actual cause of death of each patient, and active smokers may be at higher risk of death from other medical problems such as heart disease, stroke and diabetes.

"Patients unable to quit may also have non-cancer-related medical and psychosocial problems that could possible contribute to inferior survival," Chen said.

"Those who continue to smoke even after a diagnosis of head and neck cancer are likely to be at higher risk for alcohol abuse, have less social support and have lifestyles associated with high-risk health behaviors. A diagnosis of cancer is emotionally devastating, and a lot of patients are reluctant to entertain the idea of smoking cessation. Many patients can't or won't connect the dots, and unfortunately, our data is showing that by continuing to smoke, they are more likely to gamble away the possibility of cure."

###

ASTRO is the largest radiation oncology society in the world, with more than 10,000 members who specialize in treating patients with radiation therapies. As the leading organization in radiation oncology, biology and physics, the Society is dedicated to improving patient care through education, clinical practice, advancement of science and advocacy. For more information on radiation therapy, visit www.rtanswers.org. To learn more about ASTRO, visit www.astro.org.

 

Radiation risks to women undergoing cardiac computed tomography (CT) angiography

Researchers from the department of radiology and radiological sciences, medical university of South Carolina, estimate that the average cancer induction risk for in a cohort of 100 patients (60 men and 40 women) in their study was 0.13 percent. According to them, the radiation risk to women is 2,6 times more than that in men. 

The latest issue of the American Journal of Roentgenology (AJR 2011; 196:W159-W165) published the results