WEDNESDAY, Jan. 21 (HealthDay News) -- Scientists have located a group of cancer stem cells or "tumor-initiating cells" which, when targeted with a reprogrammed herpes virus, are prevented from turning malignant.

The finding bolsters the theory that cancer harbors its own secret cache of stem cells that are resistant to conventional therapies and responsible for tumor re-emergence.

Eliminating these malingerers could be key in the fight against certain cancers, such as neuroblastoma, which was the focus of this study.

"This research and this line of research in general is very exciting," added Dr. L. Gerard Toussaint III, an assistant professor of neuroscience and experimental therapeutics at Texas A&M Health Science Center College of Medicine and a neurosurgeon with the Texas Brain and Spine Institute in Bryan. "Their approach is to genetically engineer a virus that would only be turned on in the stem cell population."

This type of virus-against-cancer therapy may be the next generation of anti-cancer treatments, he said.

The study was published online Jan. 21 in the journal PLoS (Public Library of Science) One.

Neuroblastomas, which develop in the nerve tissue of the adrenal gland, neck, chest or spinal cord, account for 8 percent to 10 percent of childhood cancers, the report stated. Remission is common, but so is relapse, and long-term survival in high-risk cases is less than 50 percent.

"The cancer often responds to chemotherapy and more often than not will shrink but too often it comes back," explained Dr. Jeffrey Toretsky, an associate professor of oncology and pediatrics at Georgetown's Lombardi Comprehensive Cancer Center in Washington, D.C. "The promise is that they will be able to successfully create some agent, a virus, that would be able to get at the cells responsible for regrowth."

Experts have theorized that stubborn and apparently undetectable stem cells are left unscathed by existing treatments, linger in the body and eventually reform the tumor or cause the cancer to spread.

"They go into remission then we don't detect the disease at all for one, two, three years, and then it comes back," explained study senior author Dr. Timothy Cripe, professor of pediatrics at Cincinnati Children's Hospital Medical Center and the University of Cincinnati. "Stem cells would explain that. We need to understand those cells and target them."

"If cancers are being seeded by a few cells, they need to be the target. We have maxed-out therapy for cancers, in particular neuroblastoma. We need to identify something novel and different," he continued.

These researchers identified and then grew several lines of human neuroblastoma cells that seemed to have characteristics of neural stem cells -- meaning, among other things, that they could grow into different types of cells including tumors. The cells also carried the protein nestin, which is a marker for nerve stem cells and is also present in neuroblastoma cells.

When the stem cells were infected with a herpes simplex virus which specifically targets nestin, they did not form tumors over the next 60-day period. When infected with a different virus that does not target nestin, mice developed tumors within 40 days. Mice who were uninfected with either virus developed tumors within 30 days.

But, Cripe cautioned, "we used cell lines propagated in plastic dishes. [We need to know] how does that relate to cells in humans?"

More information

There's more on neuroblastomas at the U.S. National Cancer Institute.

TUESDAY, Jan. 20 (HealthDay News) -- A minimally invasive therapy that uses beads soaked with anti-cancer agents has been successful at halting liver tumors, according to new studies.

Transarterial chemoembolization (TACE) attacks liver tumors on two fronts. Microspheres, or beads, combined with cancer-killing chemotherapeutic agents are delivered to the blood vessel feeding the tumor. While the chemo attacks the cancer, the microspheres get stuck in the vessels and choke off the blood supply to the tumor -- a process called embolization.

While surgically removing a tumor is the most effective way to treat one, this is not an option for most liver cancer patients. In two out of three instances, the size or location of the liver cancer prevents surgery, or the tumor has grown into the blood vessels. Typically, only a quarter of people with liver cancer survive two years after diagnosis.

TACE holds promise, because the tumor, rather than the entire body, receives the chemotherapy directly. It is used to slow, not cure, the disease, but successful improvements in the beads and the procedure were expected to be presented in three separate trials this week at the annual International Symposium on Endovascular Therapy (ISET) in Hollywood, Fla.

In the first study, done at St. Joseph's Hospital and Medical Center in Tampa, Fla., 10 of 11 liver cancer patients given beads that released the chemo drug doxorubicin were alive two years after the procedure. Ten of the 13 people patients who had colorectal cancer that spread to the liver and were given the same treatment also were alive after two years.

The "LC Beads," as they were called, also did not cause systemic side effects.

"There is definitely a chance of cancer cure with this procedure beyond just palliation," Dr. Glenn Stambo, vascular and interventional radiologist at St. Joseph's, said in an ISET news release. "The more isolated the tumor and its blood vessel feeders, the better the chance for a complete cure."

An Italian study showed positive results with "HepaSphere" beads, which expand once stuck in the vessels to better block blood flow while also delivering chemo agents directly into the tumor. More than 86 percent of the 53 liver cancer patients in that trial showed a complete response to the therapy after six months.

"Patients who still had good liver function and who had tumors in only one lobe of the liver did better with this treatment," Dr. Maurizio Grosso, chairman of the department of radiology at Santa Croce and Carle Hospital in Cuneo, Italy, said in the same news release. "We're hopeful that treatment with HepaSphere will be an improvement over traditional chemoembolization."

Even without chemotherapy added to the beads, the embolization technique showed promise in a different Italian study. About half of 34 primary liver tumors shrunk within one month in patients given non-chemo "Embozene" microspheres alone. The other half showed no signs of tumor growth.

In a group of 16 tumors observed over the next six to 12 months, two completely disappeared, seven shrunk, two remained the same size, and five grew. Those that grew, though, were still small enough for additional localized treatments to be tried.

"One of the main benefits of Embozene microspheres is the precise, well-calibrated sizing, which match the small blood vessels that feed the tumors. The larger the particles used, the further away the embolization from the tumor and the less effective the treatment will be," Dr. Franco Orsi, chief of interventional radiology at the European Institute of Oncology in Italy, said in the same news release. "Moreover, embolization without drugs usually causes few or no post-treatment side effects, and patient can usually be discharged the next day."

More information

The U.S. National Cancer Institute has more about liver cancer.

MONDAY, Jan. 19 (HealthDay News) -- Survival disparities between white and black patients with early-stage lung cancer disappear when black patients receive optimal therapy, according to a U.S. study that included nearly 18,000 patients.

Surgery to remove a portion of the lung (pulmonary resection) provides the best chance of a cure for patients with early-stage lung cancer.

"Black patients with early-stage lung cancer have lower five-year survival rates than white patients, and this difference in outcome has been attributed to lower rates of resection among black patients," wrote Dr. Farhood Farjah, of the University of Washington, Seattle, and colleagues. "Several potential factors underlying racial differences in the receipt of surgical therapy include differences in pulmonary function, access to care, refusal of surgery, beliefs about tumor spread on air exposure at the time of operation and the possibility of cure without surgery, distrust of the health care system and physicians, suboptimal patterns of patient and physician communication and health care system and provider biases."

Access to care is often considered the most important of the factors that affect racial disparities among lung cancer patients.

The study looked at nearly 18,000 patients (89 percent white and 6 percent black) who were diagnosed with lung cancer between 1992 and 2002 and recommended for pulmonary resection.

The researchers found that 69 percent of black patients had surgery, compared with 83 percent of white patients. Five-year survival rates were similar among both black and white patients who had surgery.

"Although these findings do not refute the likely roles of health care system and provider biases and patient characteristics as important causal factors underlying health disparities, the findings do suggest that other factors (i.e., distrust, perceptions and beliefs about lung cancer and its treatment and limited access to subspecialty care) may have a more dominant role in causing disparities than previously recognized," the study authors wrote.

"The implication of these findings is that interventions designed to narrow gaps in health care should target structured aspects of care, providers and patients and communities at risk for lung cancer and suboptimal care," the team added.

The researchers suggested that referral of all patients with potentially curable lung cancer for consideration of lung resection may help reduce racial disparities in survival.

The study was published in the January issue of the journal Archives of Surgery.

More information

The U.S. National Cancer Institute has more about lung cancer.

THURSDAY, Jan. 15 (HealthDay News) -- Colonoscopies performed by family doctors who are trained to conduct the procedure are safe, effective and meet standard quality guidelines for colon cancer screenings, new research reveals.

The finding is based on an analysis of 12 earlier studies conducted between 1966 and 2007, all of which focused specifically on the outcomes of colonoscopies performed by primary-care physicians -- as opposed to gastrointestinal specialists.

Noting that the nation's approximately 12,000 board-certified gastroenterologists are not sufficient in number to meet the ideal screening needs of the country's third most common cancer, the authors said that the findings should encourage a "fundamental role" for properly trained primary-care physicians -- particularly in rural areas -- as part of an effort to broaden access to colonoscopies.

"But I want to emphasize that this doesn't apply to all primary-care physicians in general," cautioned study author Dr. Thad Wilkins, from the department of family medicine at the Medical College of Georgia, in Augusta. "Our study is only evaluating the outcomes of colonoscopies performed by those doctors who are trained and competent in performing a colonoscopy, and that amounts to about 5 percent of all primary-care physicians. But among those that are trained, the results are comparable to those of specialists."

Wilkins and his colleagues reported their observations in the January/February edition of the Annals of Family Medicine.

Dr. Durado Brooks, director of colorectal cancer for the American Cancer Society, expressed little surprise with the findings, but advised patients to screen their physicians carefully.

"Most people who finish medical school would be widely capable of doing any number of procedures in a high-quality fashion if they have the appropriate training," he said. "So that's the key. Training."

"That means that on a basic level, you want to know if there is a quality monitoring system in place at the facility in which the primary-care physician practices," Brooks suggested. "And what sort of formal training your doctor had, and how many of these procedures have he or she performed in their past, and how often have they performed them recently. These are the important questions."

In the study, the researchers pointed out that colorectal cancer is currently the second leading cause of cancer death in the United States. They further noted that, despite the fact that less than a third of eligible patients now avail themselves of colonoscopies, the demand for such screenings is nonetheless growing fast.

To control for screening quality, the American Society of Gastrointestinal Endoscopists and the American College of Gastroenterology have recommended standards for methodology and detection sensitivity.

The 12 studies Wilkins and his team reviewed included slightly more than 12,000 colonoscopy patients, evenly split between men and women, with an average patient age of 59. Most of the screenings in the studies were performed by family physicians.

No one in the pool of patients died as a result of a colonoscopy, the authors observed, and just seven patients experienced either bleeding or colonic perforation complications. This complication frequency falls within standard guidelines, the researchers noted.

In just over 89 percent of screenings, the physicians were able to successfully conduct a proper and full rectum to cecum examination, in which the screening physician uses the telescopic device (colonoscope) to examine the entire colon.

Screening recommendations suggest that 90 percent to 95 percent of colonoscopies should meet this objective.

In that regard, the researcher noted that most colonoscopies now involve conscious sedation, and that when reviewing only those types of screenings, the rate actually went up to 90.5 percent.

And with respect to adequate spotting of benign or precancerous tumor growths known as adenomas, Wilkins and his colleagues found that the detection rate was nearly 30 percent -- again, well within recommended standards.

The researchers therefore concluded that colonoscopies performed by primary-care physicians are indeed safe and effective, so long as the physician is trained to conduct such screenings.

"Patients should simply ask their general practitioner if they are trained in colonoscopies," Wilkins advised. "And ask them, if so, how many they perform annually, the way you should and would when considering a doctor for any type of surgery or procedure."

On another note, other studies published in the same journal highlighted positive and negative findings, respectively, with regards to a different form of colon cancer screening known as the home fecal occult blood test (FOBT).

Long recommended as an effective annual method for initial colorectal cancer screening, one study led by Dr. Michael B. Potter, from the department of family and community medicine at the University of California, San Francisco, found that FOBT screening rates go up dramatically -- by almost 30 percent -- if the option is offered to patients while attending an annual flu shot clinic.

On the other hand, a second study led by Dr Masahito Jimbo, of the department of family medicine at the University of Michigan, suggested that a significant number of primary-care physicians fail to encourage their patients to adhere to guidelines that advise those who receive a positive FOBT result to undergo more rigorous follow-up screenings, such as a colonoscopy. Jimbo and his team called for colorectal screening programs to include specific physician guidance instruction as to when to prescribe additional evaluations.

More information

For more on colon cancer screening guidelines, visit the American Cancer Society  .