Tag Archives: brain cancer

Pontine Glioma

brain

Childhood cancer is ordinarily treatable. Although it can be scary when one’s child develops cancer, children’s resilience means cancers in children respond very well to treatment. The only exception is brain tumors, which, because it requires such precision to treat anything in the brain, are the riskiest for children. That includes a cancer of the brainstem called a pontine glioma, one of the most dangerous tumors to treat.

The brainstem is the part of the brain that controls essential function. It’s difficult to label any part of the brain the most important—the entire thing is important—but it is the brainstem in which dysfunction has the most inevitably noticeable and broadest, and widest ranging effects. The pons, where pontine glioma develops, is responsible for breathing.

Children who develop pontine glioma will have trouble walking, standing, and speaking, because the tumor affects parts of the brain that communicate with the arms and legs, as well as the speech areas. It also affects the facial muscles, making eye movement and swallowing difficult and causing one side of the face to droop. Children with this type of tumor may also have trouble closing their eyes all the way, and may have double vision. Pontine gliomas often grow rapidly, causing damage as they do.

It is not known what causes these tumors to develop. There is a type of fungal infection of the scalp that is ordinarily treated with radiation, and children who have had this radiation treatment are more prone to developing glioma of the brainstem, but not all cases can be traced to that source. In a recent study, researchers found that the genetic code of the tumor contains gene mutations that had not previously been linked to any form of cancer, and they say this may prove to be a useful diagnostic tool in the future.

Sadly, children diagnosed with pontine glioma are not expected to survive more than nine months. Fortunately, however, new treatments are being developed that could well save lives. Now that mutations linked with pontine glioma have been discovered, scientists are tracing the effects of those mutations, determining how they relate to tumor development, and finding ways to prevent tumors from developing and destroy them when they do.

Cytomegalovirus

As many as four in five American adults have been infected with a microbe called human cytomegalovirus. Infection rates climb in older populations: more than 90 percent of people over 80 have the virus. The good news is that having the virus doesn’t necessarily mean exhibiting any symptoms; the bad news is the virus is tenacious, and while a healthy immune system can suppress it, it never goes away. Moreover, it does show symptoms in babies, typically jaundice, low birth weight, enlarged spleen or liver, or a rash, though babies who are monitored seldom have serious problems due to cytomegalovirus later in life.

It’s a little more serious when it makes adults sick. People who have weakened immune systems, such as after bone marrow or organ transplants, can become very sick—sometimes fatally so—as a result of cytomegalovirus infection. Symptoms in adults include changes in behavior, blindness, coma, diarrhea, encephalitis, hepatitis, pneumonia, seizures, and digestive ulcers which sometimes bleed.

If you have these symptoms, or if you have reason to believe you’re infected and have either a compromised immune system or are pregnant, it’s important to see a doctor. Treatment is not needed—or even recommended—for people who are showing no symptoms and are not otherwise affected. A doctor who determines that treatment is needed can prescribe the antiviral drugs used to treat cytomegalovirus when it does pose a serious threat.

Another group of people who should be treated are patients with certain types of brain cancer. A recent study at The Ohio State University found that while cytomegalovirus does not cause cancer itself, it does impede the body’s defenses against tumors that are already established. This can actually help the cancer, called glioblastoma, to grow more rapidly.

The study’s authors suggest that the brain cancer reactivates the usually dormant virus, which in turn makes changes to the tumor that help it to grow and thrive. They say that in light of these findings, cytomegalovirus should be looked for and, if necessary, treated in cancer patients as well as babies and people with weakened immune systems.

Unusual Treatment For Brain Tumors

The disease poliomyelitis, often just called polio, which crippled millions of children until a vaccine was developed in the 1950s, is now being turned into something beneficial. The same inactivated virus used in the vaccine seems to also, when introduced into a type of brain tumor called glioblastoma multiforme, destroy the tumor from the inside. Researchers have discovered that cancer cells have receptors that turn out to invite poliovirus infection.

The poliovirus vaccine, invented by Jonas Salk, was first made available in 1955. It was the first major advance in combating poliomyelitis, which at the time affected tens of thousands of children annually—in fact, the worst polio outbreak in the United States occurred in 1952 and 1953, with twice the average number of cases in the latter year. Thanks to the vaccine, however, polio was almost entirely eradicated in the U.S. by 1985, and fewer than 300 cases were reported worldwide in 2012.

Glioblastoma accounts for more than half of all brain tumors, and affects almost 10,000 Americans. Though rare, it’s deadly, even with treatment; most patients receiving radiation therapy and chemotherapy nonetheless die of the condition in less than a year and a half. White or Asian people who are more than 50 years old are at the most risk, with slightly higher prevalence in men than in women. The cause is poorly understood, but links have been found with exposure to lead and to the industrial plastic polyvinyl chloride, and to the mosquito that spreads malaria.

Although radiation and chemotherapy have been of limited effectiveness, other treatments are available. Surgery is sometimes performed to remove the tumor, though this is, obviously, extremely risky. In addition, results are mixed, and the surgical option doesn’t always prevent the cancer from recurring. Some new treatments use targeted intravenous medication to focus on specific features of cancer cells, killing them. Researchers at Duke University have discovered that is somewhat how poliovirus functions as a cancer treatment. The treatment uses a form of the ancient disease specifically designed to be harmless to healthy human cells. The virus is introduced directly into the tumor, where it destroys the cancer from within while also triggering the immune system to attack it.

The Rare Disease Turcot Syndrome

The rare condition known as mismatch repair cancer syndrome, or Turcot syndrome, was first described in 1959 by Jacques Turcot, a French scientist. The syndrome results in tumors in the brain and central nervous system, as well as polyps and tumors in the colon. People with Turcot syndrome are at elevated risk for developing colorectal cancer. The disease occurs when a mutation in the genes that help repair flaws in DNA replication causes those genes to be ineffective.

Symptoms include:

  • Diarrhea
  • Abdominal pain
  • Weight loss
  • Cognitive difficulties as a result of the central nervous system effects
  • Behavioral changes caused by brain tumors

There are about fewer than 2,000 people with the condition in the United States.

Rare among genetic diseases, the mutation that causes Turcot is dominant, meaning there are no asymptomatic carriers, and children who have one parent with the disease have a 50 percent chance of having it themselves. The condition usually manifests during the teen years, but genetic testing can look for the mutations involved before that if someone may be at risk.

There is no cure for the condition, but genetic research is ongoing. The polyps can be surgically removed, but may be too numerous for this to be effective. Cancer screening is recommended, because Turcot patients are at elevated risk for colorectal cancer, and a brain tumor called glioblastoma.

Better Predicting Path of a Brain Tumor

The deadly brain tumor glioblastoma multiforme often strikes without warning. It’s also the fastest growing tumor originating in the brain, and can vary greatly between patients. That makes it difficult to track or predict, which in turn presents a major obstacle to treatment. Now a new look at the condition has found a surprisingly accurate model for finding patterns in the tumor’s growth and determining the efficacy of treatment: weather patterns. Researchers say GBM growth can be tracked in the same way storms are tracked, using similar computer models.

“Glioblastoma” means the tumor grows from the glial cells that protect, insulate, secure, and nourish the neurons in the brain. “Multiforme” refers to the fact that it presents in a variety of diverse forms. It is found more frequently in men then in women, and like many cancers it is more common in patients over 50. Although no sign of a general hereditary predisposition to GBM has been found, several genetic disorders, including neurofibromatosis, carry an increased risk of the condition. Certain kinds of chemical exposure seem to make the tumor more likely; some studies indicate a connection to PVC. Lead exposure also seems to be linked with the condition.

One study suggests that a phenomenon called genetic fusion may be connected to GBM. This is a type of mutation in which two genes that are unrelated but have segments that look similar link up with each other, like pieces of a jigsaw puzzle that match in shape but not color. When this happens, neither gene can be properly expressed, and the entire affected chromosome is disrupted. One particular merger has been linked with three percent of all GBM cases, and it is believed that others may be collectively responsible for a substantial portion.

The median survival rate of GBM is just 15 months after diagnosis, but that number is lengthening. In the past five years, the number of patients who survived more than two years tripled, thanks in part to improved treatments. Two common treatments are surgery and radiation therapy, but radiation carries the risk of itself causing further tumors, and surgery is dangerous. The storm forecasting model recently developed helps measure the effectiveness of these treatments. Since tumors, like storms, are chaotic systems but nonetheless follow known patterns, doctors can use similar mathematical models to predict how the tumor would have grown without intervention, and compare the results of the intervention to that prediction.

New Hope for Gliomas

Earlier this month, researchers at the University of Southern California announced an important discovery. The scientists found a simple way to make certain kinds of tumors much more vulnerable to radiation therapy, in turn making treatment easier and more effective.

Glioblastoma multiforme, a kind of glioma, is the most common type of brain tumor. Half of all patients diagnosed with glioma survive less than two years. GBM strikes in star-shaped cells called astrocytes, and the tumors are marked by rapid growth. It is the most invasive type of glioma, generally spreading to different parts of the brain and sometimes even to other parts of the body.

Unfortunately, when gliomas appear at multiple locations, the already low long-term survival rates plummet. In one study, patients with multisite tumors survived an average of just six months. Indeed, sometimes the prognosis is so brief that state-of-the-art treatments cannot be used because there’s simply no time. There’s some evidence that these multisite tumors are resistant to treatment; it seems that the mechanisms by which they invade multiple sites also protect the tumors from medical attack.

Treatment for glioma usually starts with surgery, to remove the major portion of the tumor. In some cases, surgery is either deemed unnecessary or regarded as too dangerous. Whether or not surgery is indicated, radiation treatments and chemotherapy are used to shrink and eliminate tumors. The drug temozolomide has been used for almost 15 years in conjunction with radiation to treat several kinds of cancer, including glioma, with some success and with fewer adverse effects than older therapies.

One thing that makes radiation therapy more effective, the UC researchers discovered, is a brief period of controlled fasting immediately before the radiation. Mice with brain tumors who were not fed up to 48 hours before therapeutic doses of radiation had more than double the survival rate of mice fed normally. Studies have not been undertaken in humans but the researchers have suggested that it may be helpful as a last-ditch effort to boost the effectiveness of treatment.

Brain Cancer Vaccine

One of the biggest dangers for cancer patients is relapse. In many cases, even when cancer is cured there’s a risk of it coming back, requiring the patient to go through the whole treatment ordeal again. Indeed, in many cases it comes back resistant to treatment.

Now researchers have created a way to help keep some cancers from coming back. At a conference in Miami, oncologic researchers announced success in trials of a process to create a cancer vaccine from tumors.

Glioblastoma multiforme, the specific kind of brain cancer for which the process was demonstrated to be effective, is the most common cancer affecting the brain, as well as the most aggressive. It kills thousands of Americans each year.

Vaccination has proven difficult, because each incidence—each tumor—is biologically unique. That means a general solution is unlikely to be effective, because no two patients’ tumors are alike. The scientists have now found a way to use the tumor tissue to create a vaccine against each person’s specific strain.

The next step is to test the treatment in combination with the current standard therapy. The hope is that the combination will be more effective than either alone.