Metastases are often more dangerous than the primary tumor that gives rise to them. They are responsible for 90% of all cancer deaths. Here are the most important facts on these deadly ‘sleeper’ tumors.
Image: Anna Berghoff, DKFZ
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Created by cells released by the primary tumor that have been transported to other organs or body parts, metastases – secondary cancer growths that spread through the body – are often viewed as its ‘deadly offspring'. At these secondary sites, the cells proliferate and grow into dangerous metastatic tumors.
"Usually cells have their dedicated place in the body – they don't migrate,” explains Susanne Weg-Remers from the German Cancer Research Center in Heidelberg. "But malignant cells from solid tumors can in some instances cross anatomical boundaries. Those malignant cells then invade other environs and destroy the surrounding tissue.”
When the malignant cells enter the bloodstream or lymphatic system, they are transported throughout the body, and can dock onto and enter tissue in other areas. Once there, they establish themselves and begin to divide, eventually turning into metastases. Those metastatic tumors are no longer localized, meaning they can spread elsewhere in the body and can no longer be controlled.
Under what conditions do metastases form?
Cancer begins when the DNA in previously healthy cells changes during the course of life. That gives rise to cells with new characteristics. For example, growth behavior can change. Cells can begin to divide in an uncontrolled way, and no longer heed the body's signals to stop.
To host a metastasis, a particular location in the body has to fulfil a range of conditions. The malignant cells need access to the circulatory system. "The cells have to stimulate the growth of blood vessels in the area. These have to penetrate the newly-forming tumor to ensure it's hooked up to the bloodstream,” says Weg-Remers. The vessels supply the forming metastasis with blood that carries oxygen and nutrients, allowing the cells in it to multiply.
A migrating cancer cellImage: DKFZ
Types of cancer that frequently metastasize
Lung cancer is one type of carcinoma that has frequently already metastasized by the time an initial diagnosis is confirmed. Pancreatic cancer, liver cancer and bile duct cancer are also very aggressive forms of the disease. One big problem with these conditions is that sufferers rarely have any physical complaints until the cancer has progressed significantly. "They're often only recognized when the metastases have already formed. At that point, the cancer is no longer curable,” explains Weg-Remers.
Cancer treatments are most successful when the tumor is confined to a single location and surgeons can remove it without causing potentially life-threatening damage. That is what makes brain tumors a challenge to treat. While they are usually confined to the brain, complete surgical removal is often difficult.
Brain cancer – a special case
Primary brain tumors grow directly out of the organ's tissue or the surrounding connective tissue, and only rarely metastasize. When they do, the metastases appear in the areas filled with cerebrospinal fluid, a liquid that surrounds and cushions the brain.
Even though they so seldom metastasize, brain tumors still often prove deadly when vital functions in the brain are affected. Many brain cancers are also secondary tumors, meaning cancers that have spread from other parts of the body. "The brain apparently offers good docking opportunities for metastases,” says Weg-Remers. "The molecular mechanisms that play a role in the process are the subject of ongoing studies.”
Often, metastases form in the lungs Image: picture-alliance/Okapia
Metastases and their preferred organs
Although brain tumors rarely metastasize, other types of cancer – such as lung cancer – can spread to the brain. Breast cancer on the other hand often spreads to nearby lymph nodes. When breast cancer metastasizes, it often affects the bones, lungs or liver.
Prostate cancer also often metastasizes to the bones and lymph nodes, and at times to the liver or lungs. Metastases from bowel cancer often spread to the peritoneum or lymphatic system.
Is slowing metastasized cancer the only option? Or can it be stopped?
Once metastases have appeared, the progression of the disease can generally only be slowed.
Researchers are working hard to clarify the mechanisms behind metastasis. Many scientists believe that in order to develop new treatments, we first have to fully understand the docking mechanism used by cancer cells to gain a foothold elsewhere in the body, as well as how the tumor ensures a steady supply of blood.
Many of the interactions that take place between cancer cells and cells in the surrounding healthy tissue remain unexplained. "For example, the body produces a range of hormones that eventually cause reprogramming in the surrounding blood vessels,” explains Weg-Remers. "When researchers are able to trace and understand these mechanisms, that will likely open the door to new therapeutic approaches.”
12 ways to prevent cancer
Cancer doesn't have to be an inevitable destiny. Scientists know exactly what triggers the disease. And everyone can do something against the biggest threats.
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Destiny is in your hands
Being diagnosed with cancer is a shock that hits you hard. And yet almost half of all cancer cases could be prevented. Smoking alone triggers about every fifth tumor. The toxic cigarette smoke does not only cause lung cancer but many other kinds of tumors as well. Smoking is the most frequent self-imposed cause for cancer, but not the only one.
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Being overweight increases cancer risk
In second place of cancer-causing agents: obesity. Why it causes cancer? Enhanced insulin levels increase the risk of almost all sorts of cancer, especially when it comes to kidney, gall bladder, and oesophagus cancer. Overweight women produce increasing amounts of female sex hormones in their fat tissue and hence have a higher risk for uterine or breast cancer.
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Don't be a couch potato!
People who don't move enough are especially likely to get cancer. Long-term studies show that exercising prevents tumors. After all, working out lowers the insulin levels while preventing you from gaining weight. And it doesn’t have to be high-performance sport. Even just going for a walk or a bike ride makes a big difference.
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Don't drink too much!
Alcohol promotes tumors in the oral cavity, the throat and the oesophagus. The combination of smoking and drinking is especially dangerous and increases the risk of cancer up to a hundredfold. While dinking one glass of wine a day is healthy and supports the cardiovascular system, you shouldn’t drink more than that.
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Don't eat too much red meat!
Red meat can cause intestinal cancer. The exact cause has not yet been determined, but long-term studies show a significant correlation between the consumption of red meat and intestinal cancer. Beef is especially dangerous, but even pork can cause cancer to a minor degree. Meat consumption increases the risk of cancer one and a half times. Fish, however, prevents cancer.
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No more BBQ?
When barbecuing meat, carcinogenic substances are released, such as polycyclical aromatic hydrocarbons. It has been proven in animal experiments that these chemical compounds can cause tumors. However, long-term studies with humans have not yet unambiguously proven the same. It’s possible that consuming the meat causes cancer, not the way it is prepared.
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Avoid fast food
A good diet consisting of vegetables, fruits and dietary fibers can prevent cancer. However, when conducting long-term studies researchers found that a healthy diet has less impact on cancer prevention than previously assumed. It only decreases the risk of getting cancer by a maximum of 10 percent.
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Too much sun is harmful
The sun’s UV radiation can penetrate genomes and change them. While sunscreen protects the skin from sunburn, the skin absorbs too much radiation as soon as it starts getting tanned.
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Cancer triggered by modern medicine
X-rays harm genomes. With an ordinary radiogram the exposure is only minor. But it’s a different story for computed tomography, which you should only undergo when necessary. Magnetic resonance imaging is harmless. But did you know that you’re even exposed to cancer-causing radiation when you’re on an airplane?
Image: picture alliance/Klaus Rose
Cancer triggered by infection
Human papillomaviruses can cause cervical cancer. Hepatitis B and C can cause hepatocytes to degenerate. The bacterium helicobacter pylori (pictured above) settles in your stomach and can cause stomach cancer. But not all hope is lost. You can get vaccinated against many of these pathogens and antibiotics help fight helicobacter pylori.
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Better than its reputation
The oral contraceptive pill slightly increases the risk of getting breast cancer, but at the same time it strongly decreases the risk of getting ovarian cancer. All in all the pill is more protective than harmful, at least when it comes to cancer.
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A true stroke of fate
But even if you do everything right, you’re never completely immune from getting cancer. Half of all cancer cases are caused by the wrong genes or simply age. Brain cancer is particularly likely to be inherited.
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Bitter truth about sugar
Sugar is tasty, but not exactly good for you. Consumption of the sugary stuff is rising, and that’s having an impact on health. The WHO has warned of a “global epidemic.” Here are a few facts you really should know.
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Sugar makes you fat!
Sugar is converted to fat in the body about two to five times more quickly than starches. In other words, when we consume sugar, we’re feeding our fat cells. The fructose in sugar is also metabolized by the liver, which can contribute to fatty liver disease. That can promote insulin resistance and lead to Type 2 diabetes – with a lifelong impact on your health.
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Sugar affects your mood!
In small amounts, sugar promotes the release of serotonin, a hormone that boosts mood. But too much sugar can promote depression and anxiety. Sudden shifts in blood sugar levels can also lead to irritability, anxiety and mood swings.
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Sugar contributes to aging!
We already know that sugar has a variety of health effects, but it also affects the skin. That’s in part due to glycation, the process whereby sugar molecules bind to collagen fibers. As a result, the collagen fibers lose their natural elasticity. Excess sugar also damages microcirculation, which slows cell turnover. That can promote the development of wrinkles, make you look older than your age.
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Sugar is harmful to your gut!
The microflora of your gut promote digestion and protect your digestive system from harmful bacteria. Consuming too much sugar gets your gut microflora out of whack. Fungi and parasites love sugar. An excess of the Candida albicans yeast can lead to a host of annoying health symptoms. And sugar also contributes to constipation, diarrhea and gas.
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Sugar can be addictive!
In overweight people, the brain responds to sugar by releasing dopamine, in much the same way that it responds to alcohol or other addictive substances. Test it yourself: avoid all sugary foods and beverages for ten days. If you start to get headachy and irritable after a day or two, and start craving sugar, then you could be suffering from sugar withdrawal.
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Sugar makes you aggressive!
People who consume excess sugar are more likely to engage in aggressive behavior. Children with ADHD are also affected by sugar. For these children, too much sugar affects concentration and promotes hyperactivity. That’s why it’s a good idea for children to avoid eating sugar during school hours.
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Sugar weakens the immune system!
Excessive sugar consumption makes it harder for the immune system to ward off disease. After consuming sugar, the immune system’s ability to kill germs is reduced by up to 40 percent. Sugar also saps the body’s store of vitamin C, which white blood cells need to fight off viruses and bacteria. Sugar also promotes the inflammatory response, and even minor inflammation can trigger numerous diseases.
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Sugar promotes Alzheimer’s disease!
Studies have shown that excess sugar consumption increases the risk of developing Alzheimer’s disease. A 2013 study showed that insulin resistance and high blood sugar values – both of which are common in diabetes – are associated with a higher risk of neurodegenerative diseases such as Alzheimer’s.
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Sugar increases cancer risk!
Cancer cells need sugar to proliferate. An international research team headed by Lewis Cantley of Harvard Medical School is researching how sugar might contribute to the growth of malignant cells. He believes that refined sugar may be what causes cancer cells to develop into tumors. He’s still testing that hypothesis but recommends that even slender people consume as little sugar as possible.
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Sugar makes you stupid!
Excess sugar consumption may have a negative impact on memory. According to a study carried out by Berlin’s Charité University Hospital, people with high blood sugar levels have a smaller hippocampus – the part of the brain that’s key to long term memory. In the study, people with high blood sugar also performed more poorly on tests of memory than those with low blood sugar levels.
