They can remain inactive for a long time, up to the time when a specific stimulus wakes Dornröschen these cells and micrometastases can gain strength to adult tumors. Today puzzled physicians what these stimuli and of course, how they can be best addressed.
The idea that surgery could worsen the cancer is not new. Previously it was believed that an operative exposure of a tumor that could be active by contact with the air. This belief, however, more common among the patients than among physicians. There was also no compelling evidence that something could be consistent with this theory.
Another theory, which sounds a bit more plausible and more likely, says that by the surgical removal of a tumor is not first, all malignant cells can be removed at 100 percent. These frequencies can later grow to a new place of origin and act. Second, cancel the operation by the tumor cells and other tissues "washed", where they implant themselves and take care of the dreaded metastases.
What did not make the biology of tumor growth and metastasis, then the surgical intervention would have passed successfully. But here, too, we know nothing for certain. At least there are no reliable data on the issue of whether a tumor removal is accompanied by operation with a life-prolonging effect.
So might be something on the second turn theory: if the tumor is gone, but fails the life-prolonging effects, could then operation-related metastases and remaining tumor cells provide for the negative effect.
A third theory suggests further, new mechanisms that make the negative effects of surgery on tumor occurrence likely. In this context, two names are: Dr. Michael Retsky of Harvard Medical School in Boston and Dr. Nils Hansen ALGENSTAEDT of the University Hospital in Hamburg.
In this theory, the scientists suspect that the operation itself may be the trigger for the rapid growth of smaller tumors. So far, the cancer experts are still skeptical about these allegations against. But their followers see more and more evidence for this theory. Dr. Retsky believes that at least in some cases, surgery does more harm than it benefits the patient. This is especially true for breast cancer patients. Dr. Retsky argued that more than half of these patients relapse accelerated by an operation or may have been brought about. But he does not rule out that this phenomenon can also be observed in other types of cancer.
The mechanism that hides behind this is not yet fully known. But we know already for some decades that surgery stimulates the production of proteins and other substances by the organism to ensure healing.
So if someone is operating, then a cascade of genetic signals is set in motion, which favors the growth conditions for a 'dormant' tumor. This hypothesis focuses on a different area of cancer research, which is primarily concerned with angiogenesis (the formation of new blood vessels) in cancer cells. It has been shown that a tumor, as any other healthy cell also requires a supply system. The difference to the healthy cell, however, is that the tumor cell is in a position to accomplish much better and faster, the formation of blood vessels. This realization then the birth of chemotherapy, which was trying to prevent these angiogenesis (see Avastin).
Unfortunately, however, these drugs also prevent the normal wound healing and have other serious side effects. Due to the injury caused by surgery, it is in the body to an increased formation of blood vessels at the site of injury. The greater the injury added, the more "violent" this repair mechanism is used. At the same time, this mechanism also provides the necessary substances that stimulate dormant tumor cells to grow.
But not only this mechanism is unleashed by surgery. Today, we know that is a primary tumor in a position to oppress others, smaller tumors. This seems to be having a big reason why not metastases occur immediately and in large numbers. Surgical removal of such a large primary tumor, however, would remove this brake on the small. If then at the same time through an extensive tissue injury, the mechanisms necessary for tissue repair and blood vessel formation are turned on, are for the small tumor cells "paradisiacal conditions" before.
Whether this is so when people look like is still uncertain, because there are few studies on this topic. But there are relevant studies that have shown this issue in mice.
Cancer cells produce, as mentioned above, agents that induce angiogenesis and accelerate. The "sleep mode" of the metastatic cells is characterized by a balance between cell proliferation and apoptosis (natural cell death, cell suicide). An increase in the rate of apoptosis would thus destroy some time after these metastases completely.
Surgical removal of the primary tumor, but this balance is changed in favor of cell proliferation. As a reason, the authors of the stimulation of angiogenesis, which effects the growth of micrometastases in clinically relevant metastases. Therefore, the authors an effective drug at reducing these angiogenesis after surgery.
But even here one tries to drive out the devil with Beelzebub. For such a treatment would not only curb the growth of metastatic foci, but also curtail the self-healing capacity of the body.
Accordingly high then the side effects of "chemotherapy" are. Rather be here in an unavoidable surgery (tumors that vital organs affected or drive, for example) to strive to keep the extent of the injuries to a minimum. For it is only logical that when a major injury as "powerful" repair mechanisms must come into play, which in turn increases the stimulus for the dormant metastatic cells. Thus, not only surgery would have been qualified for the wake of cancer cells. Even more serious injuries in accidents e.g. could this mechanism in motion.
No comments:
Post a Comment