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Medical Forum / General / General / June 2005Questions: Angiogenesis in Cancer
Hello, I have following thoughts about Angiogenesis & request you to awnser these after serious thinking:- When cancer is in tumor stage it is considered that cancer cell can encourage Angiogenesis for their nutrition, multiplication & spread. But, I think that there can be two conditions related to it. 1.On naturally improved/biologically medicated immunity:- when a person gets cancer, our immune system should be trying to kill/correct the cabcer cells. But when our immune system couldn't handle these due to required immune strength, cancer cells then may opt to arrest/encapsule these in tumor etc.in cansiderations of (a)to starve them by inhibiting blood supply or their respiration or nutrients (b)to restrict & resist there growth & spread (c)to hold them in encapsuled/tumor state & pursue to improve the immunity or wait for right time/immunity level, when it can handle/kill thise cancer cells. 2.On weakening of immunity (natural or otherwise):- It may encourage cancer cells to multiply & spread as progress of disease. I can't say whether it can be Angiogenesis oriented or not? Now my questions are: 1.Are cancer cells or other disease causing agents in tumor/latencies capable of encouraging Angiogenesis, in view of that it os our body's immune defence mechanism? 2. Can it be thought/possible that Angiogenesis is an immune defence mechanism "On naturally improved/biologically medicated immunity" as I described above, either to transport immune agents in tumor to kill them OR to encourage them to resurface/take out from tumor for exposure to immune system for killing them? 3. Can it be also thought that Angiogenesis may not be possible "On weakening of immunity (natural or otherwise)" as I described above? In short, can it be dynamically thought that, somewhat spread or resurfacing of cancer cells & Angiogenesis can occur on improved immunity to kill those as a "direction towords cure" instead of "direction towords progress of disease"? This aspects may also be thought for other latencies. I think it is nowhere clearly mentioned, what happens when a person with latent infections or cancer strengthened his immune system, naturally, at some later date? Can it handle/cure latencies & cancer? Best wishes. From what I've learned antiogenesis is not related to any other system except that it serves to provide nourishment to the cancer site. At the same time, this main "mass" produces anti-angiogenesis compounds which prevent other sites from "robbing" the primary site of blood flow/nutrients. It has been observed that in many case removal of the primary mass, and it's anit-angiogenesis function, allows other sites to become more active. This reminded me of things my parents would say decades ago about people they knew who had cancer, things like "Oh, as soon as they removed "the cancer" it spread all over." etc. They believed that the surgery cause the cancer to spread because it had been disturbed. Interesting. > Hello, > [quoted text clipped - 45 lines] > > Best wishes. Yes, we may need to understand about cancer & other latent conditions more deeply--what is to body's immune defence mechanism on strengthning of immune system--medicated or natural? Whether strong immune system can handle them within tumor or they need to be exposed & come out of tumor to kill them be immune system? Can immune system kill cancer cells within tumor, when it is suitably strong? Taruma, injury, stresses, infections etc. can weaken immune system, so we should understand surgery to this effec >Yes, we may need to understand about cancer & other latent conditions >more deeply--what is to body's immune defence mechanism on strengthning [quoted text clipped - 5 lines] >Taruma, injury, stresses, infections etc. can weaken immune system, so >we should understand surgery to this effec If only things were so simple -- if only immune systems could be simply characterised as "strong" or "weak", like muscles! The really hard part is that a cancer isn't like an infection. It's made up of your own cells, which your body will and should identify as "self" not "invader". Is an immune system "strong" or "weak" when it gets confused about self and other and attacks normal tissues, causing disease like type 1 diabetes, multiple sclerosis, rheumatoid arthritis, lupus and many others? Immunotherapies for cancers are continually being developed. The idea is to get the patient's immune system to regard the cancer as "alien" and attack it. These methods are always promising, but never good enough to get into standard use. But the effort is certainly worthwhile, even though it's known that cancers will mutate fast enough to evade even an immune system that has been sensitized to them. Further research may result in more reliable immunotherapies. The immune system is believed to be involved in suppressing virally induced cancers at an early stage. We have an experiment of nature in the form of the several viral-caused cancers that are so common in HIV+ individuals. People who take immune-suppression drugs in connection with organ transplants also develop cancers at an unusually high rate. Cancer is mainly a disease of older people, and the immune system becomes less effective with age, although this particular correlation is not the best evidence for causation. AFAIK, the best theory about spontaneous remissions is that the patient's immune system suddenly decides that the cancer is alien, and attacks and destroys it as an invader. Immunotherapy is an effort to induce this effect artificially, and it's a very active area of research. It's not simple, because finding a marker the immune system can identify, that isn't found on any normal cell, is not trivial. As far as angiogenesis, the immune system acts through white blood cells and antibodies carried in the blood. If a tissue has no blood supply, the immune system can't act in it. But a tissue with no blood supply isn't going to grow, or in most cases, survive. A tumor that can express angiogenesis promoting factors will survive and grow. Most cancers aren't very good at providing themselves with an effective blood supply throughout and die at the core of the tumor, resulting in the appalling smell many cancer patients develop as the dead tissue breaks down while the tumor continues to grow nearer its surface, and in metastatic tumors which have a higher ratio of surface to volume. "If only things were so simple -- if only immune systems could be simply characterised as "strong" or "weak", like muscles!" Many thanks for quite imformative reply. Anyhow, I feel some problem in our understanding of immune system's role in cancer & other latencies. "The really hard part is that a cancer isn't like an infection. It's made up of your own cells, which your body will and should identify as "self" not "invader". Is an immune system "strong" or "weak" when it gets confused about self and other and attacks normal tissues, causing disease like type 1 diabetes, multiple sclerosis, rheumatoid arthritis, lupus and many others?" Is it not in some very earlier stage of getting cancer that it is difficult to differenciate the cancer cells with our cells? I think, getting cancer cells encapsuled in tumor, indicate that immune system has recognized them & started working on that alike other latencies. Otherwise why tumor formation will take place? "Immunotherapies for cancers are continually being developed. The idea is to get the patient's immune system to regard the cancer as "alien" and attack it. These methods are always promising, but never good enough to get into standard use. But the effort is certainly worthwhile, even though it's known that cancers will mutate fast enough to evade even an immune system that has been sensitized to them. Further research may result in more reliable immunotherapies." I think numbers of angiogenesis stimulators & inhibitor may be mediated by immune system--when it is strong, more can be the inhibitors and when weak, more can be the stimulators in normal circumstances. I am not sure if stimulators can be encouraged on improved immunity to promote angiogenesis as I indicated previously. It looks to me that we are bit unclear about, what happens on getting improved/strong immune system as we may mistake or fear not to take chances as there can be somewhat similar symptoms of spread/coming out of cancer cells from tumor if encouraged by improved immunity or is cancer is progressed. Truma, stress, infections etc may again weaken immune system & these may interfere in natural cure on improved immunity. "The immune system is believed to be involved in suppressing virally induced cancers at an early stage. We have an experiment of nature in the form of the several viral-caused cancers that are so common in HIV+ individuals. People who take immune-suppression drugs in connection with organ transplants also develop cancers at an unusually high rate. Cancer is mainly a disease of older people, and the immune system becomes less effective with age, although this particular correlation is not the best evidence for causation. " All these tell me that, it is weak or strong immune system that works or not work on cancer. "AFAIK, the best theory about spontaneous remissions is that the patient's immune system suddenly decides that the cancer is alien, and attacks and destroys it as an invader. Immunotherapy is an effort to induce this effect artificially, and it's a very active area of research. It's not simple, because finding a marker the immune system can identify, that isn't found on any normal cell, is not trivial." As I indicated, I think immune system understand the cancer cells different from normal cells which causes tumor formations. But the problem can be that who will take chance & how to check, whether immune system is suitably strong or not to handle cancer cells? "As far as angiogenesis, the immune system acts through white blood cells and antibodies carried in the blood. If a tissue has no blood supply, the immune system can't act in it. But a tissue with no blood supply isn't going to grow, or in most cases, survive. A tumor that can express angiogenesis promoting factors will survive and grow. Most cancers aren't very good at providing themselves with an effective blood supply throughout and die at the core of the tumor, resulting in the appalling smell many cancer patients develop as the dead tissue breaks down while the tumor continues to grow nearer its surface, and in metastatic tumors which have a higher ratio of surface to volume." It is very relevant to my doubts. How immunotherapy or naturally strengthened immune system can work when cancer cells are still in tumor? Tumor formations can be a immune system's work meant for--to starve cancer cells OR to restrict & resist their growth OR to wait & prepare for right time of suitably strengthened immune system. It may be mediated via angiogenesis inhibitions. >Many thanks for quite imformative reply. Anyhow, I feel some problem in >our understanding of immune system's role in cancer & other latencies. There are many unsolved problems. The immune system in health and disease is incredibly complicated. >Is it not in some very earlier stage of getting cancer that it is >difficult to differenciate the cancer cells with our cells? I think, >getting cancer cells encapsuled in tumor, indicate that immune system >has recognized them & started working on that alike other latencies. >Otherwise why tumor formation will take place? No, a tumor is a mass of abnormal cells, not a structure formed by the body's attempts to encapsulate an infection, as often happens in latent tuberculosis and other infections. Even very advanced and extremely abnormal cancer cells are usually accepted as "self" and not attacked by the immune system. Note that the immune system itself performs powerful selection here -- if a cancer cell mutates to a form that is regarded as alien by the immune system, it will be attacked and destroyed, leaving the "self" type cancer cells to proliferate unchecked. Unfortunately, the body doesn't have much in the way of natural defenses against cancer, because cancers usually occur in organisms which have already done most or all of the reproduction they are capable of, so there can't be much selection for such mechanisms. There are cell-level mechanisms that prevent some of the early events that can lead to carcinogenesis, but one of the important steps in carcinogenesis is mutations that make these mechanisms ineffective. Once the cell-level mechanisms are bypassed, there usually isn't much to restrain proliferation, and any further mutation (common in the absence of the quality-control) that gives that cell the ability to behave more aggressively as an anarchic cancer cell line will flourish. You have a number of interesting and self-consistent ideas, but unfortunately some of your premises are incorrect, so your conclusions are not valid. Thanks again. If this is true, how biological/ immunotherapy for cancer can work? >Thanks again. If this is true, how biological/ immunotherapy for cancer >can work? Sometimes a surface antigen can be identified on the cancer cells that is enough unlike normal forms that it may be possible to sensitize the immune system to it. There are a variety of techniques of doing so, and they sometimes involve injecting the proposed antigen together with other antigens that are known to stimulate antibody formation. This is similar to some older methods of making vaccines for certain diseases. Unfortunately, while clinical trials are often promising, AFAIK, no generally effective immunotherapies have been developed yet, but I'm not following the field, so there may be successes I don't know about. It's been a promising approach for a long time. Note that while an ideal cancer treatment would truly eliminate all cancer cells, one that slows progression or causes a remission of months or years is still very valuable. Immunotherapy would be less damaging to normal tissues than most current treatments, and might be used to shrink tumors, followed by chemotherapy or other techniques to attempt to kill any surviving cancer cells. "Unfortunately, the body doesn't have much in the way of natural defenses against cancer, because cancers usually occur in organisms which have already done most or all of the reproduction they are capable of, so there can't be much selection for such mechanisms." Sorry, I was willing to know that when our defence system do not work against cancer in view of your above quote, how immunotherapies can be thought to work? "If only things were so simple -- if only immune systems could be simply characterised as "strong" or "weak", like muscles!" Many thanks for quite imformative reply. Anyhow, I feel some problem in our understanding of immune system's role in cancer & other latencies. "The really hard part is that a cancer isn't like an infection. It's made up of your own cells, which your body will and should identify as "self" not "invader". Is an immune system "strong" or "weak" when it gets confused about self and other and attacks normal tissues, causing disease like type 1 diabetes, multiple sclerosis, rheumatoid arthritis, lupus and many others?" Is it not in some very earlier stage of getting cancer that it is difficult to differenciate the cancer cells with our cells? I think, getting cancer cells encapsuled in tumor, indicate that immune system has recognized them & started working on that alike other latencies. Otherwise why tumor formation will take place? "Immunotherapies for cancers are continually being developed. The idea is to get the patient's immune system to regard the cancer as "alien" and attack it. These methods are always promising, but never good enough to get into standard use. But the effort is certainly worthwhile, even though it's known that cancers will mutate fast enough to evade even an immune system that has been sensitized to them. Further research may result in more reliable immunotherapies." I think numbers of angiogenesis stimulators & inhibitor may be mediated by immune system--when it is strong, more can be the inhibitors and when weak, more can be the stimulators in normal circumstances. I am not sure if stimulators can be encouraged on improved immunity to promote angiogenesis as I indicated previously. It looks to me that we are bit unclear about, what happens on getting improved/strong immune system as we may mistake or fear not to take chances as there can be somewhat similar symptoms of spread/coming out of cancer cells from tumor if encouraged by improved immunity or is cancer is progressed. Truma, stress, infections etc may again weaken immune system & these may interfere in natural cure on improved immunity. "The immune system is believed to be involved in suppressing virally induced cancers at an early stage. We have an experiment of nature in the form of the several viral-caused cancers that are so common in HIV+ individuals. People who take immune-suppression drugs in connection with organ transplants also develop cancers at an unusually high rate. Cancer is mainly a disease of older people, and the immune system becomes less effective with age, although this particular correlation is not the best evidence for causation. " All these tell me that, it is weak or strong immune system that works or not work on cancer. "AFAIK, the best theory about spontaneous remissions is that the patient's immune system suddenly decides that the cancer is alien, and attacks and destroys it as an invader. Immunotherapy is an effort to induce this effect artificially, and it's a very active area of research. It's not simple, because finding a marker the immune system can identify, that isn't found on any normal cell, is not trivial." As I indicated, I think immune system understand the cancer cells different from normal cells which causes tumor formations. But the problem can be that who will take chance & how to check, whether immune system is suitably strong or not to handle cancer cells? "As far as angiogenesis, the immune system acts through white blood cells and antibodies carried in the blood. If a tissue has no blood supply, the immune system can't act in it. But a tissue with no blood supply isn't going to grow, or in most cases, survive. A tumor that can express angiogenesis promoting factors will survive and grow. Most cancers aren't very good at providing themselves with an effective blood supply throughout and die at the core of the tumor, resulting in the appalling smell many cancer patients develop as the dead tissue breaks down while the tumor continues to grow nearer its surface, and in metastatic tumors which have a higher ratio of surface to volume." It is very relevant to my doubts. How immunotherapy or naturally strengthened immune system can work when cancer cells are still in tumor? Tumor formations can be a immune system's work meant for--to starve cancer cells OR to restrict & resist their growth OR to wait & prepare for right time of suitably strengthened immune system. It may be mediated via angiogenesis inhibitions. Yes, we may need to understand about cancer & other latent conditions more deeply--what is to body's immune defence mechanism on strengthning of immune system--medicated or natural? Whether strong immune system can handle them within tumor or they need to be exposed & come out of tumor to kill them be immune system? Can immune system kill cancer cells within tumor, when it is suitably strong? Taruma, injury, stresses, infections etc. can weaken immune system, so we should understand surgery to this effect AND wound etc. may encourage angiogenesis.
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