EEMB 50 Non Infectious Diseases
EEMB 50 Non Infectious Diseases
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Date Created: 04/18/14
EEMB 50 NON Infectious Diseases April 13 Lecture 7 Cancer Screening Caner is a series of steps not a single event Tumors need to learn how to grow through the formation of new blood sources vessels avoid cell death and mutate both tumor suppressor genes Leonard Hay ick demonstrated that a population of normal fetal cells in a cell culture can only divide between 40 to 60 times before they die This is because of the Hay ick method which is the explanation as to why cells stop dividing after a certain point 1 Telomeres shorten at every division and lead to programmed senescence and acting as a check on cancer 2 Telomeres are caps on chromosomes that help them retain their form shape without unwinding 3 Each time a cell replicates the telomere gets shorter reaching the point where the cell eventually dies 4 Some cancers are able to avoid this by producing telomerase which prevents telomeres shortening it rebuilds the telomere so there is no limit to how many times a cell can replicate 5 All cells have the ability to do this but they do not 6 This evolved many think as a check on cancer and as an explanation to one of the things that cause aging in humans HeLa Cells came from a woman named Henrietta Lacks who died of cervical cancer in 195 1 1 Cells taken from her tumor are among the oldest and most common cells used 2 They are believed to be immortal because they are the longest living line of human cells 3 Aggressive cell line growing line Once a caner is malignant and starts growing out of control has its own blood supply and begins to spread it becomes very dangerous They have exponential growth as they begin to multiply For a cancer to be detected it takes about 10quot 9 cells but by that time many that cancer will already spread or it may be too late to remove Cancer cells start to slow down cell growth rate as it starts to become resource limited and is spreading to much of the body as it is competing with the host Metastatic cancer vs nonmetastatic cancer 1 M cancer is harder to remove and more complicated treatments used to treat it 2 NM cancer is less dangerous to remove and after removal it is more likely that the cancer did not have time to spread elsewhere throughout the body BUT STILL CHANCE OF DEATH FROM A NM CANCER How cancer kills Infection before antibiotics were available 1 Cancer cells have a chaotic growth rate and are able to grow faster than blood cells some may die and become infected 2 There are blood vessels that can also be growing faster than the tumors themselves and lead to bleeding infection Loss of function 1 Some cancers can grow so large in organs like the kidney or liver that there is not enough organ left to do its function organ failure death 2 Ex with brain cancer loss of a small fraction can lead to death because in this example parts that are in control of breathing die Disrupt homeostasis 1 Homeostasis is the ability of an organism to maintain internal equilibrium by adjusting its physical processes 2 Example Bone cancer releases excess Calcium into the blood that it cannot be regulated anymore 3 People can literally waste away as the cancer changes the bodies equilibrium Competition for resources 1 When a cancer is competing with your body for resources that it becomes so large you have to fight against it 2 Rarely seen today because of medical advances and detection of cancers Metastatic Cancer 1 Because it travels to other parts of your body there is a high risk it can spread to vital organs making surgeries more complicated and dangerous 2 Detecting cancer early is incredibly important before it metastasizes because then it can be surgically removed and possibly cured 3 Cancer control reduce risks discourage people from smoking and screening to catch cancers early and have a better and higher chance of curing it Cancer Screening some are very useful some not useful and some even potentially dangerous 1 CT Scan Lung Cancer and all sorts used to scan for many cancers smokers over the age of 50 are rec to take the scan CT Scans are expensive and there is a lot of advertising to promote it Do Not do it unless you are sure you have high risks because many times the outcomes of the tests are more dangerous than the actual cancer could have caused 2 PSA Test Prostate Cancerit is a chemical test that tests for high levels of the chemical it used to be recommended annually for men over 50 but that has declined over the yrs 3 Pap Smear Cervical Cancer cytological test for women over 21 and done every 3 5 yrs the test examines the shape and the form of specific cells to see for irregularities 0 CT Scans and lung cancer 0 Lung cancer is one of the most common and with a low survival rate after detection 0 Spiral CT Scan X Ray computed tomography 1 Get slices of your body as the machine moved down your body it is on a circular track that spins done in 30 seconds and is also able to detect how much x rays penetrate into your body 2 It detects the cancers the size of an eraser smaller than anything we could have been able to visually see before 3 Typically the tumors of this size in our lungs would be asymptomatic and would have not metastasized yet and in theory would be considered curable 4 Problem with these scans are that they detect cancers that would potentially be dangerous or deadly to you this would lead to identification as a cancer patient and be given treatment for cancers that would not hurt you while the side effects of the medicine would harm you 5 Screening is only worthwhile if it can detect and cure cancers that have ultimately killed people 6 Detecting cancers that haven t shown symptoms is in a way pointless and dangerous as the radiation given from these scans can actually cause you cancers that will be dangerous and metastasize 7 The risks of treatment also come with risks 0 Ex In Lung Cancer removal of tumors in the lungs surgically can be messy and risky and even come with a mortality rate of 25 0 Overdiagnosis false positive a false positive result of a tumor that will never cause death but is treated a cancer 0 A Good Screening program cures cancers that would otherwise kill people 0 Bad Screening program cures cancers that would not kill people 0 Overscreening diagnoses many people with a positive result and sent to secondary test 0 Lead time bias Leam about cancer sooner so think that ur survival rate increases but in reality it is the same than that of a person who would have not known about it and still lived same amount of time as the treated person ex in Lung cancer 0 Once Cancer turns too deadly it is too late to cure and removal of lung may be deadly 0 We start the clock sooner and we do not want to do this 0 Solution 1 Be able to distinguish tumors that will never become dangerous and ones that Will but this is difficult as Well because it all depends on mutation and We do not know which will become lethal and which will not