Biology of Cancer and AIDS Microbio 160 Why Screen Lecture 13 Cancer Screening Diagnosis and Treatment Screening tests can help find cancer at an early stage before symptoms appear When abnormal tissue or cancer is found early it may be easier to treat or cure By the time symptoms appear the cancer may have grown and spread This can make the cancer harder to treat or cure It is important to remember that when your doctor suggests a screening test it does not always mean he or she thinks you have cancer Screening tests are done when you have no cancer symptoms Fatigue weight loss night sweats blood in urine chronic cough loss of appetite recurrent fever sudden depression new persistent pain enlarged lymph nodes recurrent nausea blood in stool recent change in bowel habits changes in size or color of mole Warning Signs Types of Tests Physical exam and history An exam of the body to check general signs of health including checking for signs of disease such as lumps or anything else that seems unusual A history of the patient s health habits and past illnesses and treatments will also be taken Laboratory tests Medical procedures that test samples of tissue blood urine or other substances in the body Imaging procedures Procedures that make pictures of areas inside the body Genetic Tests Tests that look for certain gene mutations that are linked to some type of cancer Imaging Techniques Magnetic Resonance Imaging MRI o Uses magnets to energize electrons o Release of energy image Computed Tomography CT or CAT scan Ultra sound o Uses sound waves Positron Emission Tomography o Uses multiple high resolution x rays to generate a composite image A nuclear medical imaging technique that produces a three dimensional image or picture of functional processes in the body Detects pairs of gamma rays emitted indirectly by a positron emitting radionuclide tracer which is introduced into the body on a biologically active molecule Three dimensional images of tracer concentration within the body are then constructed by computer analysis If the biologically active molecule chosen for PET is FDG a glucose analogue the concentrations of tracer imaged give tissue metabolic activity in terms of regional glucose uptake Use of this tracer to explore the possibility of cancer metastasis is the most common type of PET scan in standard medical care 90 of current scans Risky Not all screening tests are helpful and most have risks Some screening procedures can cause bleeding or other problems For example colon cancer screening with sigmoidoscopy or colonoscopy can cause tears in the lining of the colon It is important to know the risks of the test and whether it has been proven to decrease the chance of dying from cancer False Results Screening test results may appear to be abnormal even though there is no cancer A false positive test result one that shows there is cancer when there really isn t can cause anxiety and is usually followed by more tests and procedures which also have risks Screening test results may appear to be normal even though there is cancer A person who receives a false negative test result one that shows there is no cancer when there really is may delay seeking medical care even if there are symptoms Sensitivity and Specificity Sensitivity addresses what of people with a given cancer will have that cancer detected with a particular test If a test is not sensitive there will be a lot of false negative results Specificity of a test is concerned with what of people who do not have cancer are correctly identified as being cancer free If a screening test is not very specific it will yield many false positives The Ideal Screen The perfect screen o Would never have any false positive results Determine a person has cancer when he or she actually does not o Would never have any false negative results Miss the cancer in a person that actually has cancer o The perfect screen does not exist Is early detection always beneficial Some cancers never cause symptoms or become life threatening but if found by a screening test the cancer may be treated There is no way to know if treating the cancer would help the person live longer than if no treatment were given Also treatments for cancer have side effects For some cancers finding and treating the cancer early does not improve the chance of a cure or help the person live longer Common Screens Skin Cancer physical exam routine check up Lung cancer chest x ray not recommended routine Rectal stool exam yearly after 50 Prostate rectal exam yearly after 50 Testicular self exam monthly after 14 Cervical pelvic exam every 1 3 years Breast cancer physical exam monthly after 18 Treatments Surgical Surgical removal of tumor or part of tumor A K A Resection total or partial Treatments Chemotherapy Chemotherapy o Treatment of cancer with one or more cytotoxic antineoplastic drugs as part of standardized regimen o 2 types Traditional which kills rapidly dividing cells Targeted antibody therapy More about Chemotherapy There are over 100 different drugs available to treat cancer Each has different properties and functions for destroying cancer cells Alkylating agents destroy the DNA of a cell to prevent it from reproducing Anti tumor antibiotics destroy the enzyme a cell needs to reproduce its DNA Mitotic inhibitors prevent cells from obtaining the protein needed for survival Routes of administration pill intramuscular injection IM intravenous administration IV Treatments Radiation Radiation therapy o Medical use of ionizing radiation o Damages DNA of cells o Induces apoptosis not specific o Given in fractioned doses o Effect is cumulative Radiation Treatment Planning In radiotherapy radiation treatment planning is the process in which a team consisting of radiation oncologists radiation therapist medical physicists and medical dosimetrists plan the appropriate external beam radiotherapy or internal brachytherapy treatment technique for a patient with cancer Intent is to maximize tumor damage and minimize impacts on healthy tissue Radiation affects cancer and normal Cells normal cells recover Treatment Intent Combined modality drugs other cancer treatments radiation surgery Most cancers are now treated in this way Advantage is minimizing chances of resistance developing to any one agent Neoadjuvant preoperative treatment designed to shrink the primary tumor thereby rendering local therapy surgery or radiotherapy less destructive or more effective Adjuvant postoperative
View Full Document
Unlocking...