Cancer in the Family. Part 1 Running Pains

Transcription

1 Part 1 Running Pains Stacey is a healthy, active 12- year- old. She is beginning 7 th grade and is excited about starting cross- country season this fall. A few weeks ago, Stacey noticed a pain in her left knee. She has been training all summer and didn t want to spend the season injured. So, she decided to talk to her step- dad, a marathon runner, about the pain. Hi Paul, Stacey began. I ve been having some pain in my left knee. I don t want to risk it developing into a major injury before cross- country season begins. Do you have any advice on what I should do? It s probably just a little swollen from overuse and needs some rest. You have been running an awful lot lately. Let s try icing it over the next few weeks, Paul responded thoughtfully. If it isn t feeling better in a few weeks, we will take you to the doctor to make sure it isn t something serious. Over the next month, however, the pain in Stacey s knee only got worse. Paul decided it was time to take her to her regular pediatrician, Dr. Smith. Dr. Smith initial suspects that it is probably growing pains and prescribes Stacey rest and ibuprofen to reduce the swelling. When the pain persists, he decides to x- ray the knee. During an x- ray, x- ray beams are passed through the body, which are absorbed in different amounts depending on the density of the material they pass through. Dense materials appear white in an x- ray, while less dense materials appear black. SJCRH; Cancer in the Family by Katherine Ayers 1

2 Questions: 1. Why does Stacey s step- dad decide to take her to the pediatrician? Students should be able to pull data from the text related to Stacey s symptoms: she has pain and swelling in her left knee that seems to be getting worse. 2. Why does Dr. Smith decide to order the x- ray? Students should be able to pull data from the text related to Stacey s persisting pain even after rest and ibuprofen. 3. Compare and contrast Stacey s x- ray with a normal x- ray. What differences do you notice? Normal X- ray Stacey s X- ray Give students time to analyze the images either as groups or individually. While it is unlikely that students will understand the significance of the differences, students should be able to note that Stacey s bone near her near appears fuzzy or cloudy. The edges of the bone are not as clearly defined in the x- ray of Stacey s knee as they are in the x- ray of the normal knee. After giving the students time to describe the differences, remind them that the whiter the material is in an x- ray image, the more dense it is. Some students may be able to use this information to note that the denisty of Stacey s femur is not as uniform as the density of the normal femur. In the normal femur, the edge of the bone is more dense than the center. The density of Stacey s bone, however, is random, resulting in a cloudy appearance. Additionally, there is dense, white bone forming in the soft tissue surrounding the end of Stacey s femur. 4. Form a hypothesis: Do you think that Stacey is experiencing normal growing pains? Student answers will vary. SJCRH; Cancer in the Family by Katherine Ayers 2

3 Part 2 The Diagnosis Stacey and Paul sat in the examination room waiting for the results of the x- ray. At last, Dr. Smith returned. Based on the results of the x- ray, Dr. Smith began, I suspect that Stacey may have osteosarcoma, a cancer of the bone. I am referring Stacey to St. Jude Children s Research Hospital for further evaluation. Cancer! Stacey exclaimed. Tears began to swell in her eyes as Paul put his arm around her to comfort her. What exactly is osteosarcoma? Paul asked. How likely is it for someone this young to develop cancer? I thought cancer was more common in older people. Bones are hard, calcified structures that provide our bodies with structural support and provide a framework our muscles can use to make movement possible, Dr. Smith explained. They are made of three types of cells: osteoblasts, osteoclasts, and osteocytes. Figure 1: Bone Anatomy Osteoblasts help build up bones by forming the bone matrix (the connective tissue and minerals that give bone its strength), while osteoclasts break down bone matrix to prevent too much of it from building up, and they help bones keep their proper shape. As osteoblasts age, they become fixed within the bone matrix and are referred to as osteocytes. SJCRH; Cancer in the Family by Katherine Ayers 3

4 Cancer in the Family In patients with osteosarcoma, he continued, the osteoblasts in the bone begin to grow and divide out of control and produce a weaker bone matrix called an osteoid than the osteoblasts in normal bone tissue. Figure 2: Micrograph of Osteosarcoma Tissue While osteosarcomas can occur at any age, they are more common in children and young adults. Teens are, in fact, the most commonly affected age group. In these cases, osteosarcomas tend to develop in areas of the bone that are growing quickly due to normal growth and development, such as the ends of long bones like in Stacey s case. SJCRH; Cancer in the Family by Katherine Ayers 4

5 Questions: 1. Describe the function of each cell type found in the bone. a. Osteoblast: build up bones by forming the bone matrix b. Osteoclasts: break down bone matrix to prevent too much of it from building up, and they help bones keep their proper shape. 2. What is osteosarcoma? Osteosarcoma is a cancer of the bone in which the osteoblasts begin to grow and divide out of control. 3. Why do you think that Dr. Smith initial suspects that Stacey is simply suffering from growing pains? Students should be able to pull data from the text to explain that Dr. Smith initially suspects growing pains due to Stacey s age. Stacey is 12 years old, and it is common for children at that age to experience mild pain in their joints as the bodies grow and develop into adulthood. Many of the symptoms associated with osteosarcomas are similar those felt during normal growth. 4. At St. Jude, Stacey undergoes several diagnostic tests, including a PET (positron emitting topography) scan. During the PET scan, Stacey is injected with fluorodeoxyglucose, a radio labeled form of glucose. Areas with a high concentration of radiolabeled molecules will become visible on a PET scan image. a. Which cellular process involves glucose? Depending on your classroom curriculum, students may or may not know that glucose is required for cellular respiration. If they are not familiar with this process, this is an excellent time to introduce the process of cellular respiration to students. If they are familiar with it, this is an excellent opportunity for a quick review! SJCRH; Cancer in the Family by Katherine Ayers 5

6 b. Form a hypothesis: Why do you think that fluorodeoxyglucose is used to identify cancer in the body? Students should be able to combine their answer from 4a with the definition of cancer given in part 2. Cancer cells require more glucose than normal cells to produce the necessary amounts of ATP required for their increased rate of cellular division. Fluorodeoxyglucose is a radiolabeled form of glucose, which means that it will become highly concentrated in cells that are actively going through cellular respiration. This includes cancer cells. 5. Normal cells grow and divide in an orderly way. Cancer is caused by genetic mutations that disrupt cell division and leads to uncontrolled cell growth. These genetic mutations can be either inherited or sporadic. In sporadic cancer, these genetic mutations are caused randomly by environmental factors, such as tobacco and radiation. Such factors are encountered throughout life and act over a long period of time; hence, most sporadic cancers occur in adults. Inherited cancer, on the other hand, is cancer that is caused by a mutation that is passed down from parent to offspring. In these individuals, the gene mutation is in every cell of their body, which puts them at a higher risk for developing cancer. Individuals with an inherited predisposition for cancer tend to develop cancer at a younger age than those with sporadic cancer. A family pedigree is a useful tool for determining if an individual has an inherited cancer. Use Stacey s family health history to create Stacey s family pedigree. Stacey s Family History Stacey Ray lives with her mom (Maria Ray; age 39), sister (Angela Ray; age 18), brother (Charles Ray; age 13), and step- father (Paul Jones; age 42). Stacey s mom was diagnosed with breast cancer at age 31. Stacey s brother has mild developmental delays. Stacey s mother has a twin brother (Ben Gordon) and a younger sister (Sarah Gordon; age 35). Neither have any significant medical conditions. Stacey s maternal grandfather (Jerry Gordon) was diagnosed with brain cancer at age 60 and passed away at age 62. Stacey s maternal grandmother (Alice Gordon; age 71) is still living. Stacey s father (Steven Ray; age 41) has an older sister (Veronica Smith; age 43) with no significant medical conditions. Stacey s paternal grandmother (Helen Ray; age 70) and grandfather (Steven Ray; age 72) are still living with no significant medical conditions. SJCRH; Cancer in the Family by Katherine Ayers 6

7 Pass out the How to Make a Family Pedigree worksheet and review with the students the general guidelines and symbols used to generate a family pedigree. Once you have reviewed the guidelines, have students work in groups or independently to create Stacey s family pedigree. Final pedigree should look similar to the example below. Based on Stacey s family pedigree, do you think she has sporadic or inherited cancer? Student responses will vary. SJCRH; Cancer in the Family by Katherine Ayers 7

8 Part 3 Li- Fraumeni Syndrome After analyzing Stacey s family pedigree, she and her family are referred for genetic counseling. At the counseling center they meet Lauren, a genetic counselor. A genetic counselor is a trained professional who helps patients understand and adapt to the medical, psychological, and familial implications of genetic contributions to disease. Based on the age and type of cancer that Stacey has and the history of cancer in the family, we would like to test Stacey for a rare genetic disorder called Li- Fraumeni Syndrome, Lauren said. I don t understand, said Stacey. My mom and I had different types of cancer. How can our cancers possibly be related? Good question. Li- Fraumeni Syndrome is caused by inherited mutations to the TP53 gene, Lauren explained. Genes carry important information that tell our body s cells how to function. The TP53 gene controls how cells grow and divide. One of its main jobs is to keep cancers from forming, she continued. Normally, your cells contain two working copies of TP53 one from mom and one from dad. Cells in individuals with Li- Fraumeni syndrome, however, contain a copy of the TP53 gene that is damaged and no longer works properly. If the second copy also becomes damaged, this can lead to cancer. The type of cells that becomes damaged determines the type of cancer that develops. A genetic test will tell us if Stacey has a damaged TP53 gene. The most common areas of the body affected by Li- Fraumeni syndrome include the brain, breasts, bone, and blood, she explained. What is the benefit of having the test? asked Stacey s mom. Individuals with Li- Fraumeni syndrome are more likely to develop multiple cancers, Lauren explained. Since it is difficult to know which type of cancer will develop and exactly when these cancers will occur, she continued, it is recommended that individuals with Li- Fraumeni receive yearly cancer screenings to try and catch the cancer at the earliest and most treatable stage. Stacey s family is conflicted. Her mother wants her to have the test, but her sister does not. Stacey is unsure about what to do. SJCRH; Cancer in the Family by Katherine Ayers 8

9 Questions: 1. What are some of the benefits associated with genetic screening? Student responses will vary, but may include: Test results can provide a sense of relief from uncertainty and help people make informed decisions about managing their health care. Test results can help make informed decisions when considering having children. 2. What are some of the risks associated with genetic screening? Student responses will vary, but may include: Feelings of guilt. Many parents may feel guilty for passing down damaged genes to their child. Sometimes siblings of individuals who carry damaged genes may experience survivor guilt, which means they feel guilty for not inheriting the damaged gene. Individuals with an inherited risk factor may find themselves paralyzed by fear of the increased risk of developing cancer. Individuals may worry that their health insurance plan will drop their coverage due to the cost of intense screening required for patients with an increased risk of developing cancer. 3. If you were Stacey, would you want genetic testing? Answers will vary. SJCRH; Cancer in the Family by Katherine Ayers 9