Cancer and the Cell Cycle Small cell shows a healthy white blood cell and the big cell shows and in invading cancer cell.

Cell Cycle Checkpoints There are proteins that send messages to the nucleus, telling the cell whether or not to divide A cell should remain in interphase and NOT divide if: Signals from the surrounding cells tell the cell not to divide There are not enough nutrients to provide for cell growth The DNA within the nucleus has not been replicated (copied) The DNA is damaged If there is too much damage to the DNA, the cell is usually destroyed This is a vital process that keeps organisms healthy

Cell Cycle Gone Wrong… Cancer one or more of the checkpoints fails, so the cell and all of its subsequent daughter cells continue to divide uncontrollably No G0 – division over and over again

Role of Cell Division in Cancer Top = normal cell division Bottom = unregulated cell division and tumour formation Malignant If tumor invades surrounding tissue (cancerous) Benign If tumor has no effect on surrounding tissue (non-cancerous) Apoptosis: A form of cell death in which a programmed sequence of events leads to the elimination of cells without releasing harmful substances into the surrounding area. Apoptosis plays a crucial role in developing and maintaining health by eliminating old cells, unnecessary cells, and unhealthy cells. The human body replaces perhaps a million cells a second. Too little or too much apoptosis plays a role in a great many diseases. When programmed cell death does not work right, cells that should be eliminated may hang around and become immortal. For example, in cancer and leukemia. When apoptosis works overly well, it kills too many cells and inflicts grave tissue damage. This is the case in strokes and neurodegenerative disorders such as Alzheimer, Huntington and Parkinson diseases. Apoptosis is also called programmed cell death or cell suicide. Strictly speaking, the term apoptosis refers only to the structural changes cells go through, and programmed cell death refers to the complete underlying process, but the terms are often used interchangeably. Benign – no effect on surrounding tissue Malignant – invades surrounding tissue Metastatic – cells break away and invade other areas Metastatic If individual cells break away and start a new tumor elsewhere (cancerous) Image from the National Cancer Institute

The vessels of the circulatory and lymphatic systems provide a pipeline for cancer cells to move to other locations in the body through a process called metastasis.

What is Cancer? “Cancer is a group of diseases characterized by uncontrolled growth and spread of abnormal cells. If the spread is not controlled, it can result in death.” - The American Cancer Society Tumours Two types: Benign (non-cancerous) – this is not cancer! Does not spread; it can eventually become malignant in some cases Malignant (cancerous) – this is cancer! Has the potential to spread to other parts of body

Do you know someone personally that has had cancer?

Overall Cancer Incidence and Mortality (death) Trends in U.S. - Includes all sexes! The number of deaths due to cancer has been decreasing since 1990

Canadian Cancer Society Reports… Approximately 83,900 Canadian women will be diagnosed with cancer and an estimated 36,200 women will die of cancer. Approximately 90,000 Canadian men will be diagnosed with cancer and an estimated 40,000 men will die of cancer On average, 3,340 Canadians will be diagnosed with cancer every week. On average, 1,470 Canadians will die of cancer every week. Prostate cancer is the most frequently diagnosed cancer in Ontario, followed by breast cancer and colorectal cancer, respectively. - Includes all

Lung Tissue A and C – normal lung tissue --- A = bronchial and C = alveolar. B and D – invaded by cancer cells

Causes of Cancer If errors occur during the replication (copying) of DNA, mutations can result If mutations occur in the DNA that controls cell division, the cells may become cancerous and grow wildly through repeated, uncontrolled mitosis and cytokinesis Some mutations are caused by carcinogens (environmental factors that cause cancer) Some typical carcinogens are: tobacco smoke, radiation (x-rays, UV rays), viruses, and chemicals

Cancer Screening Screening for cancer is done even though there are no symptoms Cancer screening can be done in a number of ways, and is especially important for those who have a family history of cancers Men and women should take responsibility for their health by performing self-tests Other screening tests include a Pap test for women (to check for cervical cancer), a blood test for colon cancer and regular skin checks

Reducing Your Risk of Cancer Many factors can increase your risk of getting cancer: Personal and family medical history Carcinogens in your environment Lifestyle choices (only one you control to have a big impact on your likelihood of getting cancer) Avoid tobacco smoke Healthy diet (lots of fruit and vegetables, less fatty meat) Certain cancer ‘super foods’ have been identified that contain substances that help your body protect itself from cancers (see figure 4 on page 51)

Diagnosing Cancer The earlier cancer is diagnosed, the better the chances of it being successfully treated If cancer is suspected, doctors will order medical tests to investigate further: Imaging technologies (include endoscope, x-ray, ultrasound, CT scan and MRI) – see figures 6 – 10 on pages 52 and 53 Examining cells – look at suspected cancer cells under microscope (such as blood cell samples or a biopsy of tumour cells)

Treatment for Cancer Radiation Chemotherapy Surgery There are currently three conventional methods of treating cancer: Radiation Uses high-energy rays to kill cancer cells A large machine directs radiation at the body Chemotherapy Uses anti-cancer drugs to kill cancer cells (also kills healthy cells) Surgery physical removal of all cancerous tissue

Trends in Five-year Relative Survival (%)* Rates, US, 1975-2004 Site 1975-1977 1984-1986 1996-2004 Breast (female) 75 79 89 Lung 13 16 Ovary 37 40 46 Prostate 69 76 99 Colon 52 59 65 From American Cancer Society Estimates the prognosis of the disease Relative survival: number of people with the disease who are alive after 5 years divided by the number of the of comparable people in the general population also alive after 5 years

Survival Data according to Canadian Cancer Society Based on 2002-2004 estimates, 62% of people are expected to survive for 5 years after their cancer diagnosis compared to the general population of the same age and sex. Survival rates differ according to the type of cancer One in 7 men will develop prostate cancer during his lifetime (the risk is highest after age 60) and one in 27 will die of it One in 9 women is expected to develop breast cancer during her lifetime and one in 28 will die of it One in 11 men is expected to develop lung cancer during his lifetime and one in 13 will die of it.  One in 16 women is expected to develop lung cancer during her lifetime and one in 18 is expected to die of it.

Inquiry: Does the Patient Have Cancer? Title Purpose Observations: Graph Complete questions #1 to 3 To be handed in before you leave class!

How to Make a Graph Proper title that explains what the graph represents Create a “best line” using a smooth curve Label the x- and y-axes (independent variable on the x and dependent variable on the y) Include units in the axes labels Number the scale on both axes Make sure the entire page is used (large graph) Include a legend when more than one curve is graphed - Note not all points have to be on the line

Follow-up to Cancer & the Cell Cycle For Homework: Define tumor (benign and cancerous), metastasis ‘Check Your Learning’ # 1 – 3, 7, 8 on page 55