Cancer: Cell division gone wrong

Checkpoints in cell cycle Is the DNA fully replicated? Is the DNA damaged? Are there enough nutrients to support cell growth? Monitored by specialized proteins which send messages to nucleus to cell what to do

A Basic Definition Cancer is defined as: Disease caused by of defective cells. Disease caused by uncontrolled growth and division of defective cells. daughter cells continue this destructive cell reproduction cycle daughter cells continue this destructive cell reproduction cycle

Cell Growth Rates and Cancer Cancer occurs when: Cancer occurs when: –Despite messages to STOP, a defective cell continues to grow and divide -a tumour is a lump of defective cells that develops

The Two Types of Tumours 1. Benign Tumours 2. Malignant Tumours

1. Benign Tumours Noncancerous lumps Noncancerous lumps Only harmful if the lumps physically crowd nearby tissues Only harmful if the lumps physically crowd nearby tissues

2. Malignant Tumours Cancerous Cancerous Interfere with the regular functioning of surrounding cells and tissues Interfere with the regular functioning of surrounding cells and tissues May lead to metastasis May lead to metastasis metastasis: occurs when malignant tumour cells break off and form a secondary tumour elsewhere in the body metastasis: occurs when malignant tumour cells break off and form a secondary tumour elsewhere in the body eg. Renal (kidney) cancer

Why is metastasis dangerous? Metastatic tumours may spread to vital areas (blood, lungs etc..) and resulting in more severe health problems Metastatic tumours may spread to vital areas (blood, lungs etc..) and resulting in more severe health problems Multiple locations of cancer are more difficult to treat. Multiple locations of cancer are more difficult to treat. Cancer cannot Cancer cannot spread without a network of blood vessel to support its growth Image from:

What causes of Cancer? There are three general causes of cancer Mutations Caused by: 1. Random Error Mutation during DNA replication 2. Carcinogens 3. Genes (Oncogenes)

Random Error Mutations as a cause for Cancer Errors in DNA duplication may occur during cell division Errors in DNA duplication may occur during cell division Usually, harmful mutations cause the cell to self-destruct or refrain from dividing. Usually, harmful mutations cause the cell to self-destruct or refrain from dividing. When does DNA duplication occur? S phase of cell cycle right before cell division

Carcinogens Environmental factors that cause mutations in DNA Environmental factors that cause mutations in DNA For example: For example: 1. Tobacco smoke

Carcinogens Environmental factors that cause mutations in DNA Environmental factors that cause mutations in DNA For example: For example: 2. Radiation Such as UV rays (sun/tanning beds)

Carcinogens Environmental factors that cause mutations in DNA Environmental factors that cause mutations in DNA For example: For example: 3. Chemicals like BPA (bisphenol A)

Carcinogens Environmental factors that cause mutations in DNA Environmental factors that cause mutations in DNA For example: For example: 4. Viruses (HPV- human papillomavirus can stay in the body and lead to cervical cancer )

Cause of Cancer (Cont.): Oncogenes Defective genes (due to mutations) are passed down from one generation to another Defective genes (due to mutations) are passed down from one generation to another

Oncogenes Family history can indicate presence of oncogenes Family history can indicate presence of oncogenes (Oncology is the study of cancer) (Oncology is the study of cancer) Examples of cancer that tend to run in famillies: Examples of cancer that tend to run in famillies: breast cancer & colon cancer

Different Kinds of Cancer Lung Breast (women) Colon Bladder Prostate (men) Some common sarcomas: Fat Bone Muscle Lymphomas: Lymph nodes Leukemias: Bloodstream Some common carcinomas:

cancer.ca/en/just-the- facts/symptoms/ Breast cancer   Colon cancer Examples of cancer types

Which is the healthy lung? Which cancerous? Healthy Cancerous

Smoking as a cause for Cancer 9 out of 10 cases of lung cancer in Canada are a result of smoking 9 out of 10 cases of lung cancer in Canada are a result of smoking Lung cancer is the most common type of cancer in Canadians over 40 Lung cancer is the most common type of cancer in Canadians over 40 Can you explain why cigarettes are so expensive and why many Canadian bars/clubs are smoke- free? Can you explain why cigarettes are so expensive and why many Canadian bars/clubs are smoke- free?

Population-Based Studies CANADA: Leukemia Regions of Highest Incidence BRAZIL: Cervical cancer U.S.: Colon cancer AUSTRALIA: Skin cancer CHINA: Liver cancer U.K.: Lung cancer JAPAN: Stomach cancer

Detecting Cancer Early detection of cancer is important to prevent metastasis Early detection of cancer is important to prevent metastasis 3 basic screening methods include: 3 basic screening methods include: 1.Genetic testing (for breast or colon cancer) 2.Self-exams (breast or prostate) 3. Medical diagnostics

Medical Diagnostic Tools Endoscopy Endoscopy –Fibre optic cable is inserted into the body cavity to look for suspicious growths –Commonly used to detect colon cancers Observe a colonoscopy AJGPg Pill camera: 4mu0

Medical Diagnostics X-Rays X-Rays –Images used to detect cancer in bones and lung tissue –Mammogram is a specialized x-ray to examine breast tissue

Medical Diagnostics Ultrasound Ultrasound –Sound waves are used to examine soft tissue –Detects cancers in heart or liver tissue  Using ultrasound technology helps avoid the use of harmful X- rays (as in CAT scan)

Medical Diagnostics CT/CAT Scan (computerized axial tomography) CT/CAT Scan (computerized axial tomography) –X-ray images taken from various angles to access hard to see tissues –Often used to detect brain cancer

Medical Diagnostics MRI (magnetic resonance imaging) MRI (magnetic resonance imaging) –Radio waves and magnetic fields generate 3D images with greater detail than CT scans

Medical Diagnostics Examining Cells and Biopsy Examining Cells and Biopsy –Cells are taken via blood samples or surgery and then examined under a microscope –Based on irregular shape and smaller size, cancerous cells can be identified

Conventional Cancer Treatments Cancer is generally treated in three ways: Cancer is generally treated in three ways: 1. Surgery 2. Chemotherapy 3. Radiation

Surgery as Cancer Treatment Cancerous tissue is excised (cut) from the body Cancerous tissue is excised (cut) from the body Benefits: Benefits: Ensures that most of the cancerous cells are physically removed Ensures that most of the cancerous cells are physically removedDisadvantage: Surgery can be risky, especially in the elderly and infirm Surgery can be risky, especially in the elderly and infirm

Chemotherapy Drugs delivered to slow or stop cancer cell division. (May kill cancer cells sometimes) Drugs delivered to slow or stop cancer cell division. (May kill cancer cells sometimes) Benefits: Benefits: Shrinks tumours for later surgical removal or radiation treatment- even small, hard-to- reach tumors Shrinks tumours for later surgical removal or radiation treatment- even small, hard-to- reach tumors Disadvantage: Disadvantage: Suffering from side effects (hair loss, nausea, fatigue) Suffering from side effects (hair loss, nausea, fatigue) May affect healthy cells but they can repair themselves May affect healthy cells but they can repair themselves

Radiation A focused beam of A focused beam of gamma radiation kills or damages cancer cells gamma radiation kills or damages cancer cells Benefits: Benefits: Can precisely target even small tumours Can precisely target even small tumours Disadvantage: Disadvantage: May cause radiation sickness. Also radiation exposure can potentially cause other cancers. May cause radiation sickness. Also radiation exposure can potentially cause other cancers.

Recent advancement

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