6a Cancer - Diagnosis & Treatment (1)

Understanding Cancer and Cell Division

1. Introduction to Cancer

  • Cancer arises from uncontrollable cell division, leading to harmful tumors.

  • Mitosis plays a key role in cell division; cells need to replicate DNA before division.

2. Cell Cycle Checkpoints

  • The cell cycle has critical checkpoints to ensure proper cell division.

A. Types of Checkpoints

  • G1 Checkpoint: Checks for cell size, nutrients, and DNA damage before DNA synthesis.

  • S Phase: Replication of DNA occurs here.

  • G2 Checkpoint: Ensures that DNA has been replicated correctly and checks cell size.

  • Metaphase Checkpoint: Assesses chromosome spindle attachment before anaphase.

3. Functioning of Checkpoints

  • If damage is detected at any checkpoint, the cell will attempt to repair it. If unrepaired, the cell may be destroyed.

  • Mutated cells may have altered DNA, which can impair the function of checkpoints, leading to cancer development.

Mutations

1. Definition and Effects of Mutations

  • A mutation is a random change in DNA.

A. Types of Mutations

  • Harmful: Interferes with cellular functions.

  • Beneficial: Provides new, useful functions.

  • No Effect: Many DNA regions do not instruct protein synthesis.

2. Causes of Mutations

  • Mutations can arise from various factors including carcinogens, genetics, and lifestyle habits.

  • Carcinogens are environmental agents that may induce cancer.

Cancer Cells vs Normal Cells

1. Characteristics of Normal Cells

  • Divided slowly, eventually die, and are replaced by new cells.

2. Characteristics of Cancer Cells

  • Divide rapidly and uncontrollably.

  • Have prolonged lifespans and can accumulate to form tumors.

  • Exhibit larger, darker nuclei and disorganized arrangements.

Tumors

1. Definition and Types of Tumors

  • Tumors are masses formed by the uncontrolled growth of cancer cells.

A. Benign Tumors

  • Clusters of cells that do not disrupt body functions.

B. Malignant Tumors

  • Interfere with surrounding cell functions; have the potential to metastasize (spread to distant sites).

Detecting Cancer

  • Detection involves various imaging technologies to identify abnormalities in tissues.

1. Imaging Technologies

  • CT Scans: Uses multiple X-rays for comprehensive imaging.

  • X-Rays: Used for examining specific parts like lungs and bones.

  • MRI: Produces detailed 3D images using magnetic fields.

  • Ultrasound: Employs sound waves for soft tissue visualization.

  • PET Scans: Shows metabolic activity using radioactive tracers.

  • Endoscope: Provides direct visual examination of internal structures (e.g., colon).

2. Confirming Diagnosis

  • Tumor samples obtained through biopsy are examined microscopically to determine if the cells are benign or malignant.

Cancer Staging

  • The TNM classification system is used to stage cancer from 0 to IV.

1. Staging Overview

  • Stage 0: Precancerous condition.

  • Stage I: Tumor small, localized.

  • Stages II/III: Tumor larger or metastasized to nearby tissues.

  • Stage IV: Distant spread through lymphatic or blood systems.

Treatments for Cancer

  • Treatment plans are tailored based on the tumor's origin, size, growth rate, and spread.

1. Surgery

  • Involves physically removing the tumor; works well if detected early.

  • Advantages: Potential for complete tumor removal and symptom relief.

  • Disadvantages: Recovery pain, infection risk, and limitations if cancer spreads.

2. Chemotherapy

  • Utilizes drugs to kill or prevent division of cancer cells; can be administered orally or via injection.

  • Advantages: Effective for spread cancers.

  • Disadvantages: Toxicity affecting healthy cells; severe side effects.

3. Radiation Therapy

  • High doses or focused lasers used to damage DNA of cancer cells.

  • Advantages: Effective in targeting tumors.

  • Disadvantages: Potential harm to surrounding healthy cells; various side effects.

4. Immunotherapy

  • Trains the immune system to recognize and fight cancer cells.

  • Advantages: Beneficial when other treatments fail; fewer side effects.

  • Disadvantages: May cause severe allergic reactions and flu-like symptoms.

5. Treatment Timeline

  • Radiation typically begins a few weeks after surgery unless combined with chemotherapy.

  • Adding immunotherapy after chemotherapy may enhance overall survival rates.