CANCER

Levels of Body Organization

• Body tissues work together as part of an organ.
• Organs collaborate to form an organ system.
• Cells are specialized for different organizational levels.
  • Examples of specialized cells:
  • Skin cells
  • Stomach cells
  • Muscle cells
• Cellular functions must be regulated.

The Cell Cycle

• Cells undergo a regulated cycle known as the cell cycle.
• The cell cycle addresses the question of what cells are currently doing.
• Key aspects of cell growth and reproduction:
  • Cells increase in size but multi-cellular organisms grow by creating more cells through division.
  • This process is termed cell reproduction.

Importance of Cell Division

• Organisms grow by making more cells, not individual cell size increase.
• The transition from childhood to adulthood involves cell division.
• Mitosis followed by cytokinesis results in the creation of new body cells.
• Excessive or unregulated cell division can lead to cancer.

Cancer

• Cancer is characterized by uncontrolled cell division leading to tumor growth.
• Cancer cells often struggle to perform normal functions:
  • May fail to communicate with healthy cells.
  • May lose the ability to anchor securely to one another.
  • Some secrete growth hormones, diverting blood vessels and nutrients away from healthy cells.
• Factors contributing to cancer development:
  • Genetic predispositions leading to susceptibility.
  • Environmental factors: toxins, radiation, UV light.
  • These can damage DNA and promote the transformation from normal to cancerous cells.

Tumor Development

• Uncontrolled growth leads to numerous identical cancerous cells.
• Tumors can remain localized or metastasize.

Treatment Developments

• Ongoing advancements in treatments for cancer include:
  • Destroying cancer cells with radiation.
  • Targeted medications like chemotherapy, which focus on dividing cells.

The Cell Cycle Breakdown

• The cell cycle is often depicted as a pie chart, representing two main phases:
  • Interphase: where cells grow, replicate DNA, and perform cellular functions.
  • M phase: where mitosis and cytokinesis occur.

Phases of the Cell Cycle

• Interphase includes three stages:
  1. G1 phase: Cell grows and prepares for DNA replication.
  2. S phase: Synthesis phase where DNA replication occurs.
  3. G2 phase: Growth continues and prepares for mitosis.
• M phase: The phase where mitosis and cytokinesis take place, resulting in cell division.

Checkpoints in the Cell Cycle

• Checkpoints are critical regulatory structures ensuring proper division.
  • G1 checkpoint:
  • verifies cell growth quality, checks for DNA damage.
  • assesses resource adequacy for S phase.
  • G2 checkpoint:
  • verifies DNA replication integrity.
  • checks cell growth and resources before mitosis.
  • M phase checkpoint (metaphase):
  • ensures chromosomes are correctly arranged and attached to spindles prior to separation.

Consequences of Checkpoint Failures

• If a cell fails to meet checkpoint requirements:
  • It may temporarily halt for repairs.
  • Alternatively, it may undergo apoptosis, a programmed cell death.

Regulation of the Cell Cycle

• Proteins play crucial roles in the regulation of the cell cycle:
  • Positive regulators: Allow progression (e.g., cyclins and CDKs).
  • Negative regulators: Inhibit progression (e.g., p53 initiates apoptosis).
• CDK (Cyclin-dependent Kinase):
  • An enzyme that requires binding with cyclin for activation.
  • Cyclin levels fluctuate throughout the cell cycle, aiding progression through different phases.

G0 Phase

• G0 Phase:
  • A resting state where cells perform functions but do not prepare for division.
  • Some cells may enter G0 temporarily; others, like certain neurons, may remain in G0 permanently.

Implications of Cancer Development

• Cancer development results from the breakdown of multiple regulatory checkpoints.
• Normal cells transform into cancerous cells due to damaged gene functions controlling the cycle.
• Oncogenes: Genes that drive cancerous behaviors when expressed.

Contact Inhibition

• Normal cells adhere to contact inhibition, halting further growth upon contact with other cells.
• Cancer cells disregard this mechanism, leading to uncontrolled growth into neighboring tissues.

Treatments for Cancer

• Cancer therapy typically encompasses:
  • Surgery for local tumors.
  • Chemotherapy and radiation to target rapidly dividing cells.
• Combining therapies may improve efficacy.

Chemotherapy Insights

• Two types of cancer drugs:
  • Cell Cycle Specific:
  • These hinder a specific phase of the cell cycle.
  • Cell Cycle Non-specific:
  • These can operate throughout the cell cycle.
• Major concerns include balancing drug effectiveness against the toxicity to normal cells.

Breast Cancer Insights

• Tumor markers facilitate personalized treatment:
  • Examples of crucial tumor markers include estrogen receptors and HER2.
  • Positive receptor status influences treatment choices (e.g., tamoxifen for hormone-sensitive cancers).
• Types of surgical interventions:
  • Biopsy during surgery to assess cancer spread and local lymph nodes status.
  • The importance of imaging for accurate surgery planning.

Radiation Therapy

• Radiation is a localized treatment applied post-lumpectomy to eliminate residual cancerous cells.

Chemotherapy and Side Effects

• Common side effects of chemotherapy include:
  • Nausea and Vomiting: Managed proactively.
  • Anemia: Observed with reduced red blood cell production.
  • Neutropenia: Impaired white blood cell production leading to increased infection risk.
  • Mucositis: Inflammation and ulceration of the mucous membranes.
• For managing side effects, supportive treatments like epoetin stimulate red blood cell formation and mitigate the effects of chemotherapy.

Patient Care During Cancer Treatment

• Close monitoring of lab tests for patient safety and side effects is crucial.
• Encourage hydration, nutrition, and oral hygiene as integral elements of care.
• Emotional support and education about effects of treatment (e.g., loss of hair, body image) enhance overall patient management.
• Management of pain and safety around patients undergoing treatment are critical for improving quality of life and outcomes.