Cancer Biology

How normal cells become cancer cells, why tumors spread, and how modern therapies fight back — from cell-cycle switches to CAR-T.

1. Unit 1

   Cell Cycle Control & Checkpoints

   Normal cells divide only when told to, and only when their DNA is intact. Cancer begins when these controls fail.

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   • 1.1Cyclins, CDKs & the Engine of Division2 min · 3 checks
   • 1.2The Restriction Point: Rb and E2F2 min · 3 checks
   • 1.3DNA Damage Checkpoints2 min · 3 checks
2. Unit 2

   Oncogenes & Growth Signaling

   Oncogenes are mutated, overactive versions of normal genes that push cells to grow. One bad copy is enough.

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   • 2.1Proto-oncogenes and How They Turn Bad2 min · 3 checks
   • 2.2Receptor Tyrosine Kinases & the RAS–MAPK Pathway2 min · 3 checks
   • 2.3PI3K–AKT–mTOR and MYC2 min · 3 checks
3. Unit 3

   Tumor Suppressors & Apoptosis

   Tumor suppressors are the brakes. Both copies usually have to fail — and cancer cells also learn to dodge programmed death.

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   • 3.1Knudson's Two-Hit Hypothesis2 min · 3 checks
   • 3.2APC, BRCA and Other Classic Suppressors2 min · 3 checks
   • 3.3Apoptosis and How Cancer Evades It2 min · 3 checks
4. Unit 4

   The Hallmarks of Cancer

   Hanahan and Weinberg distilled cancer into a set of acquired capabilities. These are the common goals every tumor must reach.

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   • 4.1The Hallmark Framework2 min · 3 checks
   • 4.2Replicative Immortality & Telomeres2 min · 3 checks
   • 4.3Metabolic Reprogramming: The Warburg Effect2 min · 3 checks
5. Unit 5

   Angiogenesis, Invasion & Metastasis

   Tumors must build blood supply, break free and colonize distant organs. Metastasis causes about 90% of cancer deaths.

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   • 5.1The Angiogenic Switch2 min · 3 checks
   • 5.2Invasion and the EMT2 min · 3 checks
   • 5.3The Metastatic Cascade2 min · 3 checks
6. Unit 6

   Genomics, Epigenetics & Tumor Evolution

   Tumors evolve. Mutations, chromosome chaos and epigenetic changes generate diversity that selection acts on.

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   • 6.1Mutation Sources and Genomic Instability2 min · 3 checks
   • 6.2Epigenetic Changes in Cancer2 min · 3 checks
   • 6.3Clonal Evolution and Heterogeneity2 min · 3 checks
7. Unit 7

   Cancer Therapy: Targeted & Immune

   From blunt chemotherapy to drugs aimed at single mutations and therapies that re-arm the immune system.

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   • 7.1Chemotherapy and Radiation2 min · 3 checks
   • 7.2Targeted Therapy and Resistance2 min · 3 checks
   • 7.3Immunotherapy2 min · 3 checks