Cancer's 10 Hallmarks

Cancer is a leading cause of disease-related death. Environmental effects and aging accumulate damage (mutations) in genes controlling cell proliferation and relationships, leading to cancer. Despite differing causes, the common outcome is uncontrolled cell proliferation.

Cancer is not one disease; it has over 120 types. Developing effective treatments depends on identifying its fundamental characteristicsas a requirement.

Scientists have identified 10 hallmarks of cancer.

1. Having its own growth factors: Normal cells need external growth factors to multiply. Mutations enable cancer cells to produce their own. For example, in HER2-positive breast cancer, increased HER2 growth factors or mutations in receptors binding HER2 cause a continuous proliferation signal to reach the cell.
2. Evading growth-inhibiting factors: Normal cells stop growing after reaching a certain capacity in response to external signals, maintaining internal balance called homeostasis. Cancer cells evade this by disrupting receptors receiving growth-inhibiting signals.
3. Escaping the immune system: Immunity recognizes and destroys foreign substances. Normal cells carry surface proteins marking them as “friends”. Cancer cells also carry these proteins and learn to become invisible to immunity through this mechanism.
4. Continuous division: Cells other than stem cells divide a limited number of times, then enter an aging phase called senescence . This is caused by telomere shortening . Genes lie in chromosomes, whose ends contain sequences called “telomeres”. Telomeres decrease with each division, protecting genes. Cancer cells increase the activity of “telomerase” enzymes to prevent shortening, gaining unlimited proliferative capacity.
5. Cancer-promoting inflammation: The tumor environment contains cancer cells and inflammation-related immune cells. These increase growth factors and enzymes, creating conditions favoring vessel formation and spread. They also produce reactive oxygen radicals, damaging DNA and causing cancer. 
6. Migration to other tissues and organs (Invasion or Metastasis): Normal cells generally remain in place. Cancer cells migrate after reaching a certain growth level. This is called metastasis . Metastases account for % 90 of cancer deaths. Damage to genes enabling cells to attach to one another or tissue triggers metastasis. 
7. Angiogenesis (new vessel formation): Normal cells need blood vessels for nutrients and oxygen, but vessel formation is limited in adults. Rapidly dividing cancer cells need large nutrient and oxygen supplies and therefore can form vessels. 
8. Gene mutations (errors): Accumulated DNA damage is the main cause of cancer. Loss of DNA repair enzyme function also promotes increasing genetic disruption. 
9. Evading cell death: When normal cells suffer DNA damage, tumor suppressor genes stop proliferation and initiate repair. Irreparably damaged cells are eliminated through programmed death (apoptosis). Cancer cells possess mechanisms resisting this.
10. Changing energy metabolism: Rapidly dividing cancer cells need much energy. They continually use glucose to produce energy regardless of oxygen availability, known as the “Warburg effect”.

Advancing cancer research discovers new characteristics daily. We plan to discuss treatments targeting these in our next article.