Best treatment for keloid scars

Howcan keloid scars be treated ?
there are several ways that can be used to treat these types of scars one of then in by injection of corticosteroid inside the scar that helps shrinking it , and sometimes doctors apply pressure for long time to be removed gradually , another way is used that called cryotherapy , and finally Laser or surgical removal of the scar and it doesn't take time 
What are the causes of those scars :

• tattos 
• severs acne 
• infected acne 
• sugical scar 
• cut wound
• Piercings 

Advice: 
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