cancer strike people others new research shows random changes mistakes dna cells dividing cause nearly cancers humans changes neither caused international factors like smoking exposure harmful chemicals hereditary factors chance events occurring molecular plane words cancer tap upends prevailing wisdom cancer for the most part lifestyle related disease caused external environmental factors like smoking harmful chemicals conditions like obesity valid important risk increasing factors random encounter may literal driver one goes new study involved statistical analysis cancer data countries including india defend billion people half worldwide universe done scientist johns hopkins kimmel cancer center baltimore us published peer look back journal science march bodies grow constant part cells starting foremost cubicle formed nuclear fusion manly sperm cell female testicle every fourth dimension cell divides deuce genetic code carrying dna copied scientists say mistakes occur copying process accumulate time ultimately cause cancer copying mistakes potent source cancer mutations historically scientifically undervalued new work provides first estimate fraction mutations caused mistakes said paper lead author cristian researchers studied genus cancer types estimated genus cancer mutations result copying errors attributed lifestyle environmental factors remaining inherited found potent correlation cancer incidence normal prison cell divisions among cancer types disregardless countries environment stage economic means lifestyle constituent like fume exposure toxic chemicals also important factors causing nearly third cancers need continue encourage people avoid environmental agents lifestyles increase risk developing cancer mutations bert vogelstein cancer patients across world shown approximately cancers prevented quash insalubrious environments lifestyle work explains crab known strike people follow rules healthy dwell nonsmoker healthy diet salubrious weight little exposure known carcinogens family history disease dissimilar types cancers different origins researchers found example pancreatic cancers due random dna copying errors environmental factors smoking remaining heredity cancer type prostate brain bone mutations due random copying cancer likely caused environmental factors mostly smoking mutations due smoke due desoxyribonucleic acid copying errors inherited factors negligible role