Medical Genetics Therefore the cancer cell arises and progresses once out of a possible 1014 cellular targets. That only happens in 1 in 3 people. Even then it usually takes 60 or 70 years to occurMedical Genetics Therefore, the cancer cell arises and progresses once out of a possible 1014 cellular targets. That only happens in 1 in 3 people. Even then it usually takes 60 or 70 years to occur