Cancer is neither hereditary nor familial. It is its very commonness that makes it occasionally seem so. Willis 20 has generalized that most of the 'cancer families' exemplify only the laws of chance. A cancer is for the owner, a part of his or her own flesh and blood. It cannot be attacked with impunity without damaging other normal tissues.
All anticancer agents treat cancer cells in the same manner as they treat all normal cells.
This inseparableness of cancer from normal tissues has rendered cancer radiotherapy 'obsolete' 22 and cancer chemotherapy 'an absolute farce' 22 . The type of cancer that occurs is species specific - of the kidneys in frogs, of the nasal sinuses in dogs, of the eyes in Hereford cattle, breasts in bitches, as leukemia in Scottish terriers, and as melanoma of the skin in grey horses. A predominant involvement of a particular organ or system is seen in the different races of man too, as exemplified by the very high incidence of stomach cancer in the Japanese who, as a compensation, have the lowest incidence of leukemia in the whole world. This varying prevalence is not dependent on the environment. It is the racial or the ethnic genetic constitution which governs the type of cancer in a given population.