Cancer of the prostate in men and of the breast in women can be greatly relieved by the removal of the testes and ovaries, respectively, in these patients, or by the removal of adrenal glands which are a secondary source of sex hormones in both sexes. Besides this, administration of counter-hormones (estrogens in males and androgens in females) in such cases also effects a marked improvement.
Environmental factors described above do not lead to cancer in all those exposed to them. So it seems, that something is there in the person to make him susceptible to getting it.