Blastomogenic Effect of Radiation

biological effect of ionizing radiation (such as X-rays, gamma rays, and protons) and nonionizing (ultraviolet) radiation and streams of protons, neutrons, and other particles, which cause the formation of tumors of various tissues. The German scientist K. Frieben first described skin cancer in humans after X-ray irradiation in 1902; later, information appeared about the development of cancer in persons subjected to the effects of radiation in high dosages as a result of their occupational activity (for instance, uranium miners), after atomic explosions (Marshall Islands, Hiroshima, Nagasaki), and through other causes. As a rule, tumors appear on the parts of the body subjected to the most intense radiation and, in the event of entry or special injection of radioactive isotopes, at the foci of their accumulation (deposition). They also appear in tissues that lie in the path of ionizing particles. Ultraviolet radiation, which is intensively absorbed by the surface tissues of the body, may cause formation of benign tumors (for example, papillomas) and malignant tumors (sarcomas, cancers) of the skin and subcutaneous tissue; ultraviolet rays with long waves around 260 nanometers (2,600 angstroms) have the greatest capacity to cause formation of tumors.

When the body is affected by radiation from radioactive isotopes, which are selectively deposited in the bones (⁹⁰Sr, ⁸⁹Sr, ¹⁴⁰Ba, ²²⁶Ra, ⁴⁵Ca, ⁹¹I), tumors of the bone tissue and of organs enclosed in the bone capsule (hematopoietic tissue, hypophysis) or topographically close to it (mucosa of the buccal cavity, antrum of Highmore) develop. Isotopes which selectively accumulate in the liver and skeleton (¹⁴⁴Ce, ¹⁴⁰La, ¹⁴⁷Pm, ²²⁸Th, ²³⁹Pu, ²⁴¹Am, ¹⁹⁸Au) may cause tumors of bones, liver, and endocrines, and more rarely of kidneys, sex organs, stomach, and the large intestine. Isotopes which are distributed evenly in the body (⁹⁵Nb, ¹⁹⁵Cs, ²¹⁰Po, ¹⁰⁶Ru), when injected parenterally, may cause formation of tumors of epithelial, connective, and other tissues, just as does external irradiation (gamma rays, neutrons, protons). Isotopes that accumulate in the thyroid gland sometimes foster the formation of tumors of the thyroid, parathyroids, and hypophysis.

The blastomogenic effect of radiation from radioactive isotopes which are well absorbed by the body (⁸⁹Sr, ⁹⁰Sr, ¹³⁷Cs, ¹³¹J, ¹⁴⁰Ba, ²²⁶Ra) does not depend on their path of entry, whereas the blastomogenic effect of radiation from poorly assimilated isotopes is entirely determined by their path of entry and their site of accumulation in the body. Thus, in experiments on animals, when ¹⁴⁴Ce was introduced by mouth, tumors of the gastrointestinal tract developed; when it was inhaled, tumors of the lungs; and when injected subcutaneously, tumors of the skin, subcutaneous tissue, and bones.

The genesis and development of tumors and their clinical manifestations and treatment depend on the type of radiation that caused the formation of the tumor, its duration, localization, and dosage.