Oxygen effect

Oxygen effect refers to the phenomenon where the radiosensitivity of tissues in the body increases with the presence of oxygen. This effect is particularly significant in radiation therapy, where it is exploited to maximize the damage to cancer cells while minimizing harm to healthy tissues.

Overview

The oxygen effect is a critical factor in the field of radiobiology. It was first observed in the early 20th century, when researchers noted that the presence of oxygen increased the damage caused by ionizing radiation. This is because oxygen, being a potent oxidizing agent, can interact with the DNA damage caused by radiation to create permanent, unrepairable lesions.

Mechanism

The mechanism of the oxygen effect involves the production of reactive oxygen species (ROS) during the process of radiolysis, where water molecules are broken down by radiation. These ROS can then react with the DNA damage sites, converting them into stable, unrepairable lesions. This process is known as fixation of damage.

Clinical significance

In the context of radiation therapy, the oxygen effect is exploited to maximize the damage to cancer cells. This is achieved by delivering the radiation dose at a time when the tumor is well-oxygenated. However, this can be challenging due to the often hypoxic nature of tumors. Various strategies, such as hyperbaric oxygen therapy and the use of radiosensitizers, are employed to overcome this issue.

See also

• Radiobiology
• Radiation therapy
• Hyperbaric oxygen therapy
• Radiosensitizer