[Combined radiotherapy and chemotherapy: pulmonary side effects (author's transl)]

Systemic chemotherapy and lung irradiation have very similar effects on lung tissue. Several mechanisms are involved, mainly: --cytotoxic effects on lung cells (type II pneumocytes, capillary endothelial cells, and connective tissue); --enhancement of infection; --hypersensitivity and auto-immune phenomena. Acute pneumonitis or chronic lung sclerosis develops which may or may not be compatible with life, depending on the lung volume involved and the clinical course. These effects are dose dependent for radiotherapy, and for most of the chemotherapeutic drugs. In some cases however, the dose-effect relationship is not clear, especially with some drugs such as methotrexate, and sometimes with radiotherapy even when it can be assumed that there is no mistake in dose calculation. It must be stressed that we will lack basic knowledge on the pharmacokinetics and actual concentration of drugs in lung tissue. Additive or supra-additive effects are likely when chemotherapy is combined with lung irradiation, but current relevant data does not allow any firm conclusions to be drawn on the quantitative changes resulting from the association. Prevention of lung complications is however possible if the tolerance doses and the optimal distribution of each agent with time are respected. Combined lung irradiation and bleomycin administration must be avoided.