Although
radiotherapy improves locoregional control and survival in patients with
non-small-cell lung cancer,
radiation pneumonitis is a common treatment-related toxicity. Many pulmonary function tests are not significantly altered by pulmonary toxicity of irradiation, but reductions in D(L(CO)), the diffusing capacity of
carbon monoxide, are more commonly associated with
pneumonitis. Several patient-specific factors (e.g. age, smoking history,
tumor location, performance score, gender) and treatment-specific factors (e.g.
chemotherapy regimen and dose) have been proposed as potential predictors of the risk of
radiation pneumonitis, but these have not been consistently demonstrated across different studies. The risk of
radiation pneumonitis also seems to increase as the cumulative dose of radiation to normal lung tissue increases, as measured by dose-volume histograms. However, controversy persists about which dosimetric parameter optimally predicts the risk of
radiation pneumonitis, and whether the volume of lung or the dose of radiation is more important. Radiation oncologists ought to consider these dosimetric factors when designing
radiation treatment plans for all patients who receive thoracic
radiotherapy. Newer
radiotherapy techniques and technologies may reduce the exposure of normal lung to irradiation. Several medications have also been evaluated for their ability to reduce
radiation pneumonitis in animals and humans, including
corticosteroids,
amifostine,
ACE inhibitors or
angiotensin II type 1 receptor blockers,
pentoxifylline,
melatonin,
carvedilol, and
manganese superoxide dismutase-plasmid/
liposome. Additional research is warranted to determine the efficacy of these medications and identify nonpharmacologic strategies to predict and prevent
radiation pneumonitis.