Pulmonary toxicity generated from radiotherapeutic treatment of thoracic malignancies

Abstract

Radiation-induced lung injury (RILI) remains a major obstacle for thoracic radiotherapy for the treatment of lung cancer, esophageal cancer and lymphoma. It is the principal dose-limiting complication, and can markedly impair the therapeutic ratio as well as a patient's quality of life. The current review presents the relevant concepts associated with RILI, including the pathogenic mechanisms and the potential treatment strategies, so as to achieve a general understanding of this issue. RILI comprises an acute radiation pneumonitis phase and subsequent late lung fibrosis. The established assessment criteria are clinical manifestations, imaging changes and the necessity for medical assistance. Risk factors are also considered in order to optimize treatment planning. Due to the underlying molecular mechanisms of RILI, the present review also discusses several targeted pharmacological approaches for its treatment, as well as corticosteroid therapy.

Keywords: lung fibrosis; radiation pneumonitis; radiotherapy; thoracic malignancy.

Figure 1.

Computed tomography images (A, before radiotherapy; B, post radiotherapy) of a 63-year-old woman with esophageal cancer. Following radiation of ≤59.4 Gy, certain imaging changes were apparent in panel B, including scattered areas of patchy density in the lung (noted by the black arrow in panel B). The clinical manifestations of this patient were mild, with only a dry cough reported.

Figure 2.

Computed tomography images of a 58-year-old man with lung cancer (A, before radiotherapy; B, post radiotherapy). Although the V₂₀ (% volume of lung that received ≥20 Gy radiation) for the whole lung was 23%, typical imaging findings of RP were visible, including patchy infiltration and density (noted by the black arrows in panel B). This patient presented with severe symptoms, including a prolonged high fever with yellow mucus production, which were insensitive to standard antibacterial agents.