F-18-deoxyglucose positron emission tomography (FDG-PET) for the planning of radiotherapy in lung cancer: High impact in patients with atelectasis

Purpose: F-18-deoxyglucose positron emission tomography (FDG-PET) is increa singly applied in the staging of lung cancer (LC). This study analyzes the potential contribution of PET in radiotherapy planning for LC with special respect to tumor-associated atelectasis. Methods and Materials: Thirty-four patients with histologically confirmed L C, who had been examined by PET during pretreatment staging, were included. All were irradiated after CT-based therapy planning with anterior/posterio r (AP) portals encompassing the primary tumor and the mediastinum (CT porta ls, CP). The result of the PET examination was unknown in treatment plannin g. In retrospect, a PET portal (PP) was delineated and compared with the CP . Results: In 12/34 cases, the shape and/or size of the portals were changed, primarily (n = 10) the size of the fields was reduced. The median area of CP was 182 cm(2) versus 167 cm(2) of PP. Seventeen of 34 patients had dys- or atelectasis caused by a central primary tumor. In these cases, differenc es between CP and PP were significantly more frequent than in the other pat ients (8/17 vs. 3/17, p = 0.03). Conclusion: In this retrospective analysis, the information provided by FDG -PET would have contributed to a substantial reduction of the size of radio therapy portals. This applies particularly for patients with tumor-associat ed dys- or atelectasis. (C) 1999 Elsevier Science Inc.