Abstract

Title

lung-perfusion-spect contribution in lung cancer radiotherapy planning process

Authors

Simone Baroni1, Italo Dell'Oca2, Roberta Tummineri2, Ariadna Sanchez Galvan3, Fulvio Borroni2, Stefano Lorenzo Villa3, Giuseppina Mandurino3, Pietro Pacifico3, Anna Chiara2, Marcella Pasetti2, Najla Slim2, Emilia Giovanna Vanoli4, Antonella Del Vecchio5, Stefano Arcangeli6, Nadia Gisella Di Muzio7

Authors Affiliations

1IRCCS San Raffaele Scientific Institute, University of Milano-Bicocca, Radiadion Oncology, Milan, Italy; 2IRCCS San Raffaele Scientific Institute, Radiation Oncology, Milan, Italy; 3IRCCS San Raffaele Scientific Institute, University of Milano-Bicocca, Radiation Oncology, Milan, Italy; 4IRCCS San Raffaele Scientific Institute, Nuclear Medicine, Milan, Italy; 5IRCCS San Raffaele Scientific Institute, Medical Physics, Milan, Italy; 6University of Milano-Bicocca, Radiation Oncology, Milan, Italy; 7IRCCS San Raffaele Scientific Institute, Vita e Salute University, Radiation Oncology, Milan, Italy

Purpose or Objective

Aims: Lung cancer radiotherapy (RT) is associated with potential risk of serious lung injury due to vascular damage. Lung Perfusion can be considered a new parameter to avoid lung toxicity in RT treatment. The inclusion of Lung Perfusion SPECT (L-P-SPECT) information in the planning process could be useful to better spare normal functional lung tissue (FLT) switching from an anatomical to functional base planning.

Materials and Methods

Methods: From March 2017 to December 2018, 41 patients (pts) (16 women, 25 men) with lung cancer and 47 lesions were treated with Tomotherapy (Accuray Inc, Madison, WI; TT). Thirty-eight pts had I-IIIB stage NSCLC (26 adenocarcinoma (adk), 8 squamous cell carcinoma, 1 Large cell carcinoma, 3 PET+ lesions NOS) and 3 pts had lung metastasis; 28 pts had central cancer whereas 13 pts had periferic lesion. All pts underwent L-P-SPECT and PET before TT. According to the literature, FLT was defined as two volumes with a cut-off of 20% (T20) and 30% (T30) perfusion threshold. Median PTV was 174 cc (25cc-567cc), median BTV was 11 cc (1cc-175cc). In 21 pts (51%) PTV also included mediastinum. V5, V10, V20 and mean dose were evaluated for whole and unilateral lung considering parameters of T20, T30. 23 pts (56%) were treated with conventional fractionation, median delivered dose was 60 Gy (60-70Gy) (1,8-2,0 Gy/fr); 18 pts (44%) received hypofractionated TT, median delivered dose was 60 Gy (2.65-9 Gy/fr in 6-25 fr). Toxicity was assessed by CTCAE 4.0 criteria.

Results

Results: 34 pts (83%) showed G0 acute toxicity; 5 (12%) pts reported G1-G2 toxicity (cough 68% and dyspnea 62%). Two chemo pretreated pts (5%) (1: CBDA + Pemetrexed 1: CDDP) had G3 acute toxicity (bacterial pneumonia) resolved with antibiotic drugs. A G3 late toxicity (bilateral interstitial pneumonia) was registered six months after the end of TT, probably related to immunotherapy started 4 months before. V5, V10, V20, mean dose were similar in FLT and in whole lung.

Conclusion

Conclusions: Despite more than half of pts received the radiation on mediastinum and despite the median PTV volume was considerable (174cc) we registered only one G3 late lung toxicity. In our experience, L-P-SPECT can be included in the planning process in order to reduce significantly lung toxicity. The next step will be try to find a specific constraint for FLT allowing the full implementation in the plan optimization together with respiratory function tests.