ESTRO 2022

Session Item

Applications of ion beam treatment planning

Session Code: 6030

Session Type: Poster (digital)

Track: Physics

Feasibility of acute hematologic toxicity model-based patient selection for proton beam therapy

Peilin Liu, China

Presentation Number: PO-1505

Abstract

Abstract Title:

Feasibility of acute hematologic toxicity model-based patient selection for proton beam therapy

Authors:

Peilin Liu¹, Xi Cao¹, Xian-shu Gao¹, Shiyu Shang², Jiayu Liu¹, Zishen Wang³, Xuanfeng Ding⁴

¹Peking University First Hospital, Department of Radiation Oncology, Beijing, China; ²Hebei North University, Oncology, Zhangjiakou, China; ³Hebei Yizhou Tumor Hospital, Department of Radiation Oncology, Zhuozhou, China; ⁴Beaumont Health, Proton Beam Therapy Center, Department of Radiation Oncology, Royal Oak，MI, USA

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Purpose or Objective

To investigate the potential clinical benefit of utilizing IMPT to reduce acute hematologic toxicity for locally advanced non-small cell lung cancer (NSCLC) patients and explore the feasibility of a model-based patient selection approach via the normal tissue complication probability (NTCP).

Material and Methods

Twenty patients with locally advanced NSCLC were enrolled.[ld1] Volumetric modulated arc photon therapy (VMAT) and intensity-modulated proton therapy (IMPT) plans were generated with a prescription dose of 60 Gy in 30 fractions. A wide range of cases with varied tumor size, location, stations of metastatic lymph nodes were selected to represent the general cancer group. Contouring and treatment planning followed RTOG-1308 protocol. Doses to bone marrow (BM) and other organ-at-risks were compared. Risk of grade ≥ 3 acute hematologic toxicity (HT3+) were calculated based on NTCP model and patients with reduction on NTCP of HT3+ (△NTCP_HT3+) ≥ 10% were considered to 'significantly benefit from proton therapy.'

Results

Dose to the BM, the lung, the heart, the esophagus and the spinal cord was significantly reduced via IMPT compared to VMAT. Tumor distance to thoracic vertebrae bodies (TVB) was significantly associated with > 10% △NTCP_HT3+ from IMPT to VMAT. For the patients with tumor distance ≤ 0.7 cm to TVB, the absolute reduction of dose (mean, V30 and V40) to BM was significantly lower than that in patients with tumor distance > 0.7 cm.

Figure.1 Possibility of HT3+ in 20 patients

Conclusion

IMPT reduced HT3+ compared to VMAT by reducing dose to the thoracic BM in NSCLC patients. Patients with tumor distance ≤ 0.7 cm to TVB are likely to benefit most from proton over photon therapy