Table 3.

Description of Proton Prioritization System (PROPS) Domains

Diagnosis	Certain diagnoses are given priority based on anticipated clinical benefit or department research efforts
Site	Proton therapy offers particular benefits in certain anatomic sites (base of skull, orbit, spine, brain, retroperitoneum, mediastinum, reirradiation situations).
Stage	Proton therapy will provide greater incremental benefit for patients with local or regional cancers than those with metastatic cancer.
Performance status/co-moridity	The purpose of this domain is to capture the influence of performance status and co-morbid conditions on patient prognosis. Patients are grouped into 3 categories: 1) the healthiest patients with few comorbidities and excellent performance status (ECOG 0/1); 2) those in poor health with multiple serious comorbidities and poor performance status (ECOG ≥3); and 3) a middle group between these 2 extremes with moderate comorbidities.
Age	The patient's age at time of treatment.
Urgency	The time sensitivity under which radiation should commence. More urgent cases are prioritized higher. Several situations may require minimal delay in initiating treatment, including: 1) patients with gross disease causing symptoms; 2) diagnoses where medical literature has demonstrated detrimental outcomes associated with delayed or prolonged treatment (e.g. head and neck cancer, cervical cancer); 3) patients who will receive combined modality therapy and whose radiotherapy course must be integrated with a chemotherapy schedule.
Clinical Protocol	Most patients will be enrolled in clinical protocols. Preference will be given to patients who are enrolled in protocols of particular departmental priority.