Radiobiological model-based approach to determine the potential of dose-escalated robust intensity-modulated proton radiotherapy in reducing gastrointestinal toxicity in the treatment of locally advanced unresectable pancreatic cancer of the head

Table 4 Normal tissue complication probability (NTCP), Relative risk (RR) ratio, number of patients with ∆NTCP_{IMRT – ro-IMPT} in specific range for gastro-intestinal OARs toxicity

Gastro-intestional OAR	NTCP (%)		P-value IMRT vs. ro-IMPT	Relative risk (RR) ratio (Mean ± S.D)	∆NTCP_{IMRT – ro-IMPT} (n/N)
Gastro-intestional OAR	IMRT (Mean ± S.D)	ro-IMPT (Mean ± S.D)	P-value IMRT vs. ro-IMPT	Relative risk (RR) ratio (Mean ± S.D)	≤5%	> 5 to ≤10%	> 10%
Stomach wall
U/P (Burman et al.)	0.02 ± 0.01%	0.01 ± 0.01%	0.03*	0.16 ± 0.24	9/9	0/9	0/9
GB (Pan et al.)	13.97 ± 5.33%	10.55 ± 4.10%	0.007*	0.81 ± 0.19	6/9	3/9	0/9
Duodenum
GB (Pan et al.)	5.02 ± 0.57%	1.87 ± 0.31%	0.004*	0.37 ± 0.28	9/9	0/9	0/9
Grade ≥ 3 GI toxicity (Holyoake et al.)	3.60 ± 0.54%	3.74 ± 0.24%	0.55	1.1 ± 0.22	9/9	0/9	0/9
Small bowel loops
O/P (Burman et al.)	0.26 ± 0.47%	0.10 ± 0.23%	0.07	0.24 ± 0.22	9/9	0/9	0/9
StoDuo
GB (Pan et al.)	7.81 ± 2.53%	5.67 ± 2.15%	0.008*	0.76 ± 0.22	7/9	2/9	0/9

Abbreviations: IMRT Intensity-modulated radiotherapy, ro-IMPT Robust Intensity-modulated proton therapy, GB Gastric bleed, U/P ulceration/perforation, O/P obstruction/perforation, OAR organ at risk; Relative risk (RR) ratio NTCP_ro-_IMPT/NTCP_IMRT; ∆NTCP_{IMRT – ro-IMPT}, n/N number of patients with specific ∆NTCP range/total number of patient (where N = 9), SD Standard deviation; NTCP derived using parameter from Pan et al., Burman et al., and Holyoake et al.
*Significant (P < 0.05)

ISSN: 1748-717X