Relationships between dose to the gastro-intestinal tract and patient-reported symptom domains after radiotherapy for localized prostate cancer

Figures & data

Table I. The studied symptoms domains, symptom phrasing, moderate severity cut-off, and related proportions for both cohorts.

Cohort	Symptom domain	Symptom id	Question/symptom	Moderate severity	Proportion (N) ≥ Moderate
DK	Defecation urgency	Q7	Time to defer defecation before toilet visit	6–10 min	0.35 (75)
		Q22	Re-defecate < 1 h after last bowel movement	1–6 times/w	0.12 (25)
		Q23	Immediate toilet visit due to urgency	1–6 times/w	0.17 (37)
	Faecal leakage	Q3	Involuntary leakage solid stools	2–4 times/m	0.05 (11)
		Q12	Incomplete evacuation of stools	1–6 times/w	0.12 (25)
		Q21*	Nocturnal bowel movements	1–6 times/w	0.02 (5)
		Q22	Re-defecate < 1 h after last bowel movement	1–6 times/w	0.18 (38)
	Pain	Q10*	Pain at defecation	1–6 times/w	0.01 (2)
		Q15*	Need to defecate but ‘false alarm’	6–9 times/d	0.00 (0)
		Q17	Need to strain when defecating	1–6 times/w	0.08 (16)
		Q18*	Difficulty to completely pass stools	every 2^nd/3^rd time	0.04 (9)
		Q20	Abdominal pain	1–6 times/w	0.05 (10)
		Q24	Pain/discomfort in/around the rectal/anal region	1–6 times/w	0.08 (17)
SW	Defecation urgency	Q3	Defecation urgencies prompted toilet visit	≥ 1/w	0.31 (86)
		Q4	Time to defer defecation at defecation urgency	< 10 min	0.39 (108)
	Faecal leakage	Q25*	Faecal odour	≥ 1/w	0.03 (7)
		Q26	Faecal leakage while awake	≥ 1/w	0.06 (16)
		Q28*	Faecal leakage when coughing/laughing/sneezing	≥ 1/w	0.02 (5)
		Q29*	Faecal leakage during physical activity	≥ 1/w	0.02 (6)
		Q30c	Faecal leakage of loose stools	Yes	0.23 (63)
		Q32	Use of protective pads due to faecal leakage	Yes	0.07 (19)
	Mucous	Q18	Mucous in stools	≥ 1/w	0.08 (23)
		Q19	Leakage of mucous while awake	≥ 1/w	0.05 (15)
		Q20*	Leakage of mucous while asleep	≥ 1/w	0.01 (4)
		Q21*	Passed mucous only with bowel movements	≥ 1/w	0.02 (6)
	Pain	Q5	Dull pain in abdomen	≥ 1/w	0.10 (29)
		Q6	Abdominal cramps	≥ 1/w	0.05 (14)
		Q24	Bowel distension due to wind	≥ 1/w	0.19 (53)

*Not studied due to prevalence < 5%.

Table II. All MVA models with mean Az ≥ 0.50 sorted by the highest A_z in each domain, and the dose/volume parameters with frequency > 5% for the models with the best discriminative ability (denoted by *).

Cohort	Symptom domain	Symptom ids	Az (SD) MVAstepwise	Frequency > 5%	Frequency	Az (SD) MVALASSO	Frequency > 5%	Frequency
DK	Defecation urgency	Q23*	0.54 (0.04)	R D55	75%	0.53 (0.04)	R D55	75%
N = 212				R D50	8%		R Dmax	23%
				R Dmax	7%		R D50	8%
		Q22				0.51 (0.03)
	Faecal leakage	Q3Q12Q22*	0.63 (0.02)	AS D100	97%	0.62 (0.02)	AS D100	99%
		Q12Q22	0.59 (0.02)			0.59 (0.02)
		Q3Q12	0.58 (0.03)			0.57 (0.03)
		Q12	0.50 (0.04)			0.50 (0.04)
	Pain	Q17Q20*	0.69 (0.02)	AS V15	82%	0.69 (0.02)	AS V15	82%
				R V40	64%		R V40	68%
				R V35	27%		R V35	28%
		Q17Q20Q24	0.65 (0.02)			0.65 (0.02)
		Q20Q24	0.64 (0.03)			0.65 (0.03)
		Q17	0.64 (0.03)			0.64 (0.03)
		Q17Q24	0.61 (0.03)			0.61 (0.03)
		Q24	0.52 (0.03)			0.52 (0.03)
		Q20				0.51 (0.04)
SW	Defecation urgency	Q4*	0.53 (0.02)	R D40	70%	0.53 (0.02)	R D40	70%
N = 277				AS D95	10%		R V75	21%
				R D45	7%		AS D95	10%
				R V75	6%		R D45	7%
							AS V25	6%
	Faecal leakage 1	Q26Q32*	0.67 (0.02)	AS V30	83%	0.67 (0.02)	AS V30	83%
				AS D95	10%		AS D95	10%
	Faecal leakage 2	Q32*	0.67 (0.03)	AS V30	91%	0.67 (0.03)	AS V30	91%
		Q26	0.62 (0.03)			0.62 (0.03)
		Q30c	0.54 (0.01)			0.54 (0.01)
		Q26Q30c	0.54 (0.01)			0.53 (0.02)
		Q30cQ32	0.52 (0.02)			0.52 (0.02)
		Q26Q30cQ32	0.52 (0.02)			0.52 (0.02)
	Mucous	Q18*				0.54 (0.03)	AS V70	96%
DK+ SW	Defecation urgency	DKQ23	0.62 (0.01)	AS D95	99%	0.62 (0.01)	AS D95	99%
N = 489		SWQ4					R Dmean	27%
	Faecal leakage 1	DKQ3Q12Q22	0.61 (0.01)	AS V30	68%	0.61 (0.01)	AS V30	68%
		SWQ26Q32		R Dmean	63%		R Dmean	63%
				AS D35	15%		AS D35	15%
	Faecal leakage 2	DKQ3Q12Q22	0.57 (0.01)	AS Dmean	26%	0.57 (0.02)	AS Dmean	26%
		SWQ32		AS D35	21%		AS D35	21%
				AS V65	20%		AS V65	20%
				AS MOH35	12%		AS MOH35	12%
				R Dmean	9%		R Dmean	9%
				AS V30	6%		AS V30	6%

Figure 1. Population averaged dose-volume histograms for the highest frequency models of each symptom domain within the two cohorts (error bars denote 95% CI) for patients with < Moderate symptom severity (blue) and with ≥ Moderate symptom severity (red).

Table III. Best-fitting LKB model parameters for each symptom domain in DK, and in SW.

Cohort	Symptom domain	Structure	a (95%CI)	D50 (95%CI) Gy	m (95%CI)	Proportion (N) ≥ Moderate
DK	Defecation urgency	R	100 (40.0–> 100)	83 (80–87)	0.15 (0.11–0.19)	0.17 (37)
N = 212	Faecal leakage	AS	0.02 (0.04–1.00)	81 (62–> 118)	0.69 (0.55–0.89)	0.19 (41)
	Pain	AS	0.09 (0.01–1.00)	86 (69–115)	0.47 (0.39–0.59)	0.09 (20)
		R	100 (8.00–> 100)	148 (124–> 150)	0.41 (0.33–0.51)	0.09 (20)
SW	Defecation urgency	R	3.00 (1.00–6.00)	68 (61–75)	0.53 (0.37–0.89)	0.39 (108)
N = 277	Faecal leakage 1	AS	0.01 (< 0.001–2.00)	87 (75–103)	0.37 (0.31–0.45)	0.09 (24)
	Faecal leakage 2	AS	0.03 (< 0.001–2.00)	86 (75–101)	0.33 (0.27–0.39)	0.07 (19)
	Mucous	AS	0.50 (< 0.001–8.00)	148 (110–> 150)	0.51 (0.43–0.61)	0.08 (23)

Figure 2. Population averaged dose-volume histograms for the highest-frequency models with the best discriminative ability of each symptom domain across the two cohorts (error bars denote 95% CI) for patients with < Moderate symptom severity (blue) and with ≥ Moderate symptom severity (red).