Table 1.

Characteristics of the included studies (n = 21).

Study	Year	Country	Study Design	Study Population		Probiotics (Species, Components)		Probiotics (Daily Administration)		Time of Intervention (Weeks)
				Study Group	Control Group	Study Group	Control Group	Study Group	Control Group
ADULT POPULATION
Chemotherapy treatment
Mego M. et al. [24]	2015	Slovakia	RDBPC 1	23	23	Bifidobacterium breve HA-129 (25%), Bifidobacterium bifidum HA-132 HA (20%), Bifidobacterium longum HA-135 (14.5%), Lactobacillus rhamnosus HA-111 (8%), Lactobacillus acidophilus HA-122 (8%), Lactobacillus casei HA-108 (8%), Lactobacillus plantarum HA-119 (8%), Streptococcus thermophilus HA-110 (6%), Lactobacillus brevis HA-112 (2%), Bifidobacterium infantis HA-116 (0.5%) 10 × 109 CFU 2 per capsule, inulin, maltodextrin, magnesium stearate, ascorbic acid	inulin, maltodextrin, magnesium stearate, ascorbic acid	capsule p.o.3 3 times a day	capsule p.o.	12
Liu J. et al. [36]	2014	China	RCT 4	50	50	Bifidobacterium infantis, Lactobacillus acidophilus, Enterococcus faecalis, Bacillus cereus	no intervention	capsules (4) p.o. 3 times a day	no intervention	4
Radiotherapy treatment
Urbancsek H. et al. [22]	2001	Hungary	RDBPC	102	103	Lactobacillus rhamnosus 1.5 × 10⁹ CFU (1.5 g)	700 mg corn starch, 797 mg microcrystalline cellulose, 1.37 mg iron oxide, 1.13 mg dispersed orange, 1 mg caramel aroma	sachet p.o. 3 times a day	sachet p. o. 3 times a day	up to 1 (depending on the response of the diarrhoea)
Mansouri-Tehrani H.S. et al. [32]	2016	Iran	RCT	22	24	Lactobacillus casei 1.5 × 109 CFU, Lactobacillus acidophilus 1.5 × 1010 CFU, Lactobacillus rhamnosus 3.5 × 109 CFU, Lactobacillus bulgaricus 2.5 × 108 CFU, Bifidobacterium breve 1 × 1010 CFU, Bifidobacterium longum 5 × 108 CFU, Streptococcus thermophilus 1.5 × 108 CFU (500 mg)	corn starch 500 mg	capsule p.o. 2 times a day (second one with yogurt)	capsule p.o. 2 times a day	5
Delia P. et al. [23]	2007	Italy	RDBPC	243	239	Lactobacillus casei, L. plantarum, L. acidophilus, L. delbrueckii subsp. bulgaricus, Bifidobacterium longum, B. breve, B. infantis. Streptococcus salivarius susp. Thermophilus 450 billions/g of viable lyophilized cells	N/A composition of placebo	sachet p.o. 3 times a day	sachet p.o.	from the start of RT 5
Delia P. et al. [29]	2002	Italy	RCT	95	95	Lactobacillus casei, L. plantarum, L. acidophilus, L. delbrueckii subsp. bulgaricus, Bifidobacterium longum, B. breve, B. infantis, Streptococcus salivarius susp. thermophilus	no intervention	bag p.o. 3 times a day	no intervention	N/A
Delia P. et al. [31]	2002	Italy	RCT	95	95	Lactobacillus casei, L. plantarum, L. acidophilus, L. delbrueckii subsp. bulgaricus, Bifidobacterium. longum, B. breve, B. infantis, Streptococcus salivarius susp. Thermophilus 450 billions/g of viable lyophilized	N/A composition of placebo	p.o. 3 times a day	p.o.	from the start of RT to finish cycle of RT
Shao F. et al. [33]	2013	China	RCT	24	22	Bifidobacterium adolescent is 0.5 × 109, Lactobacillus, Streptococcus thermophilus	500 mL Peptiosorb solution (1 cal): 16% protein, 9% fat, 75% carbohydrates/mL)	capsules p.o. 3 times a day	p.o. 1 time a day	2
Radiotherapy and chemotherapy treatment
Giralt J. et al. [18]	2008	Spain	RDBPC	44	41	Lactobacillus casei DN-114 001 108 CFU/g, in addition to the standard starters Streptococcus thermophilus, Lactobacillus delbrueckii, subsp. bulgaricus	sterilised active product with 4 kGy for 5 min	96 mL of fermented liquid yoghurt p.o. 3 times a day	96 mL p.o. 3 times a day	5–6
Ye-Htut-Linn et al. [19]	2017	Myanmar	RDBPC	26	28	Lactobacillus acidophilus LA-5, Bifidobacterium animalis subsp. lactis BB-12 1.75 × 109 lyophilized live	starch	capsule with yogurt p.o. 3 times a day	capsule p.o. 3 times a day	5
Österlund P. et al. [28]	2007	Finland	RCT	98	52	Lactobacillus rhamnosus GG 1–2 × 1010	no intervention	gelatine capsule p.o. 2 times a day	no intervention	24
Sharma A. et al. [20]	2011	India	RDBPC	93	95	Lactobacillus brevis CD2 minimum 2 × 109 viable cells	mixture of sugars and salts	lozenge p.o. 6 times a day	lozenge p. o.	8
Chitapanarux et al. [21]	2010	Thailand	RDBPC	32	31	Lactobacillus acidophilus minimum 109, Bifidobacterium bifidum minimum 109 (250 mg)	magnesium stearate, talc, purified water	capsules (2) p.o. 2 times a day	capsules p. o. 2 times a day	7.3
Topuz E. et al. [34]	2008	Turkey	NRS 6	17	20	250 mL of kefir	0.09% NaCl	oral lavage 2 times a day	oral lavage 2 times a day	N/A
de Sanctis V. et al. [30]	2019	Italy	RCT	32	36	Lactobacillus brevis CD2 2 × 109 viable cells	sodium bicarbonate	lozenge p.o. 6 times a day	mouthwash 3 times a day	from the start of the RT to 1 week after
Jiang C et al. [25]	2018	China	RDBPC	58	35	Bifidobacterium longum, Lactobacillus lactis, Enterococcus faecium	starch	capsules (3) p.o. 2 times a day	capsules (3) p.o. 2 times a day	up to 7
Demers M et al. [26]	2014	Canada	RDBPC	standard dose 91 high dose 64	91	Lactobacillus acidophilus LAC-361, Bifidobacterium longum BB-536 standard dose 1.3 billion CFU high dose 10 billion CFU	N/A	capsule p.o. standard dose 2 times a da high dose 3 times a day	N/A	from the start of RT to the end of RT
Xia C. et al. [27]	2021	China	RDBPC	36	34	Lactobacillus plantarum MH-301 109 CFU, Bifidobacterium animalis subsp. Lactis LPL-RH 109 CFU, Lactobacillus rhamnosus LGG-18 109 CFU, Lactobacillus acidophilus 109 CFU	N/A	capsule p.o. 2 times a day	p.o. 2 times a day	6–7
CHILD POPULATION
Chemotherapy treatment
Reyna-Figueroa J. et al. [38]	2019	Mexico	RCT	30	30	Lactobacillus rhamnosus GG 5 × 109 CFU, maltodextrin	N/A	sachet p.o. 2 times a day	N/A	up to 1 (upon completion of: a 7-day probiotic course/chemotherapy/neutropenia onset)
Wada M. et al. [35]	2009	Japan	RCT	18	22	109 freeze-dried, live Bifidobacterium breve strain Yakult, corn starch, hydroxypropyl cellulose (1 g)	corn starch and hydroxypropyl, cellulose	powder p.o. 3 times a day	powder p.o. 3 times a day	4–20
Radiotherapy treatment
Shu-Xu Du et al. [37]	2018	China	NRS	80	80	Bacillus licheniformis	N/A	capsule p.o. 3 times a day	N/A	from the start of RT to the end of RT

¹ RDBPC—randomized, double-blind, placebo-controlled; ² CFU—colony-forming unit; ³ p.o.—orally; ⁴ RCT—randomized controlled study; ⁵ RT—radiation therapy; ⁶ NRS—non-randomized controlled study.