Table 1.

Characteristics of included studies.

Reference	Type of Cancer and Sample Size	Patients’ Characteristics	Intervention	Intervention Time Point/ Duration	Primary Outcome(s)
Akita et al. (2019) [45]	PaCa n = 62	IG (n = 31): ♂11; ♀20 67.8 (±10.7) years 22.3 (±2.39) kg/m² CG (n = 31): ♂16; ♀15 66.4 (±9.8) years 22.0 (±3.06) kg/m²	IG: normal diet + EPA-enriched EN as food supplement and 3 nutritional consultations (before, during and after radiation). Composition (target): 2 bottles (440 mL): 560 kcal + EPA (Prosure® (Abbott, Japan))/d. CG: Normal diet.	During neoadjuvant chemoradiotherapy (approx. 5 weeks)	Ratio of skeletal muscle mass
Ashida et al. (2019) [46]	Periampullary cancer n = 20	IG: (n = 11): ♂5; ♀6 64 (±11) years 55.9 (±13.5) kg 22.3 (±7.6) kg/m² CG: (n = 9): ♂6; ♀3 69 (±6) years 56.3 (±7.2) kg 21.4 (±2.5) kg/m²	IG: dietary supplement (target: 600 kcal/d) with EPA fortified diet (2.0 g/d) + regular diet (1200 kcal). CG: standard diet: isocaloric, isonitrogenous standard diet (target: 600 kcal/d) without EPA + regular diet (1200 kcal).	7 days preOP	Serum concentration of IL-6
Bauer et al. (2005) [47]	PaCa n = 185	IG: (n = 87): ♂n.a.; ♀n.a. 66.8 (±1.0) years 62.9 (±1.2) kg 22.4 (±0.4) kg/m² CG: (n = 98): ♂n.a.; ♀n.a. 68.3 (±1.1) years 59.3 (±1.3) kg 21.2 (±0.4) kg/m²	IG: target 2 doses of a dietary supplement high in protein and energy + omega-3 fatty acids (1.2 g EPA). CG: isocaloric, isonitrogenous control supplement without omega-3 fatty acids. Both formulas: 310 kcal, 16 g protein. Daily intake Ø 1.5 doses of oral suppl./d (--> 465 kcal and 24 g protein).	Unresectable PaCa; 4–8 weeks	Body composition (body weight, lean body mass)
Bourdel-Marchasson et al. (2014) [48]	Mixed n = 336 thereof PaCa n = 62	IG: (n = 169): ♂81; ♀88 77.7 (±5.2) years WL: 8.9 (±6.6)% CG: (n = 167): ♂91; ♀76 78.3 (±4.7) years WL: 8.6 (±7.9)%	IG: usual care + NI: usual nutrient supply + nutritional counselling. Energy target: 30 kcal/kg body weight/d. Protein target: 1.2 g/kg body weight/d. Possibly (if necessary) dietary supplement. CG: usual care group: normal nutrient supply everything allowed.	According to duration of chemotherapy; 3–4 months	1-year mortality
Braga et al. (1999) [49]	CoCa, GaCa, PaCa n = 171 thereof PaCa n = 22	IG: (n = 85): ♂50; ♀35 60.9 (±11.9) years 65.8 (±10.9) kg CG: (n = 86): ♂56; ♀30 60.8 (±9.7) years 67.6 (±11.2) kg	IG: EN (Impact, Novartis) (1 L/d) (target): 12.5 g arginine, 1.2 g RNA, 3.3 g omega-3 fatty acids. CG: similar EN without enrichments Both: isocaloric and isonitrogenic.	6 h postOP–7 days postOP	Rate of postoperative infectious complications and LOS
Braga et al. (2012) [50]	PaCa, periampullary cancer n = 36 thereof PaCa n not reported	IG: (n = 18): ♂11; ♀7 64.1 (±10.8) years 25.9 (±4.4) kg/m² WL: 4.4% CG: (n = 18): ♂12; ♀6 64.1 (±12.6) years 24.2 (±3.8) kg/m² WL: 4.3%	IG: dietary supplement as pre-conditioned oral carbohydrate supplement (pONS) enriched with glutamine, antioxidants and green tea extract. Target: 3 doses (first 1 day before surgery at 3 pm, second 6 h later, third on the day of surgery 3 h before induction of anaesthesia); pONS was administered shortly before surgery to have glutamine and antioxidants ready for surgery. CG: Placebo drink.	1 day preOP–3 h preOP	Postoperative host’s antioxidant capacity (TEAC) and inflammatory response (CRP)
Brennan et al. (1994) [51]	PaCa, periampullary cancer n = 117 thereof PaCa n not reported	IG: (n = 60): ♂34; ♀26 65 (34–86) years WL: 5.8 (0–18)% CG (n = 57): ♂27; ♀29 63 (30–86) years WL: 6.8 (0–22)%	IG: total PN 1 day postOP until day with oral intake >1000 kcal/d (12.3 (6–34) d). Total PN (target): 1 g/kg BW/d protein and 30–35 kcal/kg/d + electrolytes, vitamins, minerals (non-protein energy from 70% glucose, 30% fat). CG: dextrose-containing saline until postoperative intake exceeds 1000 kcal/d (22.2 (3–69) d).	1 day postOP until oral intake >1000 kcal/d	Generic role of total PN (postOP mortality and morbidity)
Daly et al. (1995) [52]	OeCa, GaCa, PaCa, others n = 60 thereof PaCa n = 15	IG1 and 2: (n = 30): ♂25; ♀5 61 (±12) years WL: n = 12 CG 1 and 2:(n = 30): ♂16; ♀14 61 (±10) years WL: n = 10	IG1 (n = 18): enteral IN in hospital and ambulant. IG 2: (n = 12): enteral IN only in hospital. CG 1: (n = 19): EN with standard diet in hospital and ambulant. CG 2: (n = 11): enteral standard diet only in hospital. Patients did not receive oral nutrition for the first 7 days postOP.	1 day postOP –12–16 weeks after diagnosis	Clinical outcome, white blood cell fatty acid composition and PGE2 secretion
Douglass et al. (1978) [53]	PaCa, GaCa, CoCa n = 30 thereof PaCa n = 15	No characteristics: n = 13 PaCa; n = 2 Ampullary or Duodenal Ca; n = 5 GaCa n = 5 Rectosigmoidal Ca; n = 4 RectalCa; n = 1 AnalCa	IG: standard diet + dietary supplement (3 times/d) (300 mL of chilled flavoured solution (1 kcal/mL)/ d: 900 kcal. CG: standard diet.	Before planned radiotherapy; between meals three times/d	Weight loss and weight changes
Fearon et al. (2003) [54]	PaCa n = 200	IG: (n = 95): ♂54; ♀41 67 (±1) years 60.3 (±1.1) kg 21.8 (±0.4) kg/m² WL: 17.9 (±0.9)% CG: (n = 105): ♂56; ♀49 68 (±1) years 61.4 (±1.2) kg 22.0 (±0.4) kg/m² WL: 17.1 (±0.8)%	IG: target of 2 doses of dietary supplement with 310 kcal each, 16 g protein, 6 g fat with 1.1 g EPA and antioxidants. CG: target of 2 doses of dietary supplement with 310 kcal each, 16 g protein, 6 g fat and antioxidants.	Advanced PaCa (unresectable) with weight loss; 8 weeks	Body weight and body composition
Gade et al. (2016) [55]	PaCa n = 35	IG: (n = 19): ♂7; ♀12 68 (50–81) years 70.5 (50.8–103.4) kg 24.3 (18.8–28.3) kg/m² WL total: −5.5% (−16.5–2.1) WL last Month: 1.9% (−9.4–2.1) CG: (n = 16): ♂10; ♀6 69 (53–79) years 70.5 (47.5–95.9) kg 23.8 (18.1–30.8) kg/m² WL total: −7.9% (−33.0–3.1) WL last month: 3.95% (−12.9–3.1)	IG: oral EN as IN with target of 1.5 g protein/kg (per pack 16.8 g protein + 250 mL water) between meals (target). Consumption amounts should be recorded in diaries. Recording of other protein intake one week before via Questionnaire on consumption frequency. Estimated dosage (1–4 packs/d) (250–1000 mL: 16.8–67.2 g protein/d) (median intake at 2 pck./d). CG: standard of clinical care (screening with NRS-2002; individual counselling by nursing staff on the topic of food supplements and visit of a nutritionist before diagnosis).	7 days preOP	Overall postoperative complications and LOS
Gavazzi et al. (2016) [56]	OeCa, GaCa, PaCa, bile duct cancer n = 79 thereof PaCa n = 13	IG: (n = 38): ♂23; ♀15 67 (62–74) years CG: (n = 41): ♂26; ♀15 69 (58–76) years	IG: HEN according to energy requirements by Harris and Benedict. Overnight supplementation to oral diet with any polymeric standard diet containing 1–1.5 kcal/mL, 50–60% carb, 25–35% lipids, 12–20% proteins (target). HEN could be discontinued 2 months after surgery if 5% weight gain was recorded. CG: nutritional counselling by a dietician incl. total energy and protein requirements. If necessary, prescription of oral food supplements.	During oncologic treatment; 1 day postOP– regular oral intake.	Nutritional status (body weight, weight change)
Giger et al. (2007) [57]	GaCa, PaCa, periampullary cancer n = 46 thereof PaCa n = 30	IG1 (n = 14): ♂8; ♀6 64.4 (30–84) years 23.7 (±3.5) kg/m² IG 2 (n = 17): ♂10; ♀7 57.1 (33–77) years 23.3 (±4.0) kg/m² CG (n = 15): ♂9; ♀6 63.0 (47–79) years 22.7 (±3.3) kg/m²	IG1: enteral IN (Impact® (Novartis Consumer Health, Switzerland)) 5 days (1 L/d). IG 2: enteral IN + dietary supplement glycine (Impact plus glycine® (Novartis Consumer Health, Switzerland)) 2 days. CG: no preoperative nutritional support. IG 1 and IG 2: received enteral IN for 7 days postOP, diet should provide 25 kcal/kg/d (target).	5–2 days preOP IN 1–7 days postOP suppl. or EN + suppl.	Postoperative serum level of C-reactive protein
Hamza et al. (2015) [58]	Periampullary cancer n = 37	IG: (n = 17): ♂9; ♀8 63 (58–69) years WL: 9.2 (6.8–11.6)% CG: (n = 20): ♂11; ♀9 67 (63–70) years WL: 9.6 (7.5–11.8)%	IG: EN: immune-boosting nutrition: Impact® (oral) (Novartis Medical Nutrition, UK) with arginine, omega-3 fatty acids, mRNA. Both: provide 150 kcal/100 mL, non-isonitrogenous. Protein content Impact: 8.4 g/100 mL vs. 6.0 g/100 mL in standard diet due to addition of arginine and mRNA in Impact diet. CG: preOP EN with Fresubin® (Fresenius Kabi Ltd., UK).	14 days preOP; 24 h to min. 7 days postOP	Parameters of systematic immune function (IL-1-α, TNF-α, total lymphocyte count (TLC), CD4, CD8, CD25, CD56, CH50, C3, C4)
Hyltander et al. (2005) [59]	OeCa, GaCa, PaCa, others n = 80 thereof PaCa n not reported	IG1 (n = 26): ♂18; ♀8 62 (±2) years 23.6 (±0.6) kg/m² WL: 5 (±0.4)% IG 2 (n = 27): ♂17; ♀10 62 (±2) years 23.8 (±0.6) kg/m² WL: 5 (±0.3)% CG (n = 27): ♂19; ♀9 63 (±2) years 23.8 (±0.5) kg/m² WL: 5 (±0.8)%	IG1: EN + oral nutrition. IG 2: PN + oral nutrition. CG: oral nutrition. Composition of EN + PN(%kcal): 35 (±3)% fat; 39 (±4)% carb; 16 (±2)% protein; protein 0.9–1.1 g/kg BW/d. Pre- and postOP: counselling by dietician with implementation advice on energy intake, frequency of meals, liquid and solid foods. Oral nutritional supplements were offered (high energy and high protein were recommended). IG 1: Impact® (Novartis Nutrition) (1–10 days postOP). From 11 days postOP standard enteral formula with 1000 mL/d (Nutridrip standard® (Novartis Nutrition)). IG 2: Vitrimix® (Fresenius Kabi) (900 kcal) incl. vitamins, minerals and trace elements CG: standard electrolyte solution. All patients in all groups received recommendations from nutritionists.	1–10 days postOP–EN; then EN with standard formula. Pre- and post-discharge: nutritional counselling	Recovery of nutritional state (body fat, lean body mass)
Jo et al. (2006) [60]	Periampullary cancer n = 60	IG (n= 32): ♂19; ♀13 56.8 (±9.4) years WL: 3.2 (0–20.5)% CG (n = 28): ♂10; ♀18 56.9 (±10.3) years WL: 5.9 (0–13.4)%	IG: PN as amino acid suppl. + glutamine (2.0 g/100 mL; 15% amino acid solution; target: 10 mL = 0.2 g glutamine/kg BW/d). CG: PN isonitrogenous (target: 1.3 g/kg BW amino acids/d); postOP supplemental (30 kcal/kg/d with 1.3 g/kg amino acids).	Day 2 preOP–5 days postOP	Patient’s discharge from hospital
Klek et al. (2008) [61]	GaCa, PaCa, n = 183 thereof PaCa n = 69	IG: (n = 92): ♂34; ♀14 62.3 (±11.3) years BMI <19 kg/m²: n = 17 BMI >19 kg/m²: n = 74 WL <10% (last 3–6 month): n = 73 WL >10% (last 3–6 month): n = 16 CG: (n = 91): ♂35; ♀13 62.1 (±10.9) years BMI <19 kg/m²: n = 10 BMI >19 kg/m²: n = 38 WL <10% (last 3–6 month): n = 76 WL >10% (last 3–6 month): n = 18	IG: enteral IN: Reconvan® (Fresenius Kabi, Poland). CG: EN standard oligopeptide diet Peptisorb® (Nutricia Ltd., Poland). Energy same; protein target (CG: 4.0 g vs. IG 5.5 g); total fat target (CG: 1.7 g vs. IG: 4.1 g) (SAFA: 1.0 vs. 3.3; of which MCT: 0.8 vs. 1.9); Sodium: 100 mg vs. 138; Potassium: 150 mg vs. 207. CG: standard oligopeptic EN.	6 h postOP–7 days postOP	Postoperative infectious complications
Klek et al. (2011) [62]	PaCa, GaCa, n = 305 thereof PaCa n = 94	IG: (n = 152): ♂92; ♀60 60.2 (±12.4) years 17.9 (±2.8) kg/m² WL: 18.3 (±4.4)% CG: (n = 153): ♂89; ♀62 [sic] 61.5 (±11.8) years 17.9 (±2.8) kg/m² WL: 18.8 (±4.9)%	6 h after surgery with 5% glucose solution for the first 12 h, following. IG: postOP enteral IN: Reconvan®” (Fresenius Kabi, Poland). CG: standard oligopeptide diet: infusion of Peptisorb® (Nutricia Ltd. Poland).	6 h postOP until 7 days postOP	Number of complications
Krueger et al. 2016 [63]	Biliopancreatic lesions partly as PaCa n = 100	IG: (n = 51): ♂28; ♀23 69.5 (58.2–75.8) years 80.6 (69.8–87.8) kg 26.6 (24.3–32.0) kg/m² WL b. d.: 3.0 (12.0–0.0) kg CG: (n = 49): ♂29; ♀20 61.5 (55.6–71.3) years 75.6 (65.0–85.0) kg 25.3 (22.4–27.8) kg/m² WL b. d.: 5.0 (8.2–0.0) kg	IG: 1000 mL PN (target: 700 kcal, 25.3 g protein, 30 g fat, 75 g glucose + adapted nutrition with vitamins, trace elements on fasting days). CG: 1000 mL isotonic electrolyte solution on fasting days. Same daily oral energy intake during non-fasting days in hospital in CG and IG (1049 vs. 1082 kcal). Median suppl. PN (IG): 1400 kcal.	Undergoing in-hospital work-up for biliopancreatic mass lesions on fasting days	Body weight/ weight gain
Lobo et al. (2006) [64]	OeCa, GaCa, PaCa, n = 108 thereof PaCa n = 15	IG: (n = 54): ♂40; ♀14 65.7 (±1.4) years BMI <19 kg/m²: n = 4 BMI >19 kg/m²: n = 50 CG: (n = 54): ♂43; ♀11 66.6 (±1.4) years BMI <19 kg/m²: n = 5 BMI >19 kg/m²: n = 49	IG: experimental enteral IN. CG: isonitrogenous, isocaloric standard EN.	4 h postOP–10–15 days postOP	Development of infectious complications
Mori et al. (2019) [65]	PaCa n = 39	IG: (n = 19): ♂11; ♀8 66 (41–83) years 20.4 (15.0–26.2) kg/m² CG: (n = 20): ♂12; ♀8 64 (41–83) years 20.2 (17.7–29.9) kg/m²	Fat-free elemental EN (via jejunostomy tube). IG: EN until 3 months postOP (91 days (87–93)). CG: until adequate oral intake was achieved (10 days (8–45)). Composition: EN with target 600 kcal/d (2 doses in total) Elental® (EA Pharma Co., Ltd., Japan) with 4.4 g protein/ 100 Kcal.	1 day postOP–3 months postOP	Complications necessitating readmission (postOP)
Moses et al. (2004) [66]	PaCa n = 24	IG: (n = 9): ♂6; ♀3 65 (±2) years 21 (±1) kg/m² WL: 21 (±2)% CG: (n = 15): ♂4; ♀11 70 (±3) years 20 (±1) kg/m² WL: 19 (±2)%	IGandCG: dietary supplement 8 weeks: 2 doses of 237 mL each containing 16 g protein, 311 kcal (target), both oral supplements ready-to-use, high calorie, high protein, low fat formulas which were isocaloric and isonitrogenic. IG: with omega-3 fatty acids (1.1 g EPA). CG: without omega-3 fatty acids; omega-3 fatty acids: balanced by omega-9 fatty acids.	Home-living PaCa patients (unresectable); 8 weeks	Body weight/ body composition
Park et al. (2012) [67]	PaCa, periampullary cancer n = 38 thereof PaCa n = 14	IG (n = 18): ♂7; ♀11 62.7 (±10.3) years 63.6 (±9.2) kg 23.8 (±3.9) kg/m² WL: 3.1 (±3.6) kg CG (n = 20): ♂12; ♀8 61.3 (±13.2) years 62.7 (±8.5) kg 23.5 (±2.1) kg/m² WL: 1.9 (±1.4) kg	IG: EN: target of 25 kcal/kg (18 h/d). CG: total PN: target of 25 kcal/kg/d. Solution ratio: glucose to lipids 2:1; non-protein to nitrogen (kcal/kg): 100:1. Total PN with vitamins, electrolytes, trace elements, insulin. 4 and 5 days postOP a sip of water. Within 7 days intake of a regular diet.	IG: 24 h postOP-oral intake >800 kcal/d CG: 1 day postOP-oral intake >800 kcal/ d	Change in weight
Perinel et al. (2016) [68]	PaCa n = 204	IG(PN) (n = 101): ♂40; ♀61 64.02 (±9.90) years 23.76 (±3.44) kg/m² WL: 7.31 (±6.81)% CG (EN) (n = 103): ♂39; ♀64 65.46 (±11.25) years 24.99 (±4.17) kg/m² WL: 6.15 (±6.81)%	PreOP IN for all malnourished patients. IG: PN. CG: EN: isonitrogenous, isocaloric feeding (nasojejunale tube) at 25 mL/h from 1 day postOP. Amount increased by 25 mL/h every 24 h (administration over 20 h). IG and CG target: 30 kcal/kg/d with 1.5 g amino acids/kg/d. Carb-/amino acid-ratio: 3/2.	1 day postOP-oral food intake 60% of nutrient requirement	Incidence of postoperative complications
Slotwinski et al. (2008) [69]	PaCa n = 41	IG: (n = 19): ♂14; ♀5 59.8 (±6.0) years BMI preOP: 23.4 (±4.5) kg/m² BMI postOP: 22.4 (±6.3) kg/m² WL preOP: 6.5 (±2.1)% WL postOP: 9.1 (±2.8)% CG: (n = 22): ♂15; ♀7 54.2 (±4.1) years BMI preOP: 22.2 (±3.2) kg/m² BMI postOP: 21.8 (±3.0) kg/m² WL preOP: 6.3 (±3.4)% WL postOP: 9.2 (±3.2)%	IG: enteral IN: target: 14.7(±2.2)g nitrogen, 177(±26 g) glucose, 51.4(±7.5)g fat, 16.4(±2.4)g glutamine, 10.9(±1.6)g arginine (incl. 91.8(±13.5)g protein and 1529(±224) kcal). CG: standard EN: target: 10.8(±1.3) g nitrogen, 208(±24) g glucose, 66.0(±7.7) g fat (incl. 102(±12) g protein and 1693(±198) kcal). IG+CG: antibiotic as well as low-particle heparin, crystalline-line fluids intravenous and electrolytes as needed.	1–12.3 (±2.0) day postOP	Cellular immunity
Werner at al. (2017) [70]	PaCa n = 33	IG: (n = 18): ♂7; ♀11 70.3 (±8.24) years 21.3 (±1.73) kg/m² CG: (n = 15): ♂9; ♀6 71.3 (±7.51) years 23.7 (±4.10) kg/m²	IG: dietary supplement IN: FO capsule: 60% FO, 40% MCT (6.9 g/100 g EPA and 13.6 g/100 g DHA); target: 3 × 1 capsule. CG: dietary supplement IN: MPL capsule: 35% omega-3 fatty acids phospholipids (mainly phospatidylcholine) + 65% neutral lipids (8.5 g/100 g EPA and 12.3 g/100 g DHA); target: 3 × 1 capsule MPL and FO each 300 mg EPA and DHA/d.	During chemo-/radio-/supportive or alternative therapy (palliative and curative); 6 weeks	Change in weight and appetite

BMI: body mass index; BW: body weight; CG: control group; CoCa: colon cancer; DHA: docosahexaenoic acid; EN: enteral nutrition; EPA: eicosapentaenoic acid; FO: fish oil; GaCa: gastric cancer; HEN: home-enteral nutrition; IG: intervention group; IN: immunonutrition; LOS: length of stay in hospital; MCT: medium-chain triglyceride; MPL: marine phospholipids; n.a.: data not available; NI: nutritional intervention; OeCa: oesophagus cancer; PaCa: pancreatic cancer; PN: parenteral nutrition; RNA: ribonucleic acid; SAFA: saturated fatty acid; WL: weight loss.