Braga et al. (2015): Effect of Zinc Supplementation on Serological Response to Vaccination Against Streptococcus Pneumoniae in Patients Undergoing Chemotherapy for Colorectal Cancer

Reference ↗
Title	Effect of Zinc Supplementation on Serological Response to Vaccination Against Streptococcus Pneumoniae in Patients Undergoing Chemotherapy for Colorectal Cancer
Topic	Zinc
Author	Braga, CBM, Santos, IKFM, Palmeira, P, Peria, FM, Ribeiro, SMF, Martinez, EZ, Rocha, JJR, Cunha, SFC
Year	2015
Journal	Nutrition and cancer
DOI	https://dx.doi.org/10.1080/01635581.2015.1053497

Brief summary

This study investigated the effect of a pneumococcal vaccination in patients with colorectal adenocarcinoma who were additionally given either zinc or a placebo. Two methods were used to test the body's response to the vaccination. First, the concentration of antibodies against bacteria or viruses (pathogens) of the pneumococcal disease was measured, and second, the seroconversion rate was examined, which indicates the formation of immunity to the disease. In both arms, an increased antibody concentration in the blood was observed after vaccination, indicating that all patients, regardless of their health status, showed an adequate immunological response to the vaccination. Regarding the seroconversion rate, no differences were found either. The authors conclude from these results that zinc could help maintain an adequate seroconversion rate, but this does not align with the presented data, as the zinc and placebo arms, as previously reported, did not differ. The conclusion, therefore, is that according to the results of this study, zinc appears to have no influence on the body's response after a pneumococcal vaccination. Further criticisms of this investigation include the small number of patients, the unclear randomization method, and the impression of selective reporting.

Diese Studie untersuchte die Wirkung einer Pneumokokken-Impfung bei Patienten mit kolorektalem Adenokarzinom, die zusätzlich dazu entweder Zink oder ein Placebo bekamen. Um die Reaktion des Körpers auf die Impfung zu testeten wurden zwei Methoden angewandt. Zum einen wurde die Konzentration an Antikörpern gegen Bakterien oder Viren (Erreger) der Pneumokokken Erkrankung gemessen und zum anderen die Serokonversionsrate untersucht, die etwas über die Bildung einer Immunität gegenüber der Erkrankung aussagt. In beiden Armen zeigte sich nach der Impfung eine erhöhte Antikörperkonzentration im Blut, was verdeutlicht, dass alle Patienten, unabhängig von ihrem Gesundheitsstatus eine angemessene immunologische Antwort auf die Impfung zeigten. Bezüglich der Serokonversionsrate wurden ebenso keine Unterschiede festgestellt. Die Autoren schließen aus diesen Ergebnissen darauf, dass Zink zur Aufrechterhaltung einer angemessenen Serokonversionsrate verhelfen könne, was sich aber nicht mit den dargelegten Daten deckt, da sich Zink- und Placebo-Arm, wie bereits berichtet, nicht unterschieden. Das Fazit ist daher, dass Zink laut dieser Studienergebnisse scheinbar keinen Einfluss auf die Reaktion des Körpers nach einer Pneumokokken Impfung hat. Weitere Kritikpunkte dieser Untersuchung sind die kleine Anzahl an Patienten, die unklare Randomisierungsmethode und der bestehende Eindruck des selektiven Berichtens.

Study Design

Prospective / Retrospective Prospective: forward-looking, examples include clinical trials, cohort studies, and long-term observational studies;</br>Retrospective: backward-looking, relying on existing data, examples include case-control studies and retrospective cohort studies	Prospective
Monocentric / Multicentric Monocentric: conducted in one center/ hospital; </br>Multicentric: conducted in multiple centers/ hospitals	Monocentric
Blinding No: Open, all parties are aware of group assignments;</br>Single: one party is unaware of group assignments (generally participants);</br>Double: two parties are unaware of group assignments (generally the participants and the researchers); </br>Triple: concealing group assignment from additional parties	Double
Is randomized	Yes
Cross-over Participants alternate between different treatment groups or conditions over a specified period, allowing each participant to serve as their own control	No
Number of arms	2

Study characteristics

Inclusion criteria	Surgery for Stage II, III, or IV colon or rectum/sigmoid colon cancer; indication of chemotherapy
Exclusion criteria	History of autoimmune disease, chronic inflammatory disease, active infectious diseases, liver or kidney disease, use of immunosuppressive drugs, or supplements containing zinc or copper, and chemotherapy or radiotherapy within 12 months before the study
N randomized	25
Analysis PP: Per Protocol analysis, i.e. only participants included who adhered to the study protocol.</br>ITT: Intention-to-treat analysis, i.e. all randomized participants included regardless of any drop-outs or changes in assignment.</br>mITT: modified Intention-to-treat analysis can refer to analyses in which participants with missing outcome data are excluded or it can refer to analyses in which only participants who received at least one treatment dose are included. In this case, participants dropped out of the study prematurely for reasons unrelated to the treatment.	ITT Analysis
Specifications on analyses	The specific analysis method is not stated in the study, however, according to the authors, all included patients were evaluated at the end of the study
Countries of data collection	Brazil
LoE Level of evidence	2b Oxford 2009
Outcome timeline Data collection times	T0: perioperative (prior to vaccination) T1: before the chemotherapy (4th wk of study) T2: after 3 cycles of chemotherapy (16th wk of study)

Characteristics of participants

Setting Refers to cancer therapy setting.</br>- Curative therapy: aims to completely eradicate a disease and achieve a full recovery; </br>- Neo-adjuvant therapy: form of curative therapy, given before the primary treatment for cancer (usually surgery); </br>- Adjuvant therapy: form of curative therapy, given after the primary treatment for cancer (usually surgery); </br>- Palliative therapy: focuses on providing relief from symptoms and improving the quality of life for patients, without necessarily targeting the underlying disease; </br>- Active surveillance: involves close monitoring of disease progression without any intervention (typically used for prostate cancer);</br>- No therapy setting: Patients who completed therapy/are currently not in cancer treatment, cancer survivors.	Curative
Types of cancer "Other Cancers" means that only a subpopulation was specified, but further unspecified cancer types were included	Colorectal Cancer - Colon Cancer, Colorectal Cancer - Rectal Cancer
Cancer stages Early Stage: generally refers to cancer that is localized to the area where it started, mostly stages I and II;</br>Advanced Stage: cancer that has spread beyond its original site, mostly stages III and IV, with stage IV indicating distant metastasis	Early Stage, Advanced Stage
Specifications on cancer stages	Stage II, III, or IV
Comorbidities	NI
Current cancer therapies	Chemotherapy
Specifications on cancer therapies	Chemotherapy regimen: CAPOX (capecitabine + oxaliplatin), Capecitabine or 5-fluorouracil + folinic acid
Previous cancer therapies	NI
Gender	Mixed
Gender specifications	36% male (n=9)
Age groups	Adults (18+)
Age groups specification	MW (SD): 63 (15)

Arms

Arm type Active control: group receives active treatment; </br>Passive control: for example treatment as usual, waiting control, no treatment	Intervention
Number of participants (arm) N randomized	10
Drop-out Number of participants who left the study for any reason or did not provide information on every data collection date	NI
Drop-out reasons	NI
Intervention	Zinc sulfate
Dosage and regime	2 zinc sulfate capsules/ day (each containing 35 mg of elemental zinc); first capsule 1h after breakfast and the other 1h after dinner + vaccination with 1 dose of 0.5 mL of 23-valent pneumococcal polysaccharide vaccine (Pneumovax 23 , Merck, Whitehouse Station, NJ), containing 25 mg of capsular polysaccharide antigen from 23 different pneumococcal serotypes (1, 2, 3, 4, 5, 6B, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B, 17F, 18C, 19A, 19F, 20, 22F, 23F, and 33F); 2 days after zinc supplementation started
One-time application	No
Duration in days For long-term interventions, the number of days is an estimation.</br>A value of -999 indicates that the exact duration cannot be extracted from the study due to ambiguous or incomplete information. See Outcome timeline or Dosage and regime for further information.	112
Side effects / Interactions	NI

Arm type Active control: group receives active treatment; </br>Passive control: for example treatment as usual, waiting control, no treatment	Placebo
Number of participants (arm) N randomized	15
Drop-out Number of participants who left the study for any reason or did not provide information on every data collection date	NI
Drop-out reasons	NI
Intervention	Placebo
Dosage and regime	2 placebo capsules/ day (composed of wheat starch with no added zinc) + vaccination with 1 dose of 0.5 mL of 23-valent pneumococcal polysaccharide vaccine (Pneumovax 23 , Merck, Whitehouse Station, NJ), containing 25 mg of capsular polysaccharide antigen from 23 different pneumococcal serotypes (1, 2, 3, 4, 5, 6B, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B, 17F, 18C, 19A, 19F, 20, 22F, 23F, and 33F); 2 days after zinc supplementation started
One-time application	No
Duration in days For long-term interventions, the number of days is an estimation.</br>A value of -999 indicates that the exact duration cannot be extracted from the study due to ambiguous or incomplete information. See Outcome timeline or Dosage and regime for further information.	112
Side effects / Interactions	?

Outcomes

Antibodies

Outcome type As specificed by the authors	NI
Outcome specification	Concentrations of antibodies against polysaccharides PS1, PS5, PS6, PS9, PS14, and PS18
Type of measurement	ELISA protocol (Enzyme-Linked Immunoabsorbent Assay)
Results during intervention - Results during intervention means that the time of data collection is during or shortly after the period of the intervention (e.g. on the last day or a few days after). The results therefore still relate to the direct effects of the intervention.</br>- Results after intervention means there is a longer break between the time of data collection and the end of the intervention, e.g. more than a week. The results relate more to long-term effects.</br>- If a categorization in Results during vs. after intervention is not possible (e.g. survival data), the results are summarized under Results after intervention under the headline "Overall".	Significantly higher prevaccinal concentrations of antibodies against polysaccharides PS1, PS5, PS6, PS9, PS14, and PS18 in both arms at both 4 and 16 week after vaccination; concentrations of PS6-specific antibodies in the end of study significantly higher in the placebo arm (MW (95% CI): 2.96 (1.74–5.03), p < 0.01)
Results after intervention - Results during intervention means that the time of data collection is during or shortly after the period of the intervention (e.g. on the last day or a few days after). The results therefore still relate to the direct effects of the intervention.</br>- Results after intervention means there is a longer break between the time of data collection and the end of the intervention, e.g. more than a week. The results relate more to long-term effects.</br>- If a categorization in Results during vs. after intervention is not possible (e.g. survival data), the results are summarized under Results after intervention under the headline "Overall".	NI

Risk of Bias Assessment: Cochrane RoB tool 2.0
Bias arising from the randomization process	?
Bias due to deviation from intended intervention (assignment to intervention)	?
Bias due to deviation from intended intervention (adhering to intervention)	NA
Bias due to missing outcome data	?
Bias in measurement of the outcome	?
Bias in selection of the reported result	?
Other sources of bias	?
Overall RoB judgment	?

Seroconversion

Outcome type As specificed by the authors	NI
Outcome specification	NA
Type of measurement	Blood Test
Results during intervention - Results during intervention means that the time of data collection is during or shortly after the period of the intervention (e.g. on the last day or a few days after). The results therefore still relate to the direct effects of the intervention.</br>- Results after intervention means there is a longer break between the time of data collection and the end of the intervention, e.g. more than a week. The results relate more to long-term effects.</br>- If a categorization in Results during vs. after intervention is not possible (e.g. survival data), the results are summarized under Results after intervention under the headline "Overall".	No significant difference in the rate of seroconversion against vaccine antigens according to selected antigens (PS1, PS5, PS6, PS9, PS14, PS18)
Results after intervention - Results during intervention means that the time of data collection is during or shortly after the period of the intervention (e.g. on the last day or a few days after). The results therefore still relate to the direct effects of the intervention.</br>- Results after intervention means there is a longer break between the time of data collection and the end of the intervention, e.g. more than a week. The results relate more to long-term effects.</br>- If a categorization in Results during vs. after intervention is not possible (e.g. survival data), the results are summarized under Results after intervention under the headline "Overall".	NI

Risk of Bias Assessment: Cochrane RoB tool 2.0
Bias arising from the randomization process	?
Bias due to deviation from intended intervention (assignment to intervention)	?
Bias due to deviation from intended intervention (adhering to intervention)	NA
Bias due to missing outcome data	?
Bias in measurement of the outcome	?
Bias in selection of the reported result	?
Other sources of bias	?
Overall RoB judgment	?

Zinc level

Outcome type As specificed by the authors	NI
Outcome specification	NA
Type of measurement	Spectrophotometry
Results during intervention - Results during intervention means that the time of data collection is during or shortly after the period of the intervention (e.g. on the last day or a few days after). The results therefore still relate to the direct effects of the intervention.</br>- Results after intervention means there is a longer break between the time of data collection and the end of the intervention, e.g. more than a week. The results relate more to long-term effects.</br>- If a categorization in Results during vs. after intervention is not possible (e.g. survival data), the results are summarized under Results after intervention under the headline "Overall".	Zinc supplementation increased the zinc plasma concentrations
Results after intervention - Results during intervention means that the time of data collection is during or shortly after the period of the intervention (e.g. on the last day or a few days after). The results therefore still relate to the direct effects of the intervention.</br>- Results after intervention means there is a longer break between the time of data collection and the end of the intervention, e.g. more than a week. The results relate more to long-term effects.</br>- If a categorization in Results during vs. after intervention is not possible (e.g. survival data), the results are summarized under Results after intervention under the headline "Overall".	NI

Risk of Bias Assessment: Cochrane RoB tool 2.0
Bias arising from the randomization process	?
Bias due to deviation from intended intervention (assignment to intervention)	?
Bias due to deviation from intended intervention (adhering to intervention)	NA
Bias due to missing outcome data	?
Bias in measurement of the outcome	?
Bias in selection of the reported result	?
Other sources of bias	?
Overall RoB judgment	?

Funding and Conflicts of Interest

Funding	Fundacao de Amparo à Pesquisa do Estado de Sao Paulo (FAPESP), Brazil (Grant # 2010/05152-1 and 2010/08787-1)
Conflicts of Interest	NI

Further points for assessing the study

Sample

Power analysis performed	?
- Sample size corresponds to power analysis	NI
- Reasons for insufficient sample size based on power analysis	NI
If no power analysis performed: at least moderate sample size (n >= 30 per arm)	NI
Ethnicity mentioned	NI

Alternative Explanation

Other explanations for an effect besides the investigated intervention	NI
- Possibility of attention effects	?
- Possibility of placebo effects	?
- Other reasons	?

Statistics

Correct use of parametric and non-parametric tests Testing for normal distribution only necessary if parametric tests are used, NI: use of parametric tests without report of normal distribution testing	NI
Correction for multiple testing	?
Measurement of compliance	?
Consistent reporting in numbers (figures, flowchart, abstract, results)	?
Comprehensive and coherent reporting	?
Cross-over	NI
- Sufficient washout period	?
- Tested for carry-over effects	?
- Tested for sequence effects	?

Interpretation of results

Effect sizes reported (clinical vs. statistical significance)	?
Side effects systematically recorded	?
Side effects considered in result interpretation	?
Ethics votum	?

Additional Notes

PRO:

• Ethics vote available
• Double blinding

CONTRA:

• The comparisons of the groups (i.e. within the cancer patients or the comparison with the healthy healthy controls) is very selective and difficult to understand - also leads to selective and erratic reporting
• Unclear type of randomization, arm A consists of 10 and arm B of 15 patients
• Small sample without testing of normal distribution as a prerequisite for t-test
• No examination of the adverse events