Stendell-Hollis et al. (2010): Green tea improves metabolic biomarkers, not weight or body composition: a pilot study in overweight breast cancer survivors

Reference ↗
Title	Green tea improves metabolic biomarkers, not weight or body composition: a pilot study in overweight breast cancer survivors
Topic	Green tea (EGCG)
Author	Stendell-Hollis, NR, Thomson, CA, Thompson, PA, Bea, JW, Cussler, EC, Hakim, IA
Year	2010
Journal	Journal of human nutrition and dietetics: the official journal of the British Dietetic Association
DOI	https://doi.org/10.1111/j.1365-277X.2010.01078.x

Brief summary

In this study, 54 overweight patients who had survived breast cancer were divided into one of two arms. One arm drank 960ml of caffeine-free green tea (including 128.84mg EGCG) daily for 6 months and the control arm drank herbal tea. Neither the participants nor the study leaders knew which arm they belonged to. Both before the start of the study and after the 6 months, weight, BMI and body fat percentage were analysed and compared with each other in addition to various laboratory parameters. There were no significant differences in weight, BMI and body fat percentage between the two arms. On the positive side, the overall good reporting and the monitoring of treatment compliance by means of a tea protocol and the return of used and unused tea bags should be noted. However, the small sample size and the relatively high number of participants who did not complete the study are disadvantageous.

In dieser Studie wurden 54 übergewichtige Patientinnen mit einer überlebten Brustkrebserkrankung in einen von zwei Armen eingeteilt. Die eine Gruppe trank täglich 960ml koffeinfreien Grünen Tee (inkl. 128.84mg EGCG) für 6 Monate und die Kontrollgruppe trank Kräutertee. Weder die Teilnehmer noch die Studienleiter wussten, zu welchem Arm sie gehören. Sowohl vor Beginn der Studie als auch nach den 6 Monaten wurde neben verschiedenen Laborparametern auch das Gewicht, der BMI und der Körperfettanteil untersucht und miteinander verglichen. Dabei zeigten sich keine signifikanten Unterschiede hinsichtlich Gewicht, BMI und Körperfettanteil zwischen beiden Armen. Positiv anzumerken ist die insgesamt gute Berichterstattung und die Kontrolle der Therapieeinhaltung mittels Teeprotokoll und Rückgabe der benutzten und unbenutzten Teebeutel. Nachteilig sind allerdings die kleine Stichprobengröße und die relativ hohe Anzahl an Teilnehmern, die die Studie nicht beendet haben.

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	Multicentric
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	Women aged 18–80 years at the time of study enrolment; body mass index (BMI) in the range 25–40 kg m-2; received chemotherapy (neo-adjuvant or adjuvant with any medically-prescribed gent/regime) for treatment of invasive breast cancer; reported no current use of tobacco (past 12 months); no chronic illness such as diabetes, cardiovascular disease (or to be taking medications to control blood glucose and/or blood lipids) or cancer other than the previously treated breast cancer; willing to refrain from all weight loss diets and supplements for a study period of 6 month
Exclusion criteria	NI
N randomized	54
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.	PP Analysis
Specifications on analyses	Measures of central tendency were computed and frequencies and distributions produced for demographic and clinical characteristics of the study participants and checked for missing values, normalcy and outliers, where appropriate, using the Shapiro–Wilk statistic for the normality test and pearson’s chi-square test for skewness and kurtosis.
Countries of data collection	United States
LoE Level of evidence	2b Oxford 2009
Outcome timeline Data collection times	T0: Baseline T1: after 6 month

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.	No therapy setting
Types of cancer "Other Cancers" means that only a subpopulation was specified, but further unspecified cancer types were included	Breast 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
Specifications on cancer stages	Breast cancer (stage I-III) survivors
Comorbidities	Overweight: participants had a mean weight of 80.2 kg; body mass index (BMI) 30.1 kg m-2; and body fat 46.4%.
Current cancer therapies	No therapy
Specifications on cancer therapies	Breast cancer survivors; completed primary treatment(s) for invasive, early stage breast cancer at least 12 months prior and no more than 10 years prior; received chemotherapy (neo-adjuvant or adjuvant with any medically-prescribed agent/regime) for treatment
Previous cancer therapies	Chemotherapy, Radiation therapy
Gender	Female
Gender specifications	100% female
Age groups	Adults (18+)
Age groups specification	Age in years (SD) per arm green tea arm: 56.6 (8.1) placebo arm: 57.8 (8.5)

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	29
Drop-out Number of participants who left the study for any reason or did not provide information on every data collection date	6
Drop-out reasons	Not arm specified lost to follow-up: no reasons for study discontinuation (n=4); intolerance or dislike of tea product (n=4); difficulty adhering to study protocol as a result of busy schedules (n=3)
Intervention	Green tea
Dosage and regime	Decaffeinated green tea product provided by Unilever, Lipton; 960ml daily (=4 tea bags, inclusive 128.84mg EGCG); tea bags were placed in the provided tea mug and 240 mL of boiling water was added and allowed to steep for a period of 3 minutes + all participants: required to successfully complete a 2 week run-in period consisting of daily intake of 960 mL of herbal tea
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.	180
Side effects / Interactions	Not arm specified: intolerance or dislike of tea product (n=4)

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	25
Drop-out Number of participants who left the study for any reason or did not provide information on every data collection date	9
Drop-out reasons	Not arm specified lost to follow-up: no reasons for study discontinuation (n=4); intolerance or dislike of tea product (n=4); difficulty adhering to study protocol as a result of busy schedules (n=3)
Intervention	Citrus-based herbal placebo tea
Dosage and regime	Herbal tea product provided by Unilever, Lipton; 960ml daily (=4 tea bags, without EGCG); tea bags were placed in the provided tea mug and 240 mL of boiling water was added and allowed to steep for a period of 3 minutes + all participants: required to successfully complete a 2-week run-in period consisting of daily intake of 960 mL of herbal tea
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.	180
Side effects / Interactions	Not arm specified: intolerance or dislike of tea product (n=4)

Outcomes

Weight

Outcome type As specificed by the authors	Primary
Outcome specification	Body weight, height and waist and hip circumference were measured following standardised protocols (Khosla & Lowe, 1967; Lean et al., 1995)
Type of measurement	Scale
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".	NI
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".	The average body weight in the green tea arm was reduced by 1.2 kg compared to the baseline, whereas assignment to the placebo arm was associated with a slight rise in mean body weight of 0.2 kg over the same time period. These changes were not significant (p=0.23).

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	?

Body composition

Outcome type As specificed by the authors	Primary
Outcome specification	Body composition measurements (mean percentage body fat and lean mass) were assessed using dual energy X-ray absorptiometry (DXA) in accordance with standardised procedures under the direction of a certified radiation technician.
Type of measurement	DXA (Dual energy X-ray Absorptiometry)
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".	NI
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".	The BMI in the green tea arm was reduced by 0.5 kg/m2 after 6 month, the body fat percentage by 0.6%, the BMI in the placebo arm remained the same after 6 month , body fat percentage increased slightly by 0.4%, but these differences were not significant (p=0.22 for BMI, p=0.21 for body fat).

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	The work was supported by the National Susan G. Komen Foundation (breast cancer organisation) and the Arizona Cancer Center.
Conflicts of Interest	According to authors no conflict of interest

Further points for assessing the study

Sample

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

Alternative Explanation

Other explanations for an effect besides the investigated intervention
- 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
Correction for multiple testing	?
Measurement of compliance	?
Consistent reporting in numbers (figures, flowchart, abstract, results)	?
Comprehensive and coherent reporting	?
Cross-over
- 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
• Run-in period
• Control of treatment adherence (by using daily tea logs and participants had to return all used and unused tea bags to the clinic, compliance was very good with > 94% in both arms)
• Testing the flavour comparability of the teas (even if only with n=6)
• Control of general food intake via AFFQ and inclusion in analysis
• Testing for normal distribution of the data (baseline)

CONTRA:

• Overall small sample size
• High attrition
• Per-protocol analysis (intention-to-treat would be better)