Study Note
Brief summary
In this study, bladder cancer patients were examined with regard to the occurrence of recurrences after surgery, with half of the patients taking vitamin E daily and the other half taking nothing. There were significantly fewer recurrences in the vitamin E arm (19% vs. 36%) than in the control arm. There were no differences in the time to recurrence. This study is of very poor methodological quality. Among other things, only a small sample was examined without calculating whether the number was sufficient for the calculations. The study had a very poor overall reporting quality (e.g. the results section was sometimes very difficult to understand).
In dieser Studie wurden Blasenkrebskarzinom-Patienten hinsichtlich des Auftretens von Rezidiven nach der OP untersucht, wobei die Hälfte der Patienten täglich Vitamin E einnahm und die andere Hälfte nichts. In der Vitamin E-Gruppe fanden sich bedeutsam weniger Rezidive (19% vs. 36%) als in der Kontrollgruppe. Keine Unterschiede fanden sich bezüglich des Zeitraums bis zum Auftreten des Rezidivs. Diese Studie ist von sehr schlechter methodische Qualität. Es wurde unter anderem nur eine kleine Stichprobe untersucht, ohne zu berechnen, ob die Anzahl für die Berechnungen ausreichend ist. Die Studie hatte insgesamt eine sehr schlechte Berichtqualität (z.B. waren der Ergebnisteil teilweise sehr schlecht nachzuvollziehen).
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
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Prospective
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| Monocentric / Multicentric Monocentric: conducted in one center/ hospital; </br>Multicentric: conducted in multiple centers/ hospitals
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Monocentric
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| 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
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No
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| Is randomized
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Yes
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| Cross-over Participants alternate between different treatment groups or conditions over a specified period, allowing each participant to serve as their own control
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No
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| Number of arms
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2
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Study characteristics
| Inclusion criteria
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Patients diagnosed with a single, low‑grade, superficial bladder tumor, less than 3 cm in
diameter, who had undergone TUR
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| Exclusion criteria
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Accompanying carcinoma in situ (CIS)
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| N randomized
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46
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| 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.
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NI
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| Specifications on analyses
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NI
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| Countries of data collection
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Iran
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| LoE Level of evidence
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2b Oxford 2009
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| Outcome timeline Data collection times
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Year 1-2 examined every 3 months, then every 6 months
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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.
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No therapy setting
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| Types of cancer "Other Cancers" means that only a subpopulation was specified, but further unspecified cancer types were included
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Genitourinary Cancers - Bladder Cancer
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| 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
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Early Stage
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| Specifications on cancer stages
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Diameter < 3 cm
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| Comorbidities
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NI
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| Current cancer therapies
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No therapy
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| Specifications on cancer therapies
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No intravesical chemotherapy
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| Previous cancer therapies
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Surgery
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| Gender
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Mixed
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| Gender specifications
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89.1% female
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| Age groups
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Adults (18+)
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| Age groups specification
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Mean (SD) = 59.8 (12.5) years
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Arms
| Arm type Active control: group receives active treatment; </br>Passive control: for example treatment as usual, waiting control, no treatment
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Intervention
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| Number of participants (arm) N randomized
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21
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| Drop-out Number of participants who left the study for any reason or did not provide information on every data collection date
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NI
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| Drop-out reasons
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"Patients without regular follow‑up or medication intake were excluded form the study." No information on number of drop-outs (if any) given.
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| Intervention
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Vitamin E
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| Dosage and regime
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Oral, 400IU, 1x daily
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| One-time application
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No
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| 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.
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-999
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| Side effects / Interactions
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NI
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| Arm type Active control: group receives active treatment; </br>Passive control: for example treatment as usual, waiting control, no treatment
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Passive control
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| Number of participants (arm) N randomized
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25
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| Drop-out Number of participants who left the study for any reason or did not provide information on every data collection date
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NI
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| Drop-out reasons
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NI (no information on possible drop-out given)
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| Intervention
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None
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| Dosage and regime
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NA
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| One-time application
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No
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| 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.
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-999
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| Side effects / Interactions
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NA
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Outcomes
"Bladder ultrasound" is not in the list (AQoL-8D (Assessment of Quality of Life), ASAT (Auditory Sustained Attention Test), BIA (Bioelectrical impedance analysis), BPI-SF (Brief Pain Inventory - Short Form), CTCAE (Common Terminology Criteria of Adverse Events), ESAS (Edmonton Symptom Assessment Scale), FAACT (Functional Assessment of Anorexia-Cachexia Therapy), FACIT (Functional Assessment of Chronic Illness Therapy), FLIE (Functional Living Index for Emesis), Genitourinary atrophy self-assessment tool, ...) of allowed values for the "Type of measurement" property.
Recurrence rate
| Outcome type As specificed by the authors
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Primary
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| Outcome specification
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Occurrence of recurrences
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| Type of measurement
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Cystoscopy, Ultrasonography, Urinalysis
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| 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".
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NA
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| 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".
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Overall:
Number in %
intervention arm: 19, control arm: 36; RR = 0.53 (95% CI 0.19 – 0.92); OR = 0.42 (95% CI: 0.19, 0.92); p = 0.04, sign.
Recurrences in the first year:
intervention arm: 66.7% of recurrences, control arm: 75% of recurrences
Time to recurrence in months (mean (SD)):
intervention arm: 9 (8.1), control arm: 8.33 (6.1); p = 0.9, not sign.
Separated by smoking status:
Smokers: intervention arm: 25%; control arm: 50%; p = 0.06
Non-smoker: intervention arm: 15.4%; control arm: 26.7%; p = 0.15
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| Risk of Bias Assessment: Cochrane RoB tool 2.0
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| Bias arising from the randomization process
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?
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| Bias due to deviation from intended intervention (assignment to intervention)
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?
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| Bias due to deviation from intended intervention (adhering to intervention)
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NA
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| Bias due to missing outcome data
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?
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| Bias in measurement of the outcome
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?
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| Bias in selection of the reported result
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?
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| Other sources of bias
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?
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| Overall RoB judgment
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?
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Funding and Conflicts of Interest
| Funding
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NI
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| Conflicts of Interest
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NI
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Further points for assessing the study
Sample
| Power analysis performed
|
?
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| - 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)
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?
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| Ethnicity mentioned
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?
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Alternative Explanation
| Other explanations for an effect besides the investigated intervention
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|
| - Possibility of attention effects
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?
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| - Possibility of placebo effects
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?
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| - Other reasons
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?
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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
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?
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| Measurement of compliance
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?
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| Consistent reporting in numbers (figures, flowchart, abstract, results)
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?
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| Comprehensive and coherent reporting
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?
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| Cross-over
|
|
| - Sufficient washout period
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?
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| - Tested for carry-over effects
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?
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| - Tested for sequence effects
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?
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Interpretation of results
| Effect sizes reported (clinical vs. statistical significance)
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?
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| Side effects systematically recorded
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?
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| Side effects considered in result interpretation
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?
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| Ethics votum
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?
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Additional Notes
