| Reference ↗
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| Title
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Influence of vitamin C on salivary absorbed dose of 131I in thyroid cancer patients: a prospective, randomized, single-blind, controlled trial
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| Topic
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Vitamin C
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| Author
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Liu, B, Kuang, A, Huang, R, Zhao, Z, Zeng, Y, Wang, J, Tian, R
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| Year
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2010
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| Journal
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Journal of nuclear medicine
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| DOI
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http://dx.doi.org/10.2967/jnumed.109.071449
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Study Note
Brief summary
In this study, four different arms of thyroid cancer patients were examined, each beginning at different times to suck dissolved vitamin C in addition to radioiodine therapy to stimulate saliva flow (1, 5, 13, or 25 hours after radioiodine therapy). The aim of the vitamin C administration was to accelerate the excretion of radioiodine from the salivary glands by stimulating saliva flow, thereby protecting the salivary glands. The authors found no significant differences between the four arms regarding the radioactive exposure of the salivary glands. A drawback of this study is the absence of a control group that received no vitamin C at all. Therefore, this study only indicates that there are no differences regarding the timing of vitamin C administration.
In dieser Studie werden vier verschiedenen Gruppen mit Schilddrüsenkrebs untersucht, die zu verschiedenen Zeitpunkten beginnen, zusätzlich zur Radiojodtherapie gelöstes Vitamin C zu saugen, um den Speichelfluss zu stimulieren (1, 5, 13 oder 25 Stunden nach der Radiojodtherapie). Das Ziel der Vitamin C-Gabe war, über die Stimulation des Speichelflusses die Ausscheidung des Radiojods aus den Speicheldrüsen zu beschleunigen und damit die Speicheldrüsen zu schützen. Die Autoren fanden keine bedeutsamen Unterschiede zwischen den vier Gruppen hinsichtlich der radioaktiven Exposition der Speicheldrüsen. Ein Nachteil dieser Studie ist, dass keine Kontrollgruppe vorhanden ist, die überhaupt kein Vitamin C bekommen hat. Somit sagt diese Studie nur aus, dass es keine Unterschiede gibt, zu welchem Zeitpunkt Vitamin C gegeben wird.
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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Single
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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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4
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Study characteristics
| Inclusion criteria
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18 y old, case of recently diagnosed differentiated papillary or follicular thyroid cancer, undergone total thyroidectomy, referred to the Department of Nuclear Medicine, West China Hospital, for ablation of remnant thyroid tissue, stage pT1–T3, N0–N1, M0. For women of childbearing potential: a negative result on serum human chorionic gonadotropin pregnancy testing required
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| Exclusion criteria
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Presence of distant metastases; a previous history of salivary gland disorders, collagen tissue disease, diabetes, previous 131I therapy, or external radiation to the head or neck; or difficulty drinking a large amount of water.
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| N randomized
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80
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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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PP Analysis
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| Specifications on analyses
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NI
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| Countries of data collection
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China
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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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A: 1 hour after ingestion of 131I
B: 5 hours after ingestion of 131I
C: 13 hours after ingestion of 131I
D: 25 hours after ingestion of 131I
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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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NI
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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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Head and Neck Cancers - Thyroid 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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pT1–T3, N0–N1, M0
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| Comorbidities
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NI
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| Current cancer therapies
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Radioiodine treatment
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| Specifications on cancer therapies
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Radioiodine therapy (131I)
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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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Number n (Male/Female):
Arm A: 2/16
Arm B: 3/15
Arm C: 7/12
Arm D: 2/15
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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)
Arm A: 44 (14)
Arm B: 42 (14)
Arm C: 43 (13)
Arm D: 39 (12)
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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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20
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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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2
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| Drop-out reasons
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Did not complete salivary dosimetry measurements
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| Intervention
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Sucking vitamin C at 1 hour after ingestion of 131I
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| Dosage and regime
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100 mg every 4 h in the daytime over 6 d
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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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6
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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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Intervention
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| Number of participants (arm) N randomized
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20
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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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2
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| Drop-out reasons
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Showed distant metastases on posttherapy scans
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| Intervention
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Sucking vitamin C at 5 hours after ingestion of 131I
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| Dosage and regime
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100 mg every 4 h in the daytime over 6 d
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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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6
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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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Intervention
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| Number of participants (arm) N randomized
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20
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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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1
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| Drop-out reasons
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Showed distant metastases on posttherapy scans
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| Intervention
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Sucking vitamin C at 13 hours after ingestion of 131I
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| Dosage and regime
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100 mg every 4 h in the daytime over 6 d
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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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6
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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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Intervention
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| Number of participants (arm) N randomized
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20
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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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3
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| Drop-out reasons
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Did not complete salivary dosimetry measurements
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| Intervention
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Sucking vitamin C at 25 hours after ingestion of 131I
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| Dosage and regime
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100 mg every 4 h in the daytime over 6 d
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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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6
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| Side effects / Interactions
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NI
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Outcomes
Salivary gland function
| Outcome type As specificed by the authors
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Primary
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| Outcome specification
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Salivary activity
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| Type of measurement
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Scintigraphy
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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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No data available
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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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No data available
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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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Salivary gland function
| Outcome type As specificed by the authors
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Primary
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| Outcome specification
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Salivary absorbed sose, calculated from the 131I activity administered, saliva retention time and salivary gland mass (determined by CT)
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| Type of measurement
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CT (Computed Tomography)
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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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Single parotid gland: no differences between arms (p=0.37)
Single submandibular gland: no differences between arms (p=0.28)
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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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NA
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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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Salivary gland function
| Outcome type As specificed by the authors
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Primary
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| Outcome specification
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Salivary cumulated activities in first 24h after 131I ingestion divided by total cumulated activities
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| Type of measurement
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Scintigraphy
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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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Parotid gland: no differences between arms (p=0.21)
Submandibular gland: no differences between arms (p=0.16)
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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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NA
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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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Salivary gland function
| Outcome type As specificed by the authors
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Primary
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| Outcome specification
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Salivary absorbed dose during the first 24 h after 131I ingestion, calculated from the 131I activity administered, saliva retention time and salivary gland mass (determined by CT)
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| Type of measurement
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CT (Computed Tomography)
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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".
|
Parotid gland: no differences between arms (p=0.32)
Submandibular gland: no differences between arms (p=0.24)
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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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NA
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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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| 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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| Bias in selection of the reported result
|
?
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| Other sources of bias
|
?
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| Overall RoB judgment
|
?
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Funding and Conflicts of Interest
| Funding
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This work was supported by the National Natural Science Fund of China (grants 30670585 and 30870724).
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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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?
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| - Sample size corresponds to power analysis
|
|
| - Reasons for insufficient sample size based on power analysis
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| 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
|
|
| - Possibility of attention effects
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?
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| - Possibility of placebo effects
|
?
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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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| Consistent reporting in numbers (figures, flowchart, abstract, results)
|
?
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| Comprehensive and coherent reporting
|
?
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| Cross-over
|
|
| - Sufficient washout period
|
?
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| - Tested for carry-over effects
|
?
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| - Tested for sequence effects
|
?
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Interpretation of results
| Effect sizes reported (clinical vs. statistical significance)
|
?
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| Side effects systematically recorded
|
?
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| Side effects considered in result interpretation
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?
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| Ethics votum
|
?
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Additional Notes
PRO: Low dropout, evenly distributed per arm
CONTRA: Very small sample size per arm; No comparison sample without vitamin C; Only a few baseline characteristics investigated (no information to cancer stage); arm differences possible.
