Ellen Conte,1,2 ND, Erica Rizzolo,1,2 ND, Gillian Flower,1 ND, Mark Legacy,1,2 BSc, and Dugald Seely,1,2 ND, MSc
ABSTRACT
Intravenous vitamin C (IVC) is a common therapy used by naturopathic doctors and other licensed integrative practitioners. With several proposed mechanisms of action related to cancer care, it is often used in integrative oncology settings. Despite its common use, there are no published evidence-based resources on the efficacy, safety, and procedural considerations for the use of IVC in practice. The objectives of this review are to summarize the evidence on high-dose IVC in supportive cancer care and to provide a resource of practical clinical guidance for IVC application. In cancer care, IVC is most commonly used at doses high enough to achieve a potential cancer cell cytotoxicity. This review focuses on IVC at doses of ≥15 g which we have defined as high-dose. To date, there are 23 published clinical trials evaluating the use of high-dose IVC in cancer support. Based on data from these clinical studies, IVC used concurrently with oxidative therapies, such as chemotherapy and radiotherapy, seems to produce the greatest likelihood for improvements in quality of life and additive anti-tumour effects compared with IVC as monotherapy or with non-oxidative therapies. IVC has shown promise in improving quality of life in patients with breast cancer and advanced pancreatic and ovarian cancers. Limited evidence suggests survival and/or tumour response may be improved with the inclusion of IVC in patients with advanced pancreatic cancer, non-small cell lung cancer, and RAS-mutated colorectal cancer. IVC does not offer curative potential, and further research is needed to explore its effectiveness relevant to mortality outcomes. Practical guidance including assessment, monitoring, dosing, safety, and communication with other healthcare providers is discussed.
Key Words Supportive cancer care, intravenous therapy, naturopathic medicine
Intravenous vitamin C (IVC) gained interest as a therapy for cancer after studies published by Cameron, Campbell, and Pauling in the 1970s suggested it could improve outcomes.1–3 However, subsequent controlled trials using oral supplementation showed no benefit,4,5 and vitamin C received minimal attention for the next couple of decades. Following additional research and a better understanding of the differences between oral and IV administration, interest in IVC was renewed in the early 2000s.
IVC is commonly used by naturopathic and integrative practitioners in the integrative oncology setting. An observational study of people with breast cancer being treated by naturopathic doctors (NDs) in Washington State reported that 12.3% of patients were treated with IVC, making it the most commonly used injectable therapy in this cohort.6 A survey of complementary and integrative medicine practitioners published in 2010 reported that 172/199 respondents administered IVC,7 although this included indications related to conditions outside of cancer. Finally, data from the Canadian/US Integrative Oncology Study (NCT02494037), the largest observational study of integrative oncology administered by NDs in North America, found that IVC was recommended to 67% of patients with advanced-stage cancer (Mark Legacy, Study Coordinator, email communication, April 2023). These data are set to be published in 2024.
IVC has been studied in a range of doses for people with cancer. The effects likely differ based on dose, as only higher doses have been shown to achieve the proposed pro-oxidative and cytotoxic effects. There is no accepted definition of low-dose versus high-dose IVC, as the exact dose whereby these effects occur is unknown. A dose of 15 g was decided on by the authors as qualifying as high-dose based on 2 factors. Firstly, a 15 g dose is expected to achieve plasma concentrations between 2 and 5 mM,8 thus reaching pro-oxidant and cytotoxic levels for some, but not all cell lines, as demonstrated in preclinical research.9,10 Secondly, 15 g is a common cut-off dose for safety when glucose 6 phosphate dehydrogenase (G6PD) enzyme status is unknown or deficient. Deficiency in this enzyme can lead to hemolytic anemia due to impaired clearance of hydrogen peroxide, indicating a pro-oxidative process is occurring. This is discussed further in the safety section.
Given the use of IVC in cancer settings, NDs and other integrative practitioners should be aware of the evidence around efficacy and safety. This narrative review provides an up-to-date evidence-based resource for integrative practitioners on the use of IVC in cancer populations.
Several mechanisms of action have been proposed for IVC in cancer care. These include IVC generating a pro-oxidant effect, enzyme cofactor activities, anti-inflammatory activities, immune effects, and correcting hypovitaminosis C.
Although vitamin C acts as an antioxidant via the donation of electrons, high concentrations can cause the formation of hydrogen peroxide (H2O2), which has a pro-oxidant effect inducing cytotoxicity by pyknosis and/or necrosis.9,11,12 This is thought to impact cancer cells more than healthy cells; the tumour microenvironment contains more free transition metal ions, which allows more H2O2 to be produced, and cancer cells lack enzymes such as catalase, glutathione peroxidase, and peroxiredoxin-2 to break down H2O2.13 Preclinical studies have found this pro-oxidant and cytotoxic effect to occur at plasma concentrations that range from 1 mM to greater than 20 mM, depending on the tumour cell line evaluated.9,10
Vitamin C exerts various effects on transcription factors and cell signaling pathways, which can affect the cell cycle, angiogenesis, and cell death pathways, even at concentrations achievable through oral administration.14 As a cofactor for collagen synthesis, in vivo studies have found increased collagen encapsulation and decreased metastases in cancer models with low-dose vitamin C.15–17 Vitamin C is a cofactor for various hydroxylases and histone demethylases that regulate gene transcription.15 High-dose IVC may be able to reduce expression of tumour hypoxia-inducible factors (HIF) as demonstrated in a small clinical trial in colon cancer.18 Vitamin C may therefore be involved in epigenetic changes by acting as an enzyme cofactor.
Studies in adults with cancer using IVC have found reductions in several inflammatory markers, including C-reactive protein, erythrocyte sedimentation rate,19,20 neutrophil-to-lymphocyte ratio,21 and F2-isoprostanes.22 This is particularly important and highlights an indication for use of IVC in cancer settings, given that those with cancer are documented to have increased inflammation.23
Two human studies found an increase in T-lymphocytes with the use of IVC,21,24 which may favour anti-tumour immune function.25 This corroborates preclinical data, which demonstrate a positive impact on the function of lymphocytes and natural killer cells.25–27
Adults with cancer, and particularly those with advanced disease, are at risk of hypovitaminosis C (plasma levels <28 μmol/L).23 This is multifactorial, but likely driven by increased oxidative stress and inflammation, which increases the rate of utilization of vitamin C.23 Hypovitaminosis C can cause ill-effects, including fatigue, myalgia, impaired wound healing, edema, and ecchymoses, thus impacting quality of life and physical health.23
Administration of IVC results in far higher serum ascorbate levels than oral administration of an identical dose28,29 as it bypasses gastrointestinal limitations to absorption.11 Pharmacologic concentrations of serum ascorbate are defined as 0.3 mM and higher, which are achievable through IV administration but not through oral ingestion.9,12 Pharmacologic concentrations of ascorbate exhibit first-order elimination kinetics.30 The elimination half-life is short, ranging from 30–120 minutes30–33 through renal excretion;9,33 thus, concentrations in the theoretical cytotoxic range are not maintained for long.
A pharmacokinetic study from 2021 found that serum ascorbate levels started to plateau at IVC doses over 75 g (around 1 g/kg in the study population) in both healthy and cancer populations;33 thus, higher doses may have diminishing returns. In this study, the maximum serum concentration (Cmax) at a 75-g dose in the healthy population was 24.9 mM and in the cancer population was 21.6 mM. This is generally consistent with previous studies, which used doses ranging from 1 to 1.5 g/kg (typically correlating to doses of 60–100 g) to achieve serum concentrations around 20 mM.12,22,34–40 Vitamin C pharmacokinetics are impacted by tumour burden and baseline serum levels. It has been demonstrated that those with advanced disease may require higher doses to achieve similar serum levels, possibly due to lower baseline levels and higher inflammation and oxidative stress.23,41
Twenty-three clinical trials, including one placebo-controlled randomized controlled trial (RCT), four non-placebo-controlled RCTs, and 18 single-arm trials, have been published for high-dose IVC (defined here as ≥15 g) and cancer. Findings from these studies are reported in Table 1. A variety of cancer types have been studied; the most studied (by number of participants) are breast, lung, prostate, ovarian, colorectal, and pancreatic cancer. The main focus of this paper is high-dose IVC as doses <15 g are not likely to achieve plasma levels in the theoretical cytotoxic range as described above. However, several studies have evaluated low-dose IVC (<15 g). These are reported separately in Table 2 but will not be discussed further.
TABLE 1 Clinical Trials of High-Dose (>15 g) Intravenous Vitamin C for Cancer
TABLE 2 Clinical Trials of Low-Dose (<15 g) Intravenous Vitamin C for Cancer
When used alongside conventional cancer treatments, clinical trial data demonstrate mixed results for the impact of IVC on quality of life (QoL) or treatment toxicity. Studies of IVC in breast,42 pancreatic,22 and ovarian43 cancers have reported benefits in these outcomes, whereas studies in colorectal,44 prostate,38 and mixed cancers37 have reported no benefit. Observational studies have been more supportive of IVC, with two studies evaluating breast cancer45,46 and one in mixed cancers,47 all showing benefit. Data from studies using IVC as monotherapy show similar findings; in three small single-arm trials of patients with mixed types of advanced cancers, QoL remained stable in two32,35 and improved in another.48 Given the advanced stage of these patients, stable QoL may be a desirable outcome; however, without a control group, these outcomes are difficult to interpret.
Three studies used IVC in combination with another integrative intervention and evaluated QoL outcomes. The first two studies used IVC with modulated electrohyperthermia (mEHT) in patients with advanced non–small cell lung cancer (NSCLC).34,49 One was a phase I study using IVC and mEHT in patients refractory to standard treatments and noted symptom subscale improvements at 4 weeks in fatigue, dyspnea, insomnia, appetite, diarrhea and financial problems.34 The second was a phase II study by the same authors, and they noted varying QoL improvements compared with best supportive care only. Incidence of peripheral neuropathy was lower in the IVC plus mEHT group.49 The third study used IVC with a ketogenic diet in patients with advanced cancers and noted decreases in inflammatory markers.20 Due to the multimodal interventions, it is difficult to know what impact IVC had compared with the other treatments.
Due to the small number of studies, heterogeneity in outcome measures used (e.g., patient-reported outcome measures, physician-assessed symptoms, performance status, blood tests), and mixed results, it is not possible to state what specific symptoms, toxicities, or aspects of QoL may improve with the use of IVC. From studies reported in Table 1, there have been noted improvements for specific symptoms (including nausea, dyspnea, insomnia, loss of appetite, weight loss, pain, fatigue, and neurotoxicity),42,50,51 performance status,51,52 and blood tests (including hematological toxicities such as anemia, leukopenia, and thrombocytopenia, inflammation, and liver and kidney function).51,53
Although some research indicates IVC may help improve patient QoL, there is still equipoise from the published research. More rigorous and well-controlled clinical trials are needed to clarify the impact of IVC on QoL and treatment side effects. No studies have reported worsening QoL or increased treatment toxicity with the use of IVC.
Two RCTs,43,44 nine single-arm trials,15,22,37–40,54–56 and two observational trials46,57 have evaluated survival and tumour response rates for IVC concurrent with conventional care. The clinical trials are described in Table 1. Given that the majority of these studies are single arm, evaluating the impact on these outcomes is difficult. There is preliminary evidence that IVC may improve survival time and/or tumour response when combined with conventional treatment in pancreatic cancer,5,39,52,54 NSCLC,55 and RAS-mutant colorectal cancer;44 however, more research is needed to confirm these findings.
Clinicians should be aware of the two RCTs that have assessed IVC for treatment outcomes. The first was a non-placebo controlled RCT in which 25 people with stage III or IV ovarian cancer receiving carboplatin and paclitaxel were randomized to IVC or control.43 The median time to disease progression was 8.75 months longer in the treatment arm compared with the control, but the results were not statistically significant (no p value was calculated by the authors).43 The second RCT was also not placebo controlled and evaluated 442 patients with metastatic colorectal cancer randomized to FOLFOX ± bevacizumab with or without IVC.44 There were no significant differences in objective response rates, median progression-free survival (PFS), or overall survival between groups; however, a sub-analysis revealed that patients with a RAS mutation had significantly longer PFS (9.2 vs. 7.8 months, hazard ratio [HR] 0.67; 95% confidence interval [CI]: 0.50–0.91; p = 0.01) with IVC and chemotherapy versus chemotherapy alone.
Four clinical trials have evaluated IVC as monotherapy for cancer treatment; three failed to demonstrate an objective tumour response 32,35,58 and one found a modest response.59 All four trials included people with advanced or terminal cancers refractory to conventional therapies. It is important for clinicians to know that IVC monotherapy is not considered a curative cancer treatment.
Finally, two studies used IVC as part of a multimodal integrative intervention and evaluated survival time. One RCT used IVC with mEHT in patients with advanced NSCLC,49 and a second controlled observational study used IVC with an alkaline diet and bicarbonate alongside chemo-radiation.60 In both studies, survival time was superior for those in the treatment arm compared with the control arm. Due to the multimodal intervention, it is difficult to know what impact IVC had compared with the other treatments.
No studies have reported worsening response rates or survival outcomes with the use of IVC.
No studies have evaluated IVC as a treatment to reduce the risk of developing cancer or cancer recurrence. Thus, using IVC as a prevention strategy is not recommended based on current evidence.
Most studies in cancer have used IVC alongside conventional cancer treatments, primarily chemotherapy. Of the 23 clinical trials identified for high-dose IVC (Table 1), only seven evaluated IVC as a monotherapy; six were single-arm30,32,35,48,58,59 and one was an RCT.18 The findings of studies that have used IVC as monotherapy have generally been unremarkable; however, it must be noted that these studies also enrolled patients with advanced disease who had often exhausted conventional treatment options. Good outcomes for any intervention are unlikely in this heavily pretreated population. Nonetheless, it is important for practitioners to realize that the most evidence-based approach to the use of IVC is one which combines it with conventional cancer treatments, particularly chemotherapy.
The majority of IVC studies, as documented in Table 1, report only mild side effects and collectively demonstrate a positive safety profile for doses up to 1.5 g/kg three times per week.32,35,58 This clinical data is supported by observational and survey data.7,61 A low adverse event rate was documented through a large survey of practitioners who use this therapy (101/9328 infusions, or 1.0%).7 A retrospective review of all patients receiving IVC at Thomas Jefferson University Hospital over a 7-year period included 86 people who received a total of 3,034 doses of IVC ranging from 50 to 150 g.61 Adverse events were reported in less than 5% of all infusions and less than 3% in patients receiving IVC alone.
Based on the literature, including the clinical trials reported in Table 1, observational studies,61 a large clinician survey,7 and the clinical experience of the authors, the following adverse events are expected among patients receiving IVC. Many of these side effects may be attributed to the infusion of a high osmolarity solution. Further, many of these reactions appear to be mitigated by drinking fluids before and during treatments.35,54,58
A few case reports cite vitamin C intake as a cause of kidney stones and renal failure;58,62–64 however, larger prospective studies do not support this association in patients who do not have a history of these conditions.65,66 Oxalic acid excretion is transiently increased in a dose-dependent fashion by IVC treatment, but this is not suspected to contribute significantly to stone formation in patients without a clinical history.67 It is recommended that IVC not be administered to patients with renal failure who may be predisposed to hyperoxalemia or hyperoxalosis,64,68,69 as this population could be at increased risk for stone formation or oxalate nephropathy from IVC treatment.69–71 Additionally, caution is recommended in patients with a history of kidney stone formation or compromised renal function. Although there is no definitive cut-off for renal function, creatinine levels >175 μmol/L or eGFR <45 mL/min have been proposed and are a rational approach.23,64,67,69
Cases of potentially fatal hemolytic anemia have been reported when high doses of IVC are administered to individuals with a deficiency of G6PD.72,73 A deficiency of this enzyme causes plasma H2O2 levels to rise when high doses of vitamin C are administered, leading to destruction of healthy cells. The common convention is to avoid doses of vitamin C exceeding 15 g in those with unknown or deficient G6PD status, although data to support the cut-off dose are lacking.
IVC administration will elevate fingerstick blood glucose monitor readings in most portable glucometers.74,75 Those with diabetes must be informed of this and be advised that insulin must not be administered on the basis of post-treatment glucometer readings. Glucometer readings should not be relied on for accurate blood sugar measurements until approximately 8 hours after IVC administration.
Patients with hemochromatosis should avoid excessive vitamin C intake,76 although the effect of IVC has not been studied in this population and the risk is hypothetical. IVC may be used to mobilize iron stores in the treatment of functional anemia among hemodialysis patients and may actually reduce ferritin stores.77 If IVC is administered to individuals with iron storage diseases, monitoring of iron status is recommended.
IVC is administered as a hypertonic solution and typically infused in 500 mL or more of fluid. The high osmolarity implies cautions similar to those of other osmotic diuretics; thus, it may not be suitable for patients with dehydration or anuria. The fluid volume may make IVC unsuitable for those with severe pulmonary congestion, ascites, edema, or low cardiac output.35
The safety of IVC has not been demonstrated in the mother, fetus, or newborn baby.
To date, there are no known negative interactions between commonly used cancer treatments and IVC based on clinical trial data. Human studies (described in Tables 1 and 2) have used IVC alongside a variety of cytotoxic chemotherapy and targeted agents, including gemcitabine, carboplatin, paclitaxel, cyclophosphamide, cytarabine, 5-fluorouracil, oxaliplatin, irinotecan, dexamethasone, temozolomide, erlotinib, rituximab, and bevacizumab. Preclinical studies have suggested the potential for a negative interaction between vitamin C and the targeted agent bortezomib.78 Despite the small clinical trial by Held at al.,79 which showed clinical benefit in 4/10 patients receiving low-dose IVC and bortezomib, caution with bortezomib and other boron-based proteasome inhibitors (e.g., iaxomib) is warranted until we have more definitive clinical evidence.
Based on antioxidant supplements being discouraged during radiation treatment, IVC was thought to have a theoretical interaction; however, it has been safely used concurrently with radiation therapy without any reported decreases in efficacy. Although most of these studies were small and without a control group, there was no indication of a negative interaction, and many reported results were suggestive of benefit. The data from studies with control groups have shown either no difference or improvements in response rates and survival time with concurrent use of IVC.43,44,55 See Table 1 for details on these studies.
Preclinical data corroborate the limited clinical data, suggesting a synergistic effect when some chemotherapy agents are combined with IVC. Chemotherapy agents with evidence of synergy combined with IVC include: gemcitabine,80 carboplatin,81 cisplatin,29,82,83 etoposide,29,82,83 5-fluorouracil,29,82,84 epirubicin,84 doxorubicin,29,83,85 paclitaxel,29,83 docetaxel,84 and irinotecan.84 In these studies, the combination of IVC plus chemotherapy was related to increased tumour inhibition and decreased tumour growth rate compared with either IVC or chemotherapy alone.
To date, very few studies have evaluated IVC with monoclonal antibodies86 or oral targeted therapies (e.g., tyrosine kinase inhibitors).54 Thus, the safety profile of IVC with these agents is not clear.
Although IVC has been commonly used by NDs and other integrative practitioners since the early 2000s, there remain significant gaps in the knowledge around its efficacy. Most studies to date have been small, single-arm, and heavily focused on safety and dosing. Thus, research on clinical effectiveness is sparse. More RCTs, particularly those with a placebo control, are needed. The Patterson Institute for Integrative Oncology Research, together with The Ottawa Hospital Research Institute, are conducting a double blind, placebo-controlled RCT of IVC in patients with incurable NSCLC. This study will help to address this gap, but studies in other cancer types are needed. A description of the trial is available at https://clinicaltrials.gov, NCT05849129.
There are no published clinical studies evaluating IVC with newer cancer agents, such as immunotherapy (e.g., PD1 and CTLA4 inhibitors) and cell-based gene therapies (e.g., CAR T-cell therapies) which are increasingly being used in cancer control. In terms of IVC in specific cancer populations, there is a lack of data on hematological malignancies and pediatric populations, as well as on early-stage disease; thus, whether there are benefits and in which populations the benefit is greatest are not known.
This section offers practical guidance for integrative practitioners providing IV therapy to patients with cancer, and specific considerations for IVC administration.
Providing IV care to individuals with a cancer diagnosis can present some unique challenges. Certain impacts of cancer and its treatment can affect the tolerance and suitability of IV therapy. Practitioners should be aware of the side effects and toxicities of chemotherapy and other conventional treatments, such as myelosuppression, renal toxicity, nausea and vomiting, and hypertension. Fluid management issues are also a consideration, including increased edema, ascites, hydronephrosis, and pleural effusion. Practitioners should be aware of these issues and know how to accommodate them. This section outlines considerations for monitoring patients with cancer receiving IVC.
Prior to initiating IVC, a physical exam is recommended to assess weight, fluid burden, cardiovascular and respiratory health, and general vital signs. Table 3 shows suggested minimum requirements for care. In general, patients with severely compromised vitals should not be administered IVC due to the potential presence of a condition which may require acute or emergency treatment.
TABLE 3 Recommended Vital Sign Requirements for Administering Intravenous Vitamin C
Overall functional status should also be assessed using a validated tool such as the Eastern Cooperative Oncology Group (ECOG) Performance Status Scale. It is recommended to only administer IVC to patients with an ECOG score of 3 or lower.
Table 4 describes suggested laboratory tests with suggested minimum requirements to initiate and maintain IVC treatment, as well as parameters for additional monitoring.
TABLE 4 Recommended Laboratory Requirements for Administering Intravenous Vitamin C
In addition to a baseline physical exam and laboratory testing, ongoing monitoring of laboratory tests, vital signs, weight, and functional status should be completed at regular intervals. Patients should be asked about new symptoms or treatments and tolerance of previous infusions at each visit. For example, rapid weight gain or loss should require evaluation for cachexia or ascites. In general, it is recommended that blood tests be repeated every 3 months. More frequent testing (e.g., monthly) is recommended in patients who have had recent results outside the parameters outlined in Table 4. These values are informed by the Common Terminology Criteria for Adverse Events, version 5.0.
IVC is typically administered 1 to 3 times weekly, with twice weekly being the most common dosing schedule in clinical trials. It is common for practitioners to dose IVC to achieve plasma concentrations around 20 mM. This is based on preclinical data which have shown that while some cancer cell lines exhibit apoptosis at concentrations as low as 1 mM of IVC, other cell lines require concentrations as high as 20 mM.9,10 Two commonly used methods of dosing IVC are a weight-based approach and the fingerstick glucose method (FSGM); both methods attempt to target the theoretical cytotoxic ascorbate concentrations.87 Weight-based approaches typically range from 1 to 1.5 g/kg of body weight (~50–125 g per infusion), which is common in clinical trials. As described in the pharmacokinetics section, doses around 1 g/kg have typically been found to achieve concentrations in the theoretical cytotoxic range.33 The FSBG method is used as an approximation of plasma ascorbate concentrations without correction.87 Dosing is escalated to achieve a 400 mg/dL (22.2 mmol/L) difference in patients’ glucometer readings pre- and immediately post-IV treatment. In addition to total dose, infusion rate also impacts peak plasma concentrations. Based on existing research, infusion rates ranging from 0.5 to 1.0 g/min are recommended..33,88
Patients may request IVC treatments expecting that this therapy can replace curative conventional options. It is important for clinicians to inform patients that IVC is not considered a curative treatment for cancer. An evidence-informed discussion with patients about treatment expectations should be conducted prior to the initiation of IVC treatment. This will allow patients to provide fully informed consent for IV care and help manage expectations with regard to treatment. In addition, treatment impacts should be reviewed with the clinician regularly. Treatment should be discontinued if no clinical evidence of benefit on disease progression or quality of life can be seen.
In addition, informed consent for an intervention that requires significant time and cost for the patient should be given thorough consideration given the potential of financial toxicity. While there may be benefit for patients that use this therapy, it is important not to overstate the evidence nor to create false expectations, particularly with respect to outcomes associated with prolonging survival. In determining utility, the perspective of the patient and their personal reasons for choosing such a therapy needs to be modulated by the evidence that exists and how it aligns with their clinical picture. To maintain informed consent, ongoing evaluation and discussion on continued use of this therapy is critical to preserve the goals of care and best interests of the patient.
IVC is not supported by all practitioners, and oncologists and other HCPs may raise concerns about its use. This issue is beyond the scope of this paper, but it is advisable for the conscientious practitioner to make efforts to bridge the gap among HCPs. One tool to support this process is writing a clinical consult note with the provision of evidence and rationale for the use of IVC, and providing consideration of how safety and clinical evaluation will be maintained. If integrative practitioners adhere to principles of care and jurisdiction-dependent regulatory framework, they will be in a solid place to provide ethical care that is centered on patient well-being. It is recommended that NDs review the Principles of Care Guidelines published by the Oncology Association of Naturopathic Physicians for further discussion on patient management and communication.89
IVC in the context of cancer is a developing and promising clinical application that deserves consideration in cases of active disease. Results from clinical trials demonstrate that IVC is generally well-tolerated, with minimal and mild side effects. Some, but not all, studies have found benefit for quality of life, symptom management, and treatment-related toxicities alongside cancer treatments and, to a lesser degree, as monotherapy. There is promising preliminary research for IVC administered in addition to standard treatments for tumour response and/or survival outcomes in advanced pancreatic cancer, NSCLC, and RAS-mutant colorectal cancers. The adjunctive use of IVC in cancer requires more rigorous research from larger, randomized, and placebo-controlled trials to confirm these findings and study its impact in other cancers. Within the context of thorough and ongoing informed consent, IVC has the potential to improve management of cancer. Judicious application with strategies to ensure safety is essential. Keeping abreast of new developments and research in the field is critical for any clinician practicing in integrative oncology settings, and especially necessary for a higher-cost and more invasive therapy like IVC.
Tips on access
IVs, blood draws and blood pressure measurements should not be conducted on the side of axillary lymph node removal.
Accommodations for people in treatment
Safety
1The Centre for Health Innovation, Ottawa, ON, Canada;
2The Canadian College of Naturopathic Medicine, Toronto, ON, Canada.
Not applicable
We have read and understood the CAND Journal’s policy on conflicts of interest and declare that we have none.
This research did not receive any funding
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Correspondence to: Dr. Dugald Seely, ND, MSc, 429 MacLaren Street, Ottawa, ON K2P 0M7, Canada. E-mail: dseely@thechi.ca
To cite: Conte E, Rizzolo E, Flower G, Legacy M, Seely, D. Intravenous vitamin C in cancer care: Evidence review and practical guidance for integrative oncology practitioners. CAND Journal. 2024;31(1):2-18. https://doi.org/10.54434/candj.149
Received: 30 June 2023; Accepted: 21 September 2023; Published: 21 March 2024
© 2024 Canadian Association of Naturopathic Doctors. For permissions, please contact candj@cand.ca.
CAND Journal | Volume 31, No. 1, March 2024