Breast Cancer Chemotherapy (paclitaxel) 6X more likely to be painful if low Vitamin D
Pre-treatment vitamin D insufficiency predicts severe paclitaxel-induced sensory neuropathy in breast cancer patients: a prospective cohort study
Sci Rep. 2026 May 5;16(1):14282. doi: 10.1038/s41598-026-50367-8.
Amany M Elfeky 1, Muhammad I El-Masry 2, Amr A Mahmoud 1, Sara A Amin 1, Rana El Falah 3, Mo'men M Saadoun 4
Paclitaxel-induced peripheral neuropathy (CIPN) is a debilitating side effect affecting up to 70% of patients receiving paclitaxel chemotherapy, with severe symptoms occurring in approximately 30%. While non-modifiable risk factors such as age and genetics have been established, the role of modifiable factors, including vitamin D insufficiency, remains poorly characterized. This study aimed to evaluate the association between pre-treatment vitamin D levels and the incidence of severe CIPN in breast cancer patients receiving paclitaxel-based chemotherapy. A prospective cohort study was conducted on 300 breast cancer patients (stage I-III) receiving paclitaxel-based chemotherapy (80 mg/m²) for 12 weeks at Kafrelsheikh University Hospitals. Baseline serum 25(OH)D was quantified using the Elecsys Vitamin D Total II assay on the Cobas e411 platform, standardized to the VDSP reference method. Pre-treatment vitamin D levels were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS), with insufficiency defined as ≤ 20 ng/mL. CIPN was assessed using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Chemotherapy-Induced Peripheral Neuropathy 20-item scale (EORTC QLQ-CIPN20), with particular focus on grade 3-4 sensory neuropathy. Statistical analyses included receiver operating characteristic (ROC) curves and multivariate logistic regression to identify independent risk factors. The mean pre-treatment vitamin D level was 23.45 ± 8.3 ng/mL, with 39.3% (118/300) of patients classified as having vitamin D insufficiency.
Patients with vitamin D insufficiency demonstrated significantly higher rates of grade 3-4 sensory CIPN compared to those with sufficient levels (32.2% vs. 5.5%, p < 0.001). Mean vitamin D levels were significantly lower in patients who developed severe CIPN (17.5 ± 4.9 ng/mL vs. 24.6 ± 8.4 ng/mL, p < 0.001). ROC analysis demonstrated vitamin D's predictive value for motor CIPN (AUC = 0.747, p = 0.038).
Multivariate logistic regression analysis confirmed vitamin D insufficiency as an independent predictor of sensory CIPN (OR = 6.72, 95% CI: 3.09-14.61, p < 0.001), even after adjusting for age, body mass index, and treatment schedule.
Vitamin D insufficiency is independently associated with an increased risk of severe paclitaxel-induced peripheral neuropathy in breast cancer patients. While causal inference cannot be drawn from this observational design, these findings provide a strong rationale for future randomized controlled trials to evaluate whether vitamin D supplementation could serve as a candidate preventive strategy to mitigate CIPN severity and optimize cancer therapy outcomes.
Keywords: Breast cancer; Chemotherapy-induced peripheral neuropathy; Neuroprotection; Paclitaxel; Risk factors; Vitamin D insufficiency.
Future research directions
Our findings highlight several important avenues for future research. First, randomized controlled trials are urgently needed to determine whether vitamin D supplementation can prevent or reduce the severity of paclitaxel-induced neuropathy. Such trials should employ adequate vitamin D dosing regimens (likely 2000 - 4000 IU daily or weekly equivalent doses) initiated several weeks before chemotherapy to allow for repletion of vitamin D stores. Target levels of 30-40 ng/mL should be achieved prior to chemotherapy initiation.
- Second, mechanistic studies are needed to elucidate the specific pathways through which vitamin D exerts neuroprotective effects in the context of taxane exposure. This could include assessment of inflammatory biomarkers, oxidative stress markers, nerve growth factors, and evaluation of vitamin D’s effects on paclitaxel- induced mitochondrial dysfunction and microtubule disruption in peripheral neurons.
- Third, investigation of gene-environment interactions between vitamin D receptor polymorphisms and vitamin D status may help identify patient subgroups most likely to benefit from supplementation. Similarly, studies examining whether vitamin D status modifies the relationship between paclitaxel pharmacokinetics and the risk of neuropathy could provide insights into dose optimization strategies.
- Fourth, extension of our findings to other neurotoxic chemotherapy agents (platinum compounds, vinca alkaloids, proteasome inhibitors) would help establish whether vitamin D’s neuroprotective effects are specific to taxanes or represent a broader phenomenon applicable to multiple drug classes.
- Fifth, the repeated CIPN assessments in our cohort provide a rich longitudinal dataset amenable to trajectory modeling approaches, such as latent class growth analysis or group-based trajectory modeling. Such analyses could identify distinct patterns of neuropathy evolution and patient subgroups with divergent trajectories, potentially refining risk stratification beyond dichotomized severity endpoints.
- We plan to pursue these analyses in a dedicated follow-up study.Ultimately, economic analyses evaluating the cost-effectiveness of universal vitamin D screening and supplementation compared to targeted approaches or no intervention would inform implementation strategies and health policy decisions.
It appears that low vitamin D increases the risk of pain associated with paclitaxel. Is this true?
Claude AI May 2026
Yes, this appears to be well-supported by recent evidence, including a validated finding from a major clinical trial.
The strongest evidence comes from a 2023 analysis of the SWOG S0221 trial, a phase III study of early-stage breast cancer patients receiving paclitaxel. Among ~1,191 women, patients with vitamin D insufficiency (≤20 ng/mL) had a higher incidence of grade ≥3 chemotherapy-induced peripheral neuropathy than those with sufficient vitamin D (20.7% vs 14.2%; OR 1.57, 95% CI 1.14–2.15, P=.005). The association held after adjusting for age and paclitaxel schedule (adjusted OR 1.65, P=.003). The authors concluded that pretreatment vitamin D insufficiency is the first validated potentially modifiable predictive biomarker of CIPN from paclitaxel.
A 2024 study in Frontiers in Medicine of 129 cancer patients on adjuvant paclitaxel reinforced the finding and added a mechanistic clue relevant to your glutathione research: there was a significant decrease in GSH levels in the serum of patients after paclitaxel chemotherapy, with a more pronounced decline in the vitamin D-deficient group, suggesting vitamin D may protect against paclitaxel's oxidative stress.
A few additional points worth noting for your wiki:
- Mechanism plausible. A mouse study reported that vitamin D deficiency induces mechanical hypersensitivity through microglial activation in the brain and spinal cord, similar to the effects of paclitaxel, and in mouse experiments, a vitamin D-deficient diet caused mechanical hypersensitivity and sensitized mice to paclitaxel.
- Racial disparity angle. Black patients had more prevalent vitamin D insufficiency (77.8% vs 28.6% in white patients) and increased PN risk (29.3% vs 13.5%); adjusting for vitamin D insufficiency decreased but did not eliminate the higher PN risk in Black patients — directly relevant to your health-equity work.
- Earlier signal. A 2020 Breast Cancer Res Treat paper (Jennaro et al.) had already reported that vitamin D deficiency increases severity of paclitaxel-induced peripheral neuropathy; the 2023 SWOG analysis was the validation.
- Caveat. These are observational/prospective-retrospective findings. Prospective trials are needed to determine whether vitamin D supplementation prevents CIPN and improves treatment outcomes — no RCT of supplementation-before-paclitaxel has reported yet.
Bottom line: the association is real and now validated in a phase III cohort, and there's a credible mechanism (microglial activation + glutathione depletion). The remaining gap is an interventional trial showing that correcting deficiency before chemotherapy actually prevents the neuropathy.