Paclitaxel (Chemo) neuropathy fell from 80% to 67% when vitamin D was recommended

Clin J Oncol Nurs. 2026 Oct;30(5):375-379. doi: 10.1188/26.CJON.375-379

Singh RJ, Schneider SM, Thompson JA, Khan A, Affronti ML

Dose and response not reported. The public portion gives neither the vitamin D dose nor the achieved 25(OH)D level, and it doesn't define the cutoff for "insufficiency." The rest is paywalled.
Probably a low dose. The cited target is only 20–30 ng/mL, and the intervention was recommending supplementation. That suggests an over-the-counter dose of about 1,000–2,000 IU/day with no loading dose.
No time to raise levels. Neuropathy from weekly paclitaxel usually begins within the first few weeks. Without a loading dose, 1,000–2,000 IU/day raises 25(OH)D only a few ng/mL in that time.
The strongest signal is one sentence in the abstract. All 11 patients with vitamin D insufficiency developed CIPN. If those 11 were in the post-implementation group, only 7 of the other 16 (44%) did: 100% vs 44%.
The headline result is weak. 16/20 vs 18/27 gives a Fisher exact p ≈ 0.35. The "13% reduction" is 13 percentage points, about 17% relative. The sample is tiny and the comparison group is historical.
Consistent with larger studies. In SWOG S0221 (1,191 women), grade ≥3 CIPN occurred in 20.7% of women with 25(OH)D ≤20 ng/mL vs 14.2% of the rest (OR 1.57) [SWOG S0221]. Lixian 2024, cited by the authors, found OR 6.2 for CIPN with deficiency.
* Other trials using real loading doses:*
- [NCT06596122]: 50,000 IU/week for 8 weeks, then 100,000 IU/month during chemotherapy.
- [NCT05852496]: 6,000 IU/day or 50,000 IU/week for 8 weeks, then 3,000–6,000 IU/day.

Any grade: about 70–80% [[CJON](https://www.ons.org/publications-research/cjon/30/5/correcting-vitamin-d-deficiency-prevent-paclitaxel-induced-peripheral-neuropathy-practice-change)] [Zhang 2024]
Grade ≥3: about 16% [SWOG S0221]
Needing paclitaxel reduced or interrupted: about 25% [Chen BCRT]
Still present 6+ months after chemotherapy (all neurotoxic drugs): about 30% [Seretny 2014]

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