Breast cancer patients with vitamin D deficiency may benefit from taking supplements before operations.
Vitamin D deficiency is associated with more moderate to severe pain following breast cancer surgery and an increased consumption of opioid drugs.
This is according to research published in the journal Regional Anaesthesia & Pain Medicine.
Breast cancer patients with low levels of vitamin D (below 30 nmol/L) may therefore benefit from taking supplements before undergoing a radical mastectomy, the researchers suggest.
The prospective observational study, carried out at Fayoum University Hospital in Egypt between September 2024 and April 2025, included 184 breast cancer patients who were scheduled to undergo surgical removal of one entire breast.
Half of the patients were classified as vitamin D deficient (below 30 nmol/L) and half were vitamin D sufficient (above 30 nmol/L).
Both groups had similar characteristics, with an average age of 44 in the vitamin D-deficient group and 42 in the vitamin D-sufficient group.
Patients were managed according to the hospital’s routine protocol both during and after surgery. Clinical staff involved in their care were unaware of the patients’ vitamin D levels.
The opioid fentanyl was administered during the operation to manage acute pain.
Following surgery, all patients were given paracetamol through a drip every eight hours. In addition, patients could control how much tramadol (another opioid analgesic) they were given by directly pressing a button.
Patients with vitamin D deficiency were three times more likely to report moderate to severe postoperative pain at any time point during the first 24 hours than those with sufficient vitamin D levels, the study found.
The researchers noted, however, that no patient in either group reported severe pain (7 or over on a scale of 0 to 10), so the difference was due entirely to a reduction in moderate pain (4-6 on the pain scale).
Vitamin D-deficient patients received, on average, 8 μg more fentanyl during surgery, which the researchers described as a modest difference.
However, the study found that those in the vitamin D-deficient group used substantially more tramadol (112mg) after surgery than those who had sufficient vitamin D levels.
Postoperative nausea was more common in the vitamin D-deficient group, and vomiting occurred only in that group, although the difference in vomiting was small and not statistically significant.
The study had some limitations. It was observational and conducted at a single centre, so no firm conclusion can be drawn about cause and effect. The researchers also did not assess inflammatory markers, so they could not explore the mechanisms underlying the relationship between vitamin D and pain.
Nevertheless, the researchers conclude that ‘vitamin D deficiency is associated with a higher occurrence of moderate to severe postoperative pain and increased opioid consumption in patients undergoing unilateral modified radical mastectomy’.
They suggest: ‘Preoperative vitamin D supplementation in breast cancer patients with vitamin D levels below 30 nmol/L may have a role in modulating postoperative pain.’
