Vitamin D deficiency is associated with more moderate to severe pain following breast cancer surgery and an increased consumption of opioid drugs, finds research published online in the journal Regional Anesthesia & Pain Medicine.
Breast cancer patients with low levels of vitamin D (below 30 nmol/L) may benefit from taking supplements before undergoing a radical mastectomy, suggest researchers.
There is emerging evidence suggesting that vitamin D helps control how pain is felt and processed by the body. This is likely due to its anti-inflammatory effects and action on the immune system.
Vitamin D deficiency is also commonly reported among patients with breast cancer.
A team of researchers set out to examine the relationship between vitamin D deficiency and postoperative pain in patients undergoing breast cancer surgery.
Their 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 classified as 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 8 hours. In addition, patients could control how much tramadol (another opioid analgesic) they were given by directly pressing a button.
Patients reported their pain levels at zero, 6 hours, 12 hours, 18 hours and 24 hours after surgery. Nausea and vomiting, sedation score and days in hospital following surgery were also recorded.
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 those in the vitamin D deficient group used substantially more tramadol (112mg) after surgery than those who had sufficient vitamin D levels. This strong opioid was controlled directly by the patient up to a maximum dose of 50mg per hour.
Opioid drugs can cause a number of side effects including nausea, vomiting, drowsiness and confusion, while also carrying risks of dependency and addiction.
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 could not explore the mechanisms underlying the relationship between vitamin D and pain. Data was also not collected on anxiety, depression, cancer stage, treatment or sleep disturbance before the surgery was carried out.
Nevertheless, the researchers conclude, "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."
