Low Vitamin D Linked to More Pain After Breast Cancer Surgery, Study Finds

Low vitamin D levels may make recovery from breast cancer surgery more painful and raise the need for opioid painkillers, a study in the journal Regional Anesthesia & Pain Medicine reports. Patients with vitamin D deficiency, below 30 nmol/L, could benefit from supplementation before a radical mastectomy, a major operation removing an entire breast, the findings suggest.

Vitamin D is known mainly for bone health, but growing evidence suggests it also influences how the body senses pain, possibly via inflammation and immune effects. Since vitamin D deficiency is common among breast cancer patients, researchers at Fayoum University Hospital, Egypt, tested the link with a prospective observational study, following patients over time without assigning treatments, from September 2024 to April 2025.

The study enrolled 184 patients scheduled for a unilateral radical mastectomy. Half were vitamin D deficient, below 30 nmol/L, half sufficient, above it; average age was 44 versus 42. All got standard care, and staff did not know patients' vitamin D status. Surgery included the opioid fentanyl; afterward everyone received intravenous paracetamol every 8 hours and could self-administer the opioid tramadol via a patient-controlled pump.

Deficient patients were three times more likely to report moderate to severe pain in the first 24 hours than sufficient patients, though none reported severe pain, 7 or higher on a 0-10 scale; the gap came entirely from moderate pain. The deficient group needed 8 more micrograms of fentanyl during surgery, a modest difference, and 112mg more tramadol afterward. Nausea was more common among deficient patients, and vomiting occurred only in that group, though not significantly.

Researchers cautioned this single-center, observational study cannot prove vitamin D deficiency caused the extra pain. They did not measure inflammatory markers, and lacked data on anxiety, depression, cancer stage or presurgery sleep that could also affect pain. They concluded vitamin D deficiency "is associated with a higher occurrence of moderate to severe postoperative pain and increased opioid consumption."