Vitamin D Deficiency May Increase Pain After Breast Cancer Surgery

Before a breast cancer patient undergoes surgery, her clinical team completes an extensive checklist. They assess heart function, blood count and medicine allergies, but vitamin D is not usually included, despite the possibility that deficiency could worsen pain during recovery.

At a hospital in Egypt, researchers set out to examine the implications of that omission. They monitored breast cancer patients undergoing mastectomy and throughout the challenging 24 hours afterwards, focusing on a factor that most surgical protocols do not measure.

A common vitamin D deficiency

Mahdy Ahmed Abdelhady, M.D., Ph.D., of Fayoum University in Egypt, led a team investigating whether one blood marker could forecast the amount of pain a patient would experience after surgery. They selected a procedure associated with a demanding recovery.

Vitamin D deficiency is more prevalent among women with breast cancer than in the wider population. Clinicians had long noted that connection, but no one had established what effect, if any, it had on treatment results.

Of the 184 patients, half had vitamin D concentrations below the deficiency threshold, while the remainder were above it. The groups were comparable for other factors, including age, surgical plan and underlying health, and both had average ages in the low 40s.

Monitoring pain hour by hour

The research took place at the university hospital between September 2024 and April 2025. All participants were due to have a mastectomy - the operation to remove an entire breast - a major procedure followed by a gradual recovery.

The doctors and nurses caring for the patients were unaware of their group allocation. Each patient received an identical pain-control regimen: fentanyl, an opioid analgesic, during surgery, followed by intravenous acetaminophen at set intervals afterwards.

Patients could administer extra pain relief themselves using a button-controlled pump that delivered tramadol, an opioid. Nurses documented pain on a 0-to-10 scale immediately after surgery and at four intervals during the following 24 hours.

Three times more postoperative pain

The main outcome was postoperative pain at 12 hours, defined as a score above 3 on the standard scale. Those in the deficient group were around three times as likely as patients with adequate levels to record pain in this range.

No women in either group described severe pain, defined as 7 or higher on the scale. The difference was wholly within the moderate range of 4 to 6, at which patients experience enough discomfort to seek further relief.

This distinction makes the result more precise. Vitamin D-deficient patients were not experiencing emergency-level pain; rather, they had the persistent discomfort associated with moderate scores - the sort that leads a recovering patient to use the button every few hours.

Opioids make up the difference

Opioid consumption revealed the most pronounced split. During the procedure, patients with deficiency required only approximately 8 micrograms more fentanyl than the other group - a small increase that the researchers did not regard as clinically meaningful by itself.

The disparity became much larger after surgery. Over the first day, patients with low vitamin D used the button frequently enough to receive an average of 112 milligrams more tramadol than those whose levels were sufficient.

Nausea was also associated with deficiency. A greater number of patients in the low-vitamin group reported it during recovery, in keeping with their greater opioid exposure. Vomiting occurred only in this group, although the number of cases was too low to be statistically significant.

Vitamin D and breast cancer surgery pain

Before this research, studies had suggested that vitamin D has functions beyond bone health. Previous work involving chronic back pain and recovery after gallbladder surgery associated low levels with higher pain scores - not uniformly, but with a recurring pattern.

The proposed process involves inflammation. Vitamin D is believed to reduce chemical signals that heighten sensitivity in injured tissue, and a recent paper linked this effect to its influence on immune cells and molecules that intensify pain.

Postoperative pain following breast cancer surgery can now be added to this developing body of evidence. Before this study, the association had not been measured in this particular patient group, in which vitamin D deficiency is already common before diagnosis.

Study limitations

Abdelhady’s team clearly acknowledges the limits of its design. Even a carefully conducted observational study cannot demonstrate that deficiency itself caused a more difficult recovery; it can only show that both factors occur together in this patient group.

The analysis also excluded several variables. Mental health, cancer stage, previous treatments and sleep quality can all influence the way the body perceives pain. The researchers gathered no data on these factors, and any could account for part of the observed difference.

The researchers did not take blood samples to assess inflammation levels. Consequently, the suggested mechanism is a plausible hypothesis rather than one directly verified by the results. Establishing it will need a different study design.

What may change

Despite these limitations, the practical issue for clinicians concerns a straightforward intervention. A vitamin D blood test is inexpensive, quick and already widely used. When supplementation is required, it is among the simplest treatments in medicine.

Should a clinical trial of preoperative supplementation in deficient patients validate the association, breast cancer surgery centres could make the test part of standard preparation. Patients entering the operating theatre with corrected levels could experience less pain and require fewer opioids afterwards.

This research identifies a distinct pattern: low vitamin D before breast cancer surgery is associated with greater pain and higher opioid use afterwards. The next study is not a matter of whether it should be conducted, but how soon it can be.