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For many breast cancer patients, surgery ends one ordeal and begins another. The tumor may be gone, after a mastectomy, the body is left with fresh wounds, swelling, and pain. A breath, a shift in bed, even a small reach can suddenly feel complicated.
A new study suggests that a simple blood test before surgery could help identify who may struggle more.
Researchers at Fayoum University Hospital in Egypt followed 184 women undergoing unilateral modified radical mastectomy, a surgery to remove one breast and nearby lymph nodes. Women with vitamin D deficiency before surgery were more likely to report moderate pain afterward and needed substantially more opioid medication during recovery.
Why Vitamin D?
Vitamin D is best known for helping the body absorb calcium, which is why doctors often bring it up when discussing bones. But that’s only part of the story.
Vitamin D also interacts with the immune system and inflammation, both of which shape how the body responds to injury. Because surgery is, in a controlled sense, a major injury, researchers have been asking whether low vitamin D levels might make patients more sensitive to pain afterward.
To test that idea in breast cancer surgery, the Fayoum University team measured each patient’s blood level of 25-hydroxyvitamin D, the standard marker used to assess vitamin D status. They then compared women whose levels were below 30 nmol/L, the study’s cutoff for deficiency, with women at or above that threshold. The study included 92 women in each group.
The comparison was designed to be as clean as possible. The two groups were similar in age, body mass index, preoperative pain, physical status, and surgery duration. All patients received the same pain-control approach: fentanyl during surgery, intravenous paracetamol, also known as acetaminophen, after surgery, and patient-controlled tramadol for breakthrough pain.
The Pain Scores
Image adapted from the study by ZME Science.
Immediately after surgery, both groups reported low pain scores. By six hours, the difference had started to emerge: 32.6% of vitamin D-deficient patients had moderate to severe pain, compared with 19.6% of those with sufficient vitamin D.
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By 12 hours (the study’s main checkpoint) the gap was even larger. Moderate to severe pain appeared in 17.4% of deficient patients, compared with just 2.2% of sufficient patients. Importantly, no patient in either group reported severe pain of 7 or higher on the standard 0-to-10 pain scale. The difference came from moderate pain. That may sound less dramatic, but moderate pain can still make the first day after surgery harder, especially when a patient is trying to breathe deeply, move safely, or begin recovery.
Across the first 24 hours, vitamin D deficiency was linked to more than triple the odds of moderate to severe pain after researchers adjusted for age, body mass index, physical status, surgery duration, and fentanyl use.
The opioid difference was striking. During surgery, women with low vitamin D received about 8 micrograms more fentanyl on average, a modest increase. After surgery, they used about 112 milligrams more tramadol than women with sufficient vitamin D.
That extra medication may have brought consequences. Nausea occurred more often in the deficient group. Vomiting appeared only in that group, though the number of cases was too small to prove a reliable difference. No patient had respiratory depression.
The researchers also found a slightly longer hospital stay among vitamin D-deficient patients, but the difference was tiny—about 1.05 days versus 1 day—so its practical meaning remains uncertain.
What Doctors Can Take From This
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The finding is promising, but it is not proof.
The study followed patients as they were, rather than randomly assigning some to receive vitamin D before surgery. That means low vitamin D may be a marker for some other factor that raises pain risk. The study also came from a single hospital, followed patients for only 24 hours and did not account for anxiety, depression, sleep problems, cancer stage, or earlier cancer treatment.
Still, the results give doctors a practical question to test. Vitamin D deficiency is easy to screen for, and it can often be corrected. If future trials show that supplementation lowers pain or reduces opioid use, a cheap blood test before mastectomy could help identify patients who need extra attention before the first incision.
For patients, the message is more cautious. The study does not mean that vitamin D pills will make surgery painless, or that anyone should start high-dose supplements on their own before an operation. But it does suggest that vitamin D status may belong in the broader conversation about preparing the body for cancer surgery—and perhaps other operations where postoperative pain is a major concern.
The study was published in the journal Regional Anesthesia & Pain Medicine.