Study Links Low Vitamin D Levels to Increased Postoperative Pain in Breast Cancer Patients

Vitamin D is primarily known for its role in maintaining bone health. However, accumulating evidence suggests it may also affect how the body processes and senses pain, potentially linked to its impact on inflammation and the immune system.

The study was conducted at Fayoum University Hospital in Egypt between September 2024 and April 2025. It included 184 breast cancer patients scheduled for radical mastectomy. Half of the participants were determined to be vitamin D deficient, while the other half had sufficient levels. The average age was 44 for those deficient in vitamin D and 42 for those with sufficient levels.

All patients received standard treatment during and after surgery, and clinical staff were unaware of the patients' vitamin D statuses, minimizing bias in pain management. During surgery, patients received fentanyl, a potent opioid for acute pain management, along with intravenous paracetamol post-surgery. They also had the option to self-administer tramadol through a patient-controlled pain relief system.

Results showed that patients with vitamin D deficiency were three times more likely to report moderate to severe pain within the first 24 hours post-surgery compared to those with sufficient vitamin D levels. The difference was significant in terms of moderate pain, although no patients experienced severe pain (rated 7 or above on a scale of 0 to 10).

In terms of medication, those with vitamin D deficiency required an average of 8 μg more fentanyl during surgery and used significantly more tramadol (112 mg) after surgery compared to those with sufficient vitamin D levels. Increased opioid consumption is noteworthy due to the associated risks of side effects and potential dependency.

Postoperative nausea was more prevalent in patients with low vitamin D, while vomiting occurred only in that group, though this difference was not statistically significant.

The researchers caution that the observational nature of the study does not establish a direct cause-and-effect relationship between vitamin D deficiency and increased pain or opioid use. Limitations include a lack of measurement of inflammatory markers and the absence of data on several factors that could affect pain post-surgery, such as anxiety and depression.

They conclude that there is a notable association between vitamin D deficiency and higher levels of postoperative pain and opioid use, suggesting that preoperative vitamin D supplementation may help manage pain in breast cancer patients with low vitamin D levels.