Influence of Preoperative Vitamin D Level on Postoperative Pain in Breast Cancer Surgery Patients

Vitamin D deficiency is a general problem that vigorously affects human health . Breast cancer is the most frequently diagnosed life-threatening cancer in women and the leading cause of cancer death among women.Vitamin D deficiency is common in breast cancer patients and some evidence suggests that low vitamin D status enhances the risk for disease development or progression .

Though the relationship between vitamin D and breast cancer is unclear . Several research studies currently support vitamin D deficiency as a risk factor for breast cancer. Observational studies have also revealed significant relationships of vitamin D with breast cancer, colorectal cancer, prostate cancer and pancreatic cancer 10'11'12'13'14. However, no work has been done to investigate the relationship between vitamin D deficiency and acute postoperative pain in breast cancer surgery patients. In the current study we will investigate the relationship between preoperative vitamin D levels and acute postoperative pain in cancer breast surgery patients.

The aim of current study is to investigate the relationship between preoperative vitamin D levels and acute postoperative pain in breast cancer surgery patients.

This study will be performed in the FAYOUM University Hospital after the local Institutional Ethics Committee and local institutional review board approval. Newly diagnosed and pathologically proven breast cancer patients who are prepared for elective breast cancer surgery will be recruited from the general surgery department of our hospital. The study design will be prospective observational study. A detailed informed consent will be signed by the eligible patients before recruitment.

Measurement of vitamin D:

The characteristics of 25 (OH) D3 are relatively longer half-life than 1.25 (OH)2 D3, stability, strong detection repeatability, and no biological activity. Generally, systemic levels of the more stable 25 (OH) D3 are considered to be the best index to reflect status of vitamin D in the individual patient .

study design:

Serum 25(OH)D levels will be measured preoperative . Patients will be divided into two groups :

(1) group D: vitamin D-deficient group (\<30nmol/L); and (2) group S: vitamin D-sufficient group (≥30nmol/L) .

Randomization:

Preoperative serum 25(OH) D levels will be assessed by an anaesthesiologist who will not be included in the study, to get the number of patients required in each group. Randomization will be done via computer-generated random numbers that will be placed in separate closed envelopes and will be opened by study investigators just after induction of general anaesthesia. Neither the patients, the study investigators, the attending clinicians nor the data collectors will be aware of the allocation of groups till the study ends. The patients will be allocated in 1:1 ratio to one of the two groups: group D: vitamin D-deficient group (n= 92 ), and group S: vitamin D-sufficient group (n= 92).

Anaesthesia procedure:

All patients will undergo routine preoperative investigations; CBC, coagulation profile, liver function tests, kidney function tests, ECG and preoperative serum 25(OH)D level. Upon arrival to the operating room, standard monitors (5-lead electrocardiogram, pulse oximeter, noninvasive blood pressure monitoring) will be applied and continue all over the operation. An IV access will be established. All patients will receive IV ondansetron 4 mg before induction of anesthesia as a premedication. General anesthesia will be performed as follows: induction using IV propofol (2mg/kg), atracurium (0.5mg/kg), and fentanyl (1 microgram/kg). A cuffed endotracheal tube (7mm ID) will be placed to secure the airway. Mechanical ventilation parameters will be adjusted to ensure proper oxygenation and ventilation with normocapnia. Maintenance of anesthesia will be made using inhalational anesthesia with isoflurane 1.5% volume concentration and IV atracurium (0.1 mg/kg) every 20 minutes. Continuous hemodynamic monitoring of blood pressure and heart rate will be done . If the systolic blood pressure decreased to a 20% below the baseline or less than 90 mmHg, 5 mg of ephedrine will be injected IV. Moreover, if the heart rate reduced to a 50 bpm or less, 0.5 mg of atropine will be injected IV. At the end of operation , the patients will be transferred to the postoperative anaesthesia care unit for routine monitoring and then to the general surgery department when they have a modified Aldrete score ≥9.

Postoperative Pain Management:

Throughout the first 24 hrs, patients will receive IV paracetamol 1 g every 8 hrs for postoperative analgesia according to the general surgery department protocol.

They also will receive IV tramadol through a patient controlled analgesia (PCA) system (concentration of 4 mg/mL); with; a 20 mg dose, a 10 mins lockout interval and a 50 mg 1 hr limit as supplementary analgesia with no background analgesia.

Eligibility Criteria:
Inclusion criteria:

* Female patients ASA II -III.
* aged 20-65 years, who will be scheduled to undergo elective unilateral breast cancer surgery.
* modified radical mastectomy.

Exclusion criteria:

* Patient refusal.
* Chronic opioid use.
* cognitive disorders.
* patients using drugs affecting the levels of calcium, phosphorus, and vitamin D, such as vitamin D supplement, calcitonin, and estrogen or its analogs, one month before enrolment.
* hyperparathyroidism or undergoing parathyroidectomy.
* diseases affecting vitamin D absorption, such as long-term diarrhea, chronic pancreatitis, biliary obstruction, colitis, partial resection of the small intestine.
* severe liver and kidney diseases.
* severe peripheral or central neuropathy.
* heart failure.
* pneumonia.
* parenteral nutrition patients.