Vitamin D Deficiency is Associated with the Severity of Radiation-Induced Proctitis in Cancer Patients
Radiation Oncology, Received: December 27, 2014; Feb 11, 2015, DOI: http://dx.doi.org/10.1016/j.ijrobp.2015.02.011
Amir Ghorbanzadeh Moghaddam, MDemail, Ali Gholamrezaei, MD, Simin Hemati, MD, Associate Prof. Radiation Oncology
Radiation-induced injury to the normal tissues is a common complication of radiotherapy in cancer patients. Considering the role of vitamin D in mucosal barrier hemostasis and inflammatory responses, we investigated whether vitamin D deficiency is associated with the severity of radiation-induced acute proctitis in cancer patients.
Methods and Materials
This prospective observational study was conducted on cancer patients referred for pelvic radiotherapy. Serum concentration of 25-hydroxyvitamin D was measured before radiotherapy. Vitamin D deficiency was defined as 25-hydroxyvitamin D concentrations of <35 nmol/L and <40 nmol/L in males and females patients, respectively, based on available normative data. Acute proctitis was assessed after five weeks of radiotherapy (total received radiation dose of 50 Grays) and graded from 0 to 4 using the Radiation Therapy Oncology Group (RTOG) classification.
Ninety eight patients with mean age of 62.8 ± 9.1 years (57.1% male) were studied. Vitamin D deficiency was found in 57 (58.1%) patients. Symptoms of acute proctitis were occurred in 72 (73.4%) patients after radiotherapy. The RTOG grade was significantly higher in patients with vitamin D deficiency than normal cases (median [interquartile range] of 2 [0. 5 to 3] vs. 1 [0 to 2], P=0.037).
Vitamin D deficiency was associated with RTOG grade of ≥2 independently from possible confounding factors; odds ratio [95% confidence interval] = 3.07 [1.27 to 7.50], P=0.013.
Vitamin D deficiency is associated with increased severity of radiation-induced acute proctitis. Investigating the underlying mechanisms of this association and evaluating the effectiveness of vitamin D therapy in preventing radiation-induced acute proctitis is warranted.