Vitamin D is a steroid-like hormone which acts by binding to vitamin D receptor (VDR). It plays a main role in the calcium homeostasis and metabolism. In addition, vitamin D display other important effects called “non-classical actions.” Among them, vitamin D regulates immune cells function and hematopoietic cells differentiation and proliferation. Based on these effects, it is currently being evaluated for the treatment of hematologic malignancies. In addition, vitamin D levels have been correlated with patients’ outcome after allogeneic stem cell transplantation, where it might regulate immune response and, accordingly, might influence the risk of graft-versus-host disease. Here, we present recent advances regarding its clinical applications both in the treatment of hematologic malignancies and in the transplant setting.

The use of PET in patients with marginal zone B cell lymphoma (MZL) is controversial because of variability of fluorodeoxyglucose (FDG) avidity. We analyzed 40 PET/CT in 25 consecutive patients to compare its performance with CT at staging and as a first-line response assessment. Sensitivity of PET/CT and CT was 96 and 76%. Mean standard uptake value was 6.1, 6.9 and 3.4 (p = 0.3) in nodal, extranodal and splenic subtypes, respectively. Of 17 patients (extranodal: n = 9; nodal: n = 6; splenic subtype: n = 2) with both imaging tests available at diagnosis, 8 (47%) had more involved areas with PET/CT than with CT, 75% of which were extranodal lesions. PET/CT resulted in upstaging of five patients although treatment of only two of them was changed. Responses of 15 patients with post-treatment PET/CT were the following: 9 negative and 6 positive of which 3 were isolated residual lesions. Progression was documented in two of these three patients. Response was also assessed by CT in 11 patients. Discrepancies were found in three: Two were in complete remission by CT while PET/CT detected localized residual disease; another patient was in partial remission by CT, whereas PET/CT showed only one positive lesion. Two of these three patients relapsed. Patients with negative post-treatment PET/CT did not relapse. With a median follow-up of 50 months (10-152 months), 3-year overall survival was 100 and 80% for patients with negative and positive post-treatment PET/CT (p = 0.2). Three-year disease-free survival was 86%; the negative predictive value (NPV) was 100%, and the positive predictive value (PPV) was 83.3%. Although a larger number of patients will be required to further confirm these data, we can conclude that PET/CT is a useful imaging tool for both staging and response assessment in patients with nodal and extranodal MZL as a result of its high sensitivity, NPV and PPV.