The Role of Vitamin D in Predicting Response to Neoadjuvant Therapy in Patients With Rectal Cancer

It has been reported that better local control is achieved and sphincters are preserved at a higher rate with curative resections performed after neoadjuvant chemoradiotherapy in patients with locally advanced rectal cancers. In addition, it has been reported that local recurrence is reduced and survival is prolonged in patients with complete pathological response to neoadjuvant therapy. Therefore, the importance of predicting patients with pathological complete response has increased.

It has been reported that data obtained from PET-CT scans and clinical information such as tumor size, T stage, and N stage may be useful in predicting the response to neoadjuvant therapy in patients with locally advanced rectal cancer.

Consideration of blood biomarkers in predicting neoadjuvant response can be a very attractive option. Because samples are easily collected, relatively inexpensive to measure, and contain information about different aspects of tumor biology. There are a limited number of blood biomarkers such as CEA and IL-6 that have been studied in the literature.

Experimental studies show that vitamin D suppresses inflammation and protects against cancer by triggering differentiation. In 1980, Cedric and Frank Garland stated for the first time that vitamin D may affect the survival of the patient after the diagnosis of colorectal cancer. In later studies, a positive relationship was reported between the serum level of 25-hydroxyvitamin D - 25 (OH) D and survival rates for colorectal cancer, breast and prostate cancer. In addition, 25 (OH) D serum concentration has been shown to be inversely related to colorectal cancer progression.

In the light of all these information, the role of serum vitamin D levels before neoadjuvant treatment in predicting pathological response in patients with rectal cancer is investigated in this study.