Furthermore, the percentage decrease in serum let-7a levels after 60 Gy radiotherapy was inversely correlated with tumor regression, as measured by changes in the longest tumor diameter 2 months after radiotherapy (Fig. 6E), whereas the percentage increase in serum IL-6 levels after 60 Gy radiotherapy was inversely correlated with tumor regression (Fig. 6F). Here, IL6 is linked to neoplasm.