TGFB1 and breast cancer: Interestingly, TGF-β1 levels are often elevated in cancer patients, even before radiation, likely due to the malignancy itself.39,40 Reducing active TGF-β1 levels may not only help reduce soft tissue complication but also tumor progression and metastasis.41 Fibroblasts, or cancer-associated fibroblasts, are known to play a role in promotion of cancer, including breast cancer.