Transforming growth factor beta (TGF-β) exhibits complex and context-dependent cellular responses. While it mostly induces tumor-suppressive effects in early stages of tumorigenesis, tumor-promoting properties are evident in advanced disease. This TGF-β duality is still not fully understood, and whether TGF-β supports invasion and metastasis by influencing cancer cells directly, or rather through the stromal tumor compartment, remains a matter of debate. Here, we utilized a library of colorectal cancer (CRC) patient-derived tumoroids (PDTs), representing a spectrum of tumor stages, to study cancer cell-specific responses to TGF-β. Using conditions allowing for the differentiation of PDTs, we observed TGF-β-induced tumor-suppressive effects in early-stage tumoroids, whereas more advanced tumoroids were less sensitive to the treatment. Notably, one tumoroid line harboring an atypical KRAS