Purpose : Limited data exist about clinically relevant bleeding events related to antiplatelet therapy after percutaneous coronary intervention (PCI) in cancer patients. We investigated the risk factors for clinically relevant bleeding events in patients with cancer after PCI with stent implantation. Patients and Methods : Patients with solid cancer subjected to first PCI were divided into active (n = 45) and non-active cancer groups (n = 44). The active group included non-operable patients on treatment or with metastasis ; the non-active included those already subjected to or for whom radical surgery was planned within 3 months after the index PCI. Results : During a median follow-up of 2.2 years, 11 bleeding events occurred, with only one occurring in the non-active cancer group. Half of them occurred during the dual-antiplatelet therapy (DAPT) period, and the rest occurred during single-antiplatelet therapy (SAPT) period. Kaplan-Meier analysis showed significantly more bleeding events in the active cancer group (p = 0.010). Multivariate Cox regression hazard analysis revealed cancer activity as a significant independent risk factor for bleeding (p = 0.023) ; but not for three-point major adverse cardiovascular events. Conclusion : Clinically relevant bleeding risk after PCI was significantly lower in non-active cancer. Active cancer group had clinically relevant bleeding during both DAPT and SAPT periods