MMP9 and aneurysm: Papalambros et al23 found that the concentration of MMP-9 in the arterial wall correlates positively with aneurysm size and radiotherapy has been shown to increase the expression of MMP-9.24 Wilson et al25 found that the concentration of MMP-8 is increased at the site of abdominal aortic aneurysm rupture, and radiotherapy also enhances the expression of MMP-8, which modulates the pharmacokinetics of anticancer drugs.26