Cancer can spread by both lymphatic and hematogenous routes, and metastases are found most commonly in organs fed by the downstream lymphatic and blood flow.1 The tumor cells secrete proteinases or induce proteinase secretion by stromal cells that lead to degradation of the architecture of vascular basal membranes, creating local access through which to migrate into vasculature. In patients with long-standing diabetes mellitus, diabetic microangiopathy renders the vascular basal membrane less digestible by tumor cells, which may play a role in impeding neoplastic cell spread and metastasis.2,3 There has been debate in the literature concerning the protective effect of diabetes on patients with cancer in terms of improving their mortality. In reference to the 2 letters published in the ARCHIVES,4,5 we undertook a larger database review to investigate the possible hypothesis that diabetes has a protective effect in patients with coexisting cancers.
Hanbali A, Al-Khasawneh K, Cole-Johnson C, Divine G, Ali H. Protective Effect of Diabetes Against Metastasis in Patients With Non–Small Cell Lung Cancer. Arch Intern Med. 2007;167(5):513. doi:10.1001/archinte.167.5.513-a