Why Some Cancers Spread to Bones

Researchers at the University of Michigan (U-M) School of Dentistry have found that administering a common che­motherapy drug before bone tumors took root actually fertilized the bone marrow, en­abling cancer cells, once introduced, to seed and grow more easily. The findings provide valuable insight as to why some cancers me­tas­tasize to bone and could eventually result in new metastasis-prevention drugs, said Dr. Laurie McCauley, professor in the de­partment of periodontics and oral med­icine and principal in­ves­tigator on the study. The good news is that re­search­ers reversed the tum­or-friend­ly effect of the drug, called cy­clophosphamide, by in­hib­iting another cell-communicating protein in the bone marrow, called CCL2. “This work is early and still at the preclinical level,” said Dr. McCauley, who also has an appointment in the de­part­ment of Pathology at the U-M Health System. “How­ever, the biggest potential impact is in metastasis preventive strategies. If we better understood the specific mediators, or conditions, in the bone marrow that support tumors, we could develop more effective therapeutics to prevent local cancers from spreading and hence re­duce metastasis to the bone.”

The study highlights the potential for the bone marrow to provide the right environment for tumors to me­tastasize. Many cancers, such as breast and prostate, are likely to spread, or metastasize, to bones. While effective at attack­ing tumor cells, a side effect of cyclophosphamide (and many other chemotherapy drugs) is that it suppresses certain bone marrow cells that help the immune system and increases some harmful cells. Re­searchers hypothesized correctly that the drug would make the bone marrow more tumor-friendly. The paper, “Cy­clophosphamide Creates a Receptive Micro­environ­ment for Prostate Cancer Skeletal Me­tastasis,” appears in the jour­­nal Cancer Re­search.

(Source: U-M School of Den­tistry, May 15, 2012)