Are women who have had breast cancer more likely to develop deep vein thrombosis?

Maybe: Early stage breast cancer is associated with a very minimal risk of DVT although some of the treatments (estrogen blockage) may increase that risk as does smoking. Advanced stages of most cancers are associated with increased dvt.

DVT: Active cancer increases the risk of dvt.

DVT risk: Active cancer increases risk for DVT significantly. tamoxifen can increase risk for DVT and PE. See this link for guidance. http://www.ncbi.nlm.nih.gov/pubmed/19569248