Estimating the tumor-breast volume ratio from mammograms

Abstract

Each year, 182,000 women are diagnosed with breast cancer and 43,300 die, only in America. Currently, more than a million of new cases will be detected around the world. One woman in eight either has or will develop breast cancer in her lifetime. Mammograms are among the best early detection methods. Most women with breast cancer have some type of surgery: Lumpectomy removes only the breast lump and a surrounding margin of normal tissue. Partial or segmental mastectomy or quadrantectomy removes more breast tissue than a lumpectomy (up to one-quarter of the breast). In a total mastectomy the surgeon removes the entire breast, including the nipple. This operation is sometimes used to treat stage 0 breast cancers. For most women with stage I or II breast cancer, breast conservation therapy (lumpectomy and radiation therapy) is as effective as mastectomy. Survival rates of women treated with these 2 approaches are the same. However, breast conservation therapy is not an option for all women with breast cancer. One of the main factors to decide which type of surgery must be used (lumpectomy, quadrantectomy or total mastectomy) is the tumor-breast volume ratio. Unfortunately, because the mammograms are two-dimensional projections of the breast, a process to measure this relationship with the needed accuracy does not exist. So, a correct decision depends on the specialist's ability to imagine the 3D reconstruction from the mammograms. In order to assist the decision making of the surgeon, in this work we have implemented a software application which allows the surgeon to input the mammograms of the patient and obtain a 3D representation of the breast and the tumor. In summary, the software groups a set of tools to segment the breast and tumor from the input mammograms in an interactive way using the intelligent scissors technique, visualize the mammograms in 3D, reconstruct the 3D representation of the breast and tumor and compute a value which represents the volumetric ratio between the breast's reconstruction and the bounding volume of the tumor. This value can be used as a less subjective indicator to decide whether a lumpectomy or quadrantectomy is advisable.