Molecular Imaging Insight - May 2008 - (Page 5) cer Network; the organization publishes guidelines to help inform decision-making in the management of all types of cancer. Changing patient management, changing outcomes Clinical research shows PET can change management and outcomes in breast cancer. Over the last five years, numerous studies have shown that PET changes management in up to 40 percent of breast cancer cases. In some cases, PET may provide the data needed to shift radiation fields. In others, it may show that a patient is not responding to a specific therapy, and an alterative can be offered. “FDG-PET is most likely to impact the management and treatment of breast cancer when the referring oncologist asks specific questions,” explains Mankoff. For example, when an oncologist orders a PET study to determine if the extent of disease is locoregional or more widespread, PET may have a significant impact upon the choice of therapy. tively favorable with CMS paying fairly broadly for staging and re-staging of breast cancer as well as monitoring therapeutic response. There are exceptions to CMS’ reimbursement policy. Axillary node staging of early breast cancer, for example, is not covered; however, data have not yet shown that PET provides useful information when used to stage these cases. On the regulation side, breast cancer is an area where PET and molecular imaging can play a significant role; it will be important for regulatory approaches to be tailored to molecular imaging applications. Mankoff explains, “Regulatory agencies need to streamline the path to clinical use for diagnostic agents. They should not be treated in the same was as therapeutic agents. Tracers differ from therapeutic agents in a number of ways. Phy- Emerging applications PET has demonstrated its merit in many breast cancer applications, but the technology could be used more widely in several ways. For instance, the emergence of new treatments for breast cancer presents new opportunities. In addition, new radiotracers also could boost the utility of PET in breast cancer. Finally, positron emission mammography (PEM), a new PET technology, could improve early-stage imaging In the past, oncologists were fairly limited in their treatment choices for patients with breast cancer. The last few years, however, have seen the addition of a number of new therapeutic options. “With more treatment options, oncologists need to know very quickly if they have selected the right one because the patient can be switched to an alternative that may be more effective,” says Mankoff. Measuring early response to therapy is the domain of PET imaging. The second emerging arena is radio-tracer development. Several new tracers under development could deliver additional improvements in PET imaging for breast cancer. For example, proliferation tracers such as 18F-fluorothymidine (FLT) can be used to evaluate cell proliferation to provide additional information about early therapeutic response. Early research indicates that FLT may indicate response to treatment even earlier than FDG. FES, a labeled estrogen, can be used for estrogen-receptor imaging to predict which cancers will respond to or resist hormonal therapy. In addition, FES could be deployed to assess the effectiveness of treatments that target estrogen. PEM, a dedicated imaging device for the breast, is designed for positron imaging in the breast and offers the potential for higher spatial resolution and the ability to quantify tracer uptake in small breast lesions. In the future, PEM may be used in early staging of breast cancer and to help direct early breast cancer treatment using FDG or other tracers. PET•CT study shows large primary tumor with axillary lymph node metastases. Biograph 16 PET•CT images courtesy of Bejing Hospital, Beijing, China. sicians do not give patients diagnostic agents over and over again, and the diagnostic agents do not have any pharmacological effects. I suspect the regulatory issues associated with new imaging probes will be faced first in the PET arena, as new PET tracers are farther along in the development process than other molecular imaging modality agents.” The Society of Nuclear Medicine (SNM) and other molecular imaging organizations aim to resolve the issue by educating regulatory bodies about the nuances of diagnostic agents used in molecular imaging studies. PET delivers PET continues to prove its utility in breast cancer. For years, molecular imaging’s premiere modality has shown that it can accurately stage advanced and locally advanced breast cancer. Increasingly, medical oncologists turn to PET as the imaging tool to monitor therapeutic response and to direct therapy. In the rapidly evolving world of breast cancer treatment, PET provides a means to gather the clinically useful data needed to inform treatment options. PET is still in its early stages of utilization. New developments in the form of new tracers will further enhance the utility of PET to the benefit of breast cancer patients. May 2008 | Molecular Imaging Insight The big picture: reimbursement and regulation CMS approved breast cancer staging as one of the first indications for PET scanning five years ago, and reimbursement remains relaMolecularImaging.net http://MolecularImaging.net
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