Lani
09-25-2007, 12:24 PM
PET Also Useful for Cancer Prognosis
September 25, 2007 — The imaging technique typically used to identify the presence of disease may have an important future role in determining prognosis as well. Reporting in the September 4 Online First issue of Cancer, researchers show that positron emission tomography (PET) is useful in predicting treatment response and prognosis for patients with cervical cancer. Similar results have previously been observed in patients with head and neck cancer, esophagus, and lung cancer.
"The PET scan provides additional prognostic information that can enable clinicians to be more predictive in the preclinical stage," Elizabeth Kidd, MD, from the Department of Radiation Oncology at the Washington University School of Medicine in St. Louis, Missouri, told Medscape Oncology. "We are finding that PET can help doctors make treatment decisions for patients."
The researchers used PET with the glucose analog F-18 fluorodeoxyglucose (FDG), a widely available 3-D scanning technique. FDG is reportedly the most commonly used PET scan and measures how rapidly tumors take up a radiolabeled glucose tracer — high uptake results in a stronger or brighter signal in the scan.
The researchers found that the higher the standard uptake value (SUV) for FDG in the primary tumor, the greater the rate of recurrence and the lower the rate of survival of patients.
SUV Seems to Be More Predictive Than Current Staging Protocols
Patient-related and tumor-related factors such as age, histologic features, volume of the tumor, and stage have typically been critical attributes for predicting patient outcome and overall survival for cervical cancer. "In our study," the researchers write, "these attributes had a less significant association with prognosis and outcome than the primary tumor maximum SUV."
During an interview, Dr. Kidd admitted that her group was surprised by the results. "We had noticed previously that patients with higher SUV tended to have worse outcomes," she noted. "But we hadn't anticipated that SUV would be more predictive than standard staging protocols."
Dr. Kidd cautioned that the study is retrospective, and the findings therefore are limited, but she says that the potential implications of the work are promising.
The investigators looked at 287 patients with cervical cancer treated with surgery, chemotherapy, or radiation after standard treatment protocols. At the time of diagnosis, researchers obtained the SUV of the primary tumors. Cancers were staged in accordance with standard guidelines and relied largely on the size of the tumor and involvement with surrounding tissues. The cancers ranged from early stage IA2 to highly advanced stage IVB.
Patients were categorized in 3 different risk groups: low, medium, and high. Those with the lowest SUV had a survival rate of 95% at 5 years, those in the middle SUV range had a 70% 5-year survival rate, and those in the highest SUV range had a survival rate of 44% at 5 years.
Dr. Kidd explains that because a high SUV indicates that tumors take up glucose rapidly, the measurement may point to an important biological difference in these more aggressive cancers. "We're interested in finding out why this difference exists," she told Medscape Oncology. "We're hoping this will eventually lead to new methods for treating patients."
The researchers have disclosed no relevant financial relationships.
Cancer. Published online September 4, 200
September 25, 2007 — The imaging technique typically used to identify the presence of disease may have an important future role in determining prognosis as well. Reporting in the September 4 Online First issue of Cancer, researchers show that positron emission tomography (PET) is useful in predicting treatment response and prognosis for patients with cervical cancer. Similar results have previously been observed in patients with head and neck cancer, esophagus, and lung cancer.
"The PET scan provides additional prognostic information that can enable clinicians to be more predictive in the preclinical stage," Elizabeth Kidd, MD, from the Department of Radiation Oncology at the Washington University School of Medicine in St. Louis, Missouri, told Medscape Oncology. "We are finding that PET can help doctors make treatment decisions for patients."
The researchers used PET with the glucose analog F-18 fluorodeoxyglucose (FDG), a widely available 3-D scanning technique. FDG is reportedly the most commonly used PET scan and measures how rapidly tumors take up a radiolabeled glucose tracer — high uptake results in a stronger or brighter signal in the scan.
The researchers found that the higher the standard uptake value (SUV) for FDG in the primary tumor, the greater the rate of recurrence and the lower the rate of survival of patients.
SUV Seems to Be More Predictive Than Current Staging Protocols
Patient-related and tumor-related factors such as age, histologic features, volume of the tumor, and stage have typically been critical attributes for predicting patient outcome and overall survival for cervical cancer. "In our study," the researchers write, "these attributes had a less significant association with prognosis and outcome than the primary tumor maximum SUV."
During an interview, Dr. Kidd admitted that her group was surprised by the results. "We had noticed previously that patients with higher SUV tended to have worse outcomes," she noted. "But we hadn't anticipated that SUV would be more predictive than standard staging protocols."
Dr. Kidd cautioned that the study is retrospective, and the findings therefore are limited, but she says that the potential implications of the work are promising.
The investigators looked at 287 patients with cervical cancer treated with surgery, chemotherapy, or radiation after standard treatment protocols. At the time of diagnosis, researchers obtained the SUV of the primary tumors. Cancers were staged in accordance with standard guidelines and relied largely on the size of the tumor and involvement with surrounding tissues. The cancers ranged from early stage IA2 to highly advanced stage IVB.
Patients were categorized in 3 different risk groups: low, medium, and high. Those with the lowest SUV had a survival rate of 95% at 5 years, those in the middle SUV range had a 70% 5-year survival rate, and those in the highest SUV range had a survival rate of 44% at 5 years.
Dr. Kidd explains that because a high SUV indicates that tumors take up glucose rapidly, the measurement may point to an important biological difference in these more aggressive cancers. "We're interested in finding out why this difference exists," she told Medscape Oncology. "We're hoping this will eventually lead to new methods for treating patients."
The researchers have disclosed no relevant financial relationships.
Cancer. Published online September 4, 200