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The management of suspected metastatic bladder cancer can be much improved with combined positron emission tomography (PET)/computed tomography (CT), even allowing some patients to keep their bladder.

Such patients are already routinely scanned with CT and magnetic resonance imaging (MRI), but adding a combined PET/CT scan should be considered to be part of the standard of care, say researchers reporting a new study.

Conducted retrospectively in 57 bladder cancer patients with suspected metastatic disease, the study found that the use of PET/CT resulted in changes to treatment plans in 68% of cases.

The study was highlighted at a press conference at the 2009 Genitourinary Cancers Symposium, which is cosponsored by the American Society for Clinical Oncology, the American Society for Radiation Oncology, and the Society of Urologic Oncology.

The changes in management all occurred after the patients had first received either a CT scan or MRI.

The changed treatment plans allowed for a multitude of clinical efficiencies. For example, the PET/CT-informed treatment plans negated a need for additional biopsy in 21% of patients, eliminated additional imaging in 21%, and changed organ-confined treatment to metastatic treatment in 19%.

The fact that PET/CT changed "management in bladder cancer is very, very important. In some cases in this study, it's clear that the technology allowed patients to keep their bladder, which would have otherwise been removed," said Howard Sandler, MD, chair of radiation oncology at the Samuel Oschin Cancer Institute, Cedars-Sinai Medical Center, in Los Angeles, California. Dr. Sandler moderated the press conference and was not involved with the study.

Addition to Standard of Care

CT and MRI are routinely used to monitor disease progression in patients with bladder cancer and should remain part of the standard of care, the study's lead author, Andrea Apolo, MD, a medical oncology fellow at Memorial Sloan-Kettering, in New York City, told Medscape Oncology.

"We are suggesting that PET/CT be used as an adjuvant to baseline CT or MRI," she said, explaining that CT and MRI provide purely anatomical interpretations of metastatic disease, whereas PET technology provides a functional study of disease by showing the metabolic activity of cancer cells.

We are suggesting that PET/CT be used as an adjuvant to baseline CT or MRI.

The savings from unnecessary testing and procedures would likely offset the additional costs of the PET scan, suggested Dr. Apolo.

"Our findings suggest that PET scanning has the potential to be a cost-effective imaging tool in patients with suspected or existing metastatic bladder cancer," she said in a statement.

PET/CT is More Accurate

In a review of 53 cases in the study, the investigators determined that PET/CT found more evidence of metastatic cancer in 40% of patients than was seen with either CT or MRI alone. In 18% of patients, PET/CT found less evidence. In 42%, there was no difference or no answer in the patient record.

"PET is more accurate than CT or MRI," said Dr. Sandler in an interview with Medscape Oncology.

The patients in the study had PET/CT scans for staging, treatment response, or evaluation of suspected metastasis.

The study included both a patient-based analysis and a separate organ-specific lesion-based analysis.

For the patient-based analysis, 46 patients had evaluable PET/CT scans followed by either biopsy (n = 22) or a CT or MRI scan (n = 24) to validate the PET/CT finding. Malignant disease was correctly diagnosed by PET/CT in 24 of 30 patients, for a sensitivity of 80%. PET/CT was negative in 15 of 16 patients without malignant lesions, for a specificity of 94%.

In the organ-specific lesion analysis, 133 individual lesions were evaluable; each was validated either by biopsy (n = 22) or subsequent imaging (n = 111). Overall PET/CT sensitivity was 88% and specificity was 91%. Organ-specific analysis (sensitivity/specificity) was evaluated for adrenal (100%/80%), bone (93%/100%), liver (83%/100%), kidney (100%/100%), lymph node (89%/80%), and soft tissue (100%/100%).

"We were very surprised by the high levels of sensitivity and specificity — they were higher than all previously reported studies," said Dr. Apolo, adding that the other studies used PET alone, not the combined PET/CT technology.

The PET/CT technology used in this study is the 18F-2-deoxyglucose PET.

Source: Medscape Medical news