FDG-PET/CT image depicting liver metastases in a patient with inflammatory breast cancer. Image source: RSNA (Carkaci et al)

FDG PET/CT may have a potential role in asymptomatic breast cancer patients with rising markers and negative conventional imaging, according to a multicenter study published May 21 ahead of print in the European Journal of Radiology.

“Tumor markers are sensitive in detecting recurrent or residual disease but imaging is required to customize the therapeutic option. Rising tumor markers and negative conventional imaging (ultrasound, mammography, CT and MR) poses a management problem,” according to Gaia Grassetto, MD, from the department of nuclear medicine at Santa Maria della Misericordia Hospital, Rovigo, Italy, and colleagues, who conducted the study.

In the period from January 2008 to September 2009, 89 female patients with breast cancer who developed post-therapy rising markers (serum Ca 15-3 levels=64.8U/mL) but were considered negative for the presence of tumoral deposits by clinical exam, mammography, chest-abdomen contrast-enhanced CT scan, abdominal ultrasound and whole-body bone scintigraphy in other centers, using different techniques were referred to Santa Maria della Misericordia Hospital in Rovigo, Italy to perform 18F-FDG PET/CT for further investigation.

The researchers detected tumor deposits in 40 of the 89 patients within the chest wall, internal mammary nodes, lungs, liver and skeleton. The mean maximal standard uptake value (SUVmax) value calculated in these lesions was 6.6. In 23 of the 40 patients, solitary small lesion were amenable to radical therapy. In seven out of these 23 patients, a complete disease remission lasting more than one year was observed, the authors noted.

“Another observation from our study is that we did not find a significant difference between serum Ca 15-3 levels in FDG positive when compared to FDG-negative patients. Moreover, no relationship was found between the site of FDG-positive metastatic deposits and SUVmax,” wrote Grassetto and colleagues.

The authors reasoned that the majority of the patients scanned were on hormonal therapy and it cannot be excluded that hormonal therapy has influenced serum Ca 15-3 levels.

Around 45 percent of the patients in the study revealed a metastatic lesion on 18F-FDG PET/CT and in 58 percent of those, 18F-FDG PET/CT showed a solitary small lesion with the potential to be treated by radical approach, according to Grassetto and colleagues.

“Our findings agree with other studies in promoting regular investigations such as tumor markers and 18F-FDG PET/CT rather than awaiting the developments of physical symptoms as suggested by current guidelines since the timely detection of early recurrence may have a major impact on therapy and survival,” concluded the authors.