Damian McNamara

June 15, 2016

SAN DIEGO — ¹⁸F-fluorodeoxyglucose PET integrated with CT (¹⁸F-FDG PET/CT) scans over and above the three that are typically reimbursed by the Centers for Medicare & Medicaid Services might be justified when a physician suspects a recurrence of breast cancer in a patient, new research shows.

"The most important part is the impact on management," said Sara Sheikhbahaei, MD, MPH, from Johns Hopkins University in Baltimore.

"When there is clinical suspicion, a PET scan changes management in about one-third of patients. Without suspicion, it's about 6%," she told Medscape Medical News.

In a previous study Dr Sheikhbahaei was involved with, it was shown that "you can predict survival with high accuracy and can change patient management" with more than three ¹⁸F-FDG PET/CT scans in lung cancer patients (J Nucl Med. 2016;57:855-860).

On this basis, she and her colleagues decided to retrospectively evaluate breast cancer patients who had undergone more than three post-treatment scans.

Dr Sheikhbahaei presented the results during a poster session here at the Society of Nuclear Medicine and Medical Imaging 2016 Annual Meeting. Full details of the study were published in the June issue of Nuclear Medicine Communications.

In their analysis of 92 women with breast cancer, the investigators looked at patient records immediately before and after each scan to assess any impact the scans had on patient management, such as the continuation of one treatment or the addition of a new treatment.

Patients were followed for a median of 2 years after the fourth post-treatment scan to determine diagnostic accuracy and the impact of the scans on clinical assessment or survival.

"We found that the fourth and subsequent PET scans have high positive predictive value, negative predictive value, and diagnostic accuracy," Dr Sheikhbahaei reported.

Table. Accuracy of the Fourth and Subsequent PET/CT Scans

Measure Percent
Sensitivity 97.7
Specificity 98.1
Positive predictive value 98.8
Negative predictive value 96.3
Accuracy 97.9


Of the 426 PET/CT scans assessed, 264 (62%) were interpreted as being positive and 162 (38%) were interpreted as being negative.

Not surprisingly, there was a significant difference in overall survival between patients with all negative follow-up scans and those who had at least one positive follow-up scan (hazard ratio for death, 4.65; log-rank P < .001).

The fourth and subsequent follow-up PET/CT scans helped to exclude a tumor in 39 of 292 patients (13.4%) with a clinical suspicion of recurrence. They also identified recurrence in 14 of 134 of patients (10.5%) without clinical suspicion.

Scans changed management in 81 of the 292 patients (27.7%) with a clinical suspicion of recurrence or insufficient response to therapy. However, when there was no clinical suspicion, scans changed management in only nine of 134 patients (6.7%).

"The results of this study make sense to me, especially for the use of PET to monitor bone metastasis," said David Mankoff, MD, PhD, from the University of Pennsylvania in Philadelphia.

"PET can be an effective way to manage patients with metastatic breast cancer who have a prolonged disease course," he told Medscape Medical News. "In these patients, PET studies beyond three scans can be quite helpful."

Dr Sheikhbahaei and Dr Mankoff have disclosed no relevant financial relationships.

Society of Nuclear Medicine and Molecular Imaging (SNMMI) 2016 Annual Meeting: Abstract 1498. Presented June 13, 2016.


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