RSNA: Is the quest for evidence prohibiting PET/CT from being included in breast cancer guidelines?

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CHICAGO—When an audience member asked why PET/CT is not already included in the clinical oncologic guidelines for the management of locally advanced breast cancer, two expert panelists at the annual Radiological Society of North America (RSNA) meeting explained that the push for conclusive, evidence-based medicine may be one consideration.

“Medical oncologists are inherently conservative, and currently, there is a push throughout all of healthcare to have their clinical practices based upon evidence, which means they require rather large data sets to be comfortable that there is a benefit from performing even a diagnostic test,” explained Steven M. Larson, MD, vice chair for research for the radiology department at Memorial Sloan-Kettering Cancer Center in New York City.

As an example, Larson referenced the realm of pancreatic cancer. “Gemcitabine [Gemzar, Eli Lilly] is a drug that offers only a small improvement in five-year survival, from 10 to 20 percent,” he said. Yet, that drug is recommended because there is no evidence that a combination of other drugs will have the same survival impact.

To be included in clinical guidelines, “it’s a matter of collecting data in a way that is convincing to the medical oncology community because they are the ones ordering the tests,” Larson said.  

His fellow panelist, Homer Aquino Macapinlac, MD, a radiologist in the nuclear medicine department at MD Anderson Cancer Center in Houston, concurred. “Sometimes the requirement for evidence-based medicine has come to the point of being silly.” He used the analogy of parachutes, that although there are no conclusive studies, most people will want the protection of the device. “Some medical concepts may be inherently obvious to us, but [medical oncologists] still want the data,” he added.

Most oncologists are looking for trials, according to Macapinlac, which would randomize breast cancer patients to PET/CT or no PET/CT, and follow them for a long time, up to 10 years, because these patients can live for a long time.  

Macapinlac also pointed to economics, as guideline writers and regulators are hesitant to recommend a therapy that would increase costs, acknowledging that PET/CT is a “fairly costly exam.”

However, he added that the efficacy of the exam may drive its acceptance for certain cancer patients, as PET/CT has been adopted with lymphoma patients. “With breast cancer, recurrence can occur several times over the course of the patient’s life, so the exam won’t demonstrate a survival benefit, as clearly as it may with other types of cancers.”