What happens when cancer patients receive PET-CT instead of CT alone?

For women with locally advanced cervical cancer, PET imaging, in addition to conventional CT scans, can give physicians a more detailed look at lymph node metastases. A small clinical trial in Canada showed that using both imaging methods can lead to more extensive chemotherapy and radiation therapy, but the difference was not significant.

In a study published online Sept. 14 in JAMA Open Network, the researchers noted how the use of PET impacted therapy, but the lack of significant findings was due to the study being “underpowered.”

"We met our goal of determining whether adding PET detects more extensive disease and influences treatment,” according to principal investigators Lorraine Elit, MD, MSc, and Anthony Fryles, MD. “The study showed that patients who had PET were twice as likely to have a change in their treatment."

The study included 171 women newly diagnosed with cervical cancer between 2010 and 2014, with 112 receiving PET imaging along with standard CT scans, which could detect additional cell activity and potential cancer growth.

“[T]here was an increased rate of detection of para-aortic or common iliac adenopathy identified with PET-CT,” the authors wrote. “This resulted in a two-fold increase in radiation to extrapelvic nodes in patients in the PET-CT group, although this difference was not statistically significant, likely as a result of the small sample size due to prematurely discontinued recruitment.”

The study was stopped early thanks to a slow rate of recruitment, according to the authors. Still, while the results are not statistically significant, they show PET imaging could impact therapy.

“Although our trial was underpowered, it is reasonable to consider the results within the context of the National Comprehensive Cancer Network recommendations that are based on observational data,” Elit at al. wrote. “Our results provide higher-quality evidence to support current practice. Finally, a prudent and efficient approach might be to consider PET-CT only for patients with abnormal pelvic nodes on CT.”