In monitoring colorectal cancer (CRC) patients after curative-intent surgery, the use of more sophisticated and sensitive imaging does not decrease subsequent failure rates compared to use of older technology, according to a new multicenter randomized trial from France.
However, use of F-18 fluorodeoxyglucose positron-emission tomography (18FDG-PET) CT, a newer and expensive imaging tool, did increase costs, report Iradj Sobhani, MD, of the Universite Paris-Est Creteil-Val de Marne, and colleagues.
The study was published online January 22 in the Annals of Oncology.
Early detection of recurrences improves outcomes, say the investigators, but the best way to conduct monitoring is an open question, they say.
So the team compared a “usual” monitoring regimen based on current French and international standard guidelines, which included use of CT alone, to a monitoring approach that employed that same standard plus 18FDG-PET/CT.
As a single tool, PET/CT combines a PET scanner and the older technology of an x-ray CT scanner. The two technologies create separate images that are then fused into a single image.
In the trial, postsurgery CRC patients whose disease was in remission were randomly allocated to receive either 3-monthly physical and tumor marker assays, 6-monthly liver ultrasonography and chest radiography, and 6-monthly whole-body CT (ie, usual monitoring) or usual monitoring plus 18FDG-PET/CT every 6 months.
Follow-up lasted 3 years. The patients had either stage II perforated, stage III, or stage IV CRC.
The primary endpoint was treatment failure, which was defined as unresectable recurrence or death. The hypothesis was that the more sensitive and sophisticated imaging would detect recurrences earlier and decrease the failure rate.
But that did not happen.
The investigators enrolled 239 patients: 120 in the 18FDG-PET/CT intervention arm, and 119 in the usual-monitoring control arm.
The absolute failure rate was 29.2% (31 unresectable recurrences and four deaths) in the intervention group and 23.7% (27 unresectable recurrences and one death) in the control group (relative risk = 1.23; P = .34). A multivariate analysis showed no significant difference between groups (hazard ratio, 1.33; P = .27).
Notably, median time to diagnosis of unresectable recurrence was significantly shorter in the intervention group (7 months vs 14.3 months; P = .016).
However, the mean cost per patient was significantly higher in the intervention group (€18,192 ± 27,679 vs €11,131 ± 13,254; P < .033).
The secondary endpoints of overall survival (OS) and disease-free survival (DFS) were not significantly different between groups.
This study reinforces our current practice of not using routine PET scan for surveillance.
“This is a well-designed, prospective study that reinforces our current practice of not using routine PET scan for surveillance,” said Iris Wei, MD, a surgeon at Memorial Sloan Kettering Cancer Center in New York City, who was asked for comment.
The primary endpoint of treatment failure (ie, unresectable recurrence or death) is “reasonable with a short 3-year follow-up,” she explained.
Wei was intrigued by one finding. She highlighted the fact that the secondary endpoint of time to first unresectable recurrence was significantly shorter in the intervention group (7 vs 14.3 months). “This shows that even with earlier identification, short-term outcomes are no different,” she said.
One of the study’s limitations concerned the fact that most previous studies that investigated postsurgery CRC monitoring used OS or DFS as their primary outcome, whereas this study used subsequent failure rates. Thus, comparing outcomes is not straightforward.
However, the current results are strong with regard to complete follow-up (all patients but one) and appropriate sample size (the study was not underpowered).
The new results add to a checkered literature on this subject. Whether or not more intensive monitoring strategies improve the outcomes of CRC patients is “controversial,” the authors say.
“Considerable heterogeneity across studies may explain the discrepancies in results. An intensive monitoring strategy was compared to less intensive investigations in some studies and to no follow-up at all in others,” they observe.
The authors conclude that use of 18FDG-PET/CT in these patients is “not advised” after surgery unless there are other relevant factors are present, such as elevations in the levels of tumor markers.
The study was funded by the French Ministry of Health. The authors and Dr Wei have disclosed no relevant financial relationships.
Ann Oncol. Published online January 22, 2018. Abstract
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