PET-CT HAS PREDICTIVE VALUE AFTER RADIOCHEMOTHERAPY FOR HEAD AND NECK CANCERS

Oncologists at St. John Hospital in Grosse Pointe Woods, Michigan, routinely perform a surveillance positron emission tomography (PET)/computed tomography (CT) scan 6 to 9 weeks after the definitive chemoradiation treatment of patients with squamous cell carcinoma of the head and neck — even when a recurrence is not clinically suspected.
And these clinicians will continue to do so in light of the results from a small study conducted at their center, despite the "controversy" surrounding such routine follow-up, said study author Yasir Rudha, MD, MBChB, a radiation oncologist at the hospital.
"We will keep doing it because of the high negative predictive value," said Dr. Rudha during a press conference at the 2012 Multidisciplinary Head and Neck Cancer Symposium. He was referring to the fact that, in their study, about half of the patients with no clinical evidence of recurrence had a subsequent negative surveillance scan and that all of them remained free of locoregional recurrence on further follow-up.
"Almost all of those patients will be able to avoid neck dissection," predicted David Raben, MD, from the University of Colorado in Aurora, about patients with negative surveillance scans. He was moderator of the press conference. In the past, most of these patients would have automatically gone on to a neck dissection as part of treatment, he said.
The surveillance scans had another benefit — they identified patients with disease recurrence that preceded any clinical manifestation of recurrence. The rate for finding these "true positives" was 53%, Dr. Rudha reported. However, this benefit was somewhat offset by the "high false-positive rate" of 46%, he admitted.
"The routine use of PET/CT scanning in the follow-up of patients with squamous cell carcinoma of the head and neck may be useful for the detection of locoregional recurrences before they become clinically apparent," he summarized.
Study Results and Controversies
Dr. Rudha and colleagues identified 234 patients with head and neck cancer at their center who were treated with chemoradiation and then underwent a posttherapy PET/CT scan from 2006 to 2010.
A retrospective chart review was performed for 45 of those cases, all of whom had a "clinical no-evidence-of-disease " status at the time of the surveillance PET/CT scan.
Of these 45 patients, 30 had a negative PET/CT scan, and all 30 remained free from locoregional relapse at the time of last follow-up. However, the median time of follow-up for the 30 patients was not presented by Dr. Rudha.
The scans identified 15 patients with abnormalities requiring further evaluation. Biopsy showed malignancies in 8 of the 15 patients (53%). (Six of the 8 showed occult persistent disease at the primary site.)
The other 7 cases of abnormalities turned out to be false positives (46%). Thus, patients underwent "unnecessary work-up and/or biopsy evaluation," he said. "Caution should be shown when ordering biopsies after abnormal scans to prevent excessive unnecessary biopsies," he added.
However, overall, the study results provide "support for the routine use of PET scanning as a surveillance method following treatment of head and neck cancer," Dr. Rudha summarized.
Dr. Rudha suggested that this is an uncommon finding in the literature.
He acknowledged that, in most studies, PET scans are performed only when recurrent disease is clinically suspected. "Only a few publications report the value of PET examination at a fixed time after the end of treatment," he told reporters at the press conference.
Dr. Raben endorsed using PET after treatment. The scans are "absolutely critical" for the monitoring and follow-up of these patients. But he added that the use of PET scans in head and neck cancer "continues to evolve."