SNM 2009: Two-Year FDG-PET/CT Follow-Up Useful in Patients With Hodgkin's Lymphoma in Complete Remission

Louise Gagnon

June 15, 2009

June 15, 2009 (Toronto, Ontario) — Patients with Hodgkin's lymphoma would benefit from fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) surveillance in the first 24 months after achieving remission of their cancer but not after that point, according to research presented here at the Society of Nuclear Medicine 56th Annual Meeting.

"We wanted to know if it really makes sense to scan patients every year because patients are asking for it," said Nicklaus Schaefer, MD, a postdoctoral fellow in the Department of Radiology at Johns Hopkins Medical Institute/Johns Hopkins University in Baltimore, Maryland, who conducted his research as a medical resident at the University Hospital of Zurich in Switzerland. "Most of the patients that are being referred [for radiographic surveillance] are not symptomatic, and they don't have any sign of recurrent disease."

Given the burden of radiation that additional scans represent and the fact that it is not clear if early detection of recurrent disease makes a difference in overall survival, Dr. Schaefer and colleagues retrospectively examined the utility of FDG-PET/CT surveillance.

"When we looked at the data, we found that the symptoms and residual disease are very strong predictors [of recurrence]," explained Dr. Schaefer, who proposed in his oral presentation that surveillance be practiced in the first 2 years after complete remission of Hodgkin's lymphoma. "Those predictors were time-dependent."

A total of 135 Hodgkin's lymphoma patients, 85 of whom were asymptomatic and 50 of whom were symptomatic, and all of whom had complete remission of their disease after receiving primary treatment, received FDG-PET/CT to screen for active disease. A total of 43 patients had positive FDG-PET/CT, and of that total, 42 experienced a histologically confirmed relapse (positive predictive value, 0.98). Symptoms included B-symptoms, new palpable masses, and new masses diagnosed by conventional imaging.

Investigators found that asymptomatic patients with residual masses (n = 25) or with residual masses and advanced initial stage (n = 19) had more recurrences than patients with early-stage disease without residual masses (n = 27) (respectively, 6 vs 0 patients [P < .008] and 5 vs 0 patients [P < .001]).

A total of 31 symptomatic patients exhibited recurrence on FDG-PET/CT and 30 had histological confirmation (positive predictive value, 0.97). The remainder of symptomatic patients showed no signs of recurrence and did not experience relapse during the follow-up period (mean, 22.7 months).

"If we carefully select our patients, we will have a strong rate of detection of recurrence," said Dr. Schaefer. "If we don't use our resources wisely, they will be reduced."

Gregory Wiseman, MD, a consultant in nuclear medicine at the Mayo Clinic in Rochester, Minnesota, noted that the study is limited by its design, but it raises the issue of a lack of standardization in using surveillance among Hodgkin's lymphoma patients.

"Some people use surveillance and some don't," said Dr. Wiseman. "[The study] is retrospective, so it makes it a little bit harder to interpret. What we really need to do is conduct a prospective study of patients who are followed [with FDG-PET/CT] and those who aren't to determine how useful it is. It is still possible because it's not routine that these patients undergo surveillance."

A prospective trial would also separate Hodgkin's lymphoma patients who have received radiation treatment from those who have not, said Dr. Wiseman, noting the effects of radiation therapy can affect the outcomes of FDG-PET/CT imaging.

"All the patients in this study had chemotherapy," said Dr. Wiseman. "People should not make conclusions based on patients in this study and apply it to patients who have undergone radiation."

The study was independently conducted. Dr. Schaefer and Dr. Wiseman have disclosed no relevant financial relationships.

Society of Nuclear Medicine (SNM) 56th Annual Meeting: Abstract 48. Presented June 15, 2009.
J Nucl Med. 2009;50(suppl 2):13P.


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