Abstract
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Objectives PET/CT has become a critical tool in the evaluation of lymphoma and is now standard of care in the functional evaluation of tumor burden, metabolic response to therapy and early detection of disease recurrence. This retrospective review evaluates the utility of surveillance scans in lymphoma patients in order to assess the average time to recurrence, if it occurred.
Methods 93 patients with 523 serial PET/CT scans performed between April 2003 and December 2010 were selected for this study. The series of scans analyzed began with the first negative study after treatment (eg. surgery, chemotherapy and/or radiation) and ended with the first positive study that was indicative of recurrence. If recurrent disease did not occur, the series was followed out to the last recorded PET/CT on file. A total of 113 series were identified.
Results Of the 523 PET/CT studies performed, a total of 47 scans (9.0%) demonstrated true positive recurrence. On average, recurrent disease was detected on day 379. The first positive PET/CT’s (n = 8; 16%) occurred 80 days after the initial negative study; the last positive scan occurred on day 1200. Lastly, of the 113 series analyzed, 66 series remained negative with no evidence of recurrence; on average, these series of scans were followed out for 831 days.
Conclusions The initial results indicate that surveillance scans in lymphoma patients exhibit the most utility after 80 days, or approximately 2.5 months. In fact, the majority of studies demonstrating disease recurrence occurred by 300 days, or 10 months, after the initial negative study. If disease recurrence was not documented by day 1200, the remaining patients were likely to remain in remission. Additionally, only 9.0% of all PET/CT studies performed actually demonstrated recurrence; this raises concern about the cost-effectiveness of surveillance scans in lymphoma patients