¹⁸F-FDG PET/CT and Colorectal Cancer: Value of Fourth and Subsequent Posttherapy Follow-up Scans for Patient Management

Abstract

The purpose of this study was to evaluate the added value of a fourth and subsequent follow-up PET/CT scans to clinical assessment and impact on patient management in patients with colorectal cancer. Methods: This was an institutional review boardapproved, retrospective study. Eight hundred twenty-two patients with biopsy-proven colorectal cancer, who underwent 18 F-FDG PET/CT, were identified from 2000 to 2012. Among these, 73 (8.9%) patients underwent 4 or more follow-up PET/CT scans, with a total of 313 fourth and subsequent follow-up PET/CT scans. Median follow-up from the fourth follow-up PET/CT scan was 41.7 mo. The added value of each follow-up PET/CT scan, for clinical assessment and the treatment changes subsequent to each follow-up PET/CT scan, was established. Overall survival prediction was established using Kaplan-Meier plots with a Mantel-Cox log-rank test. Results: Of the 313 fourth and subsequent follow-up PET/CT scans, 174 (55.6%) were interpreted as positive and 139 (44.4%) were interpreted as negative for recurrence or metastases. Thirtyfour (46.6%) patients died during the study period. PET/CT identified recurrence or metastasis in 40.0% of scans obtained without prior clinical suspicion and ruled out disease in 23.6% of scans obtained with prior clinical suspicion. The PET/CT scan resulted in treatment change after 34.2% (107/313) of the scans. New treatment was initiated after 24.0% (75/313) of the scans, and treatment was changed after 8.0% (25/313) scans. There was a statistically significant difference in the overall survival between patients with a positive and all negative fourth and subsequent follow-up PET/CT scans at the patient level (log-rank, P 5 0.001). Conclusion: The fourth and subsequent 18 F-FDG PET/CT scans obtained after primary treatment completion add value to clinical assessment and the management plan and provide prognostic information in patients with colorectal cancer.

Value of Intratumoral Metabolic Heterogeneity and Quantitative 18F-FDG PET/CT Parameters to Predict Prognosis in Patients With HPV-Positive Primary Oropharyngeal Squamous Cell Carcinoma

“…Kaplan–Meier survival curves and the Mantel-Cox log-rank test were performed. Statistical significance was set at two tail p=0.05 for all tests 27,28 .…”

The value of fourth and subsequent post-treatment 18F-FDG PET/CT scans in the management of patients with non-Hodgkin’s lymphoma

“…The inference from this CMS decision is that more than three follow-up scans must be justified by medical necessity, for each tumor type, in each patient. We have previously published the value of fourth and subsequent 18 F-FDG PET/CT follow-up scans in patients with lung cancer and colorectal cancer [16,17]. To the best of our knowledge, the value of fourth and subsequent 18 F-FDG PET/CT scans after initial therapy in patients with NHL has not been evaluated.…”

“…This was established from the last clinical note of the treating physician requesting the study before the scan and the follow-up notes of the physician after the scan. The impact of the PET/CT scan on the treatment strategy was classified into six categories as described previously [16]: (a) the patients received no treatment before the scan and the treating physician continued to observe the patient without treatment after the scan (no treatment to no treatment), (b) the patients received a specific cancer treatment before the scan and the treating physician continued the same treatment after the scan (treatment to continue the same treatment), (c) the patients received no treatment before the scan and the treating physician started new treatment after the scan (no treatment to new treatment), (d) the patients received a specific cancer treatment before the scan and the treating physician changed the treatment modality/ regimen after the scan (treatment to change in treatment), (e) the patients received a specific cancer treatment before the scan and the treating physician stopped the treatment after the scan (treatment to stop the treatment), and (f) the patient's management after the scan was unknown (treatment change unknown).…”

Clinical Indications and Impact on Management: Fourth and Subsequent Posttherapy Follow-up 18F-FDG PET/CT Scans in Oncology Patients

“…Any additional follow-up 18 F-FDG PET/CT scans (beyond 3) will be covered only at the discretion of local Medicare administrative contractors, justified by a medical necessity (6). Previously, we evaluated the role of fourth and subsequent follow-up 18 F-FDG PET/CT scans obtained after primary treatment completion, in different cancers, and the results showed that 18 F-FDG PET/CT significantly affects the management of these patients especially when there is clinical suspicion of recurrence before performing the scans (7)(8)(9)(10). This study aimed to investigate the common indications of medical necessity to perform a fourth and more follow-up 18 F-FDG PE/CT scans, which may have high impact on the management of patients with different cancers.…”

“…The indications were categorized in 4 groups: PET/CT for diagnosis of tumor recurrence (303/1,659, 18.3%), PET/CT before starting therapy for tumor recurrence (64/1,659, 3.9%), PET/CT to assess therapy response for tumor recurrence (507/1,659, 30.6%), and follow-up PET/CT after completion of treatment for tumor recurrence (785/1,659, 47.3%). Overall, fourth and subsequent follow-up 18 F-FDG PET/ CT scans resulted in change in management in 31.6% of the scans (356 of 1,128) when the scans were obtained for medical necessities (indications [1][2][3][4][5][6][7][8][9][10][11], and in 5.6% of the scans (30/531) when the scans were obtained without any medical necessity (indication 12). Conclusion: The fourth and subsequent PET/CT scans obtained after completion of primary treatment led to a change in management in 31.6% of the scans when acquired for appropriate clinical reasons.…”