Endometrial Cancer Case Study
Clinical History
A 49 year old female patient with a diagnosis of endometrial carcinoma presented for restaging. She had previously been diagnosed with abdominopelvic metastasis from endometrial cancer and undergone a hysterectomy with lymph node removal in August 2004, followed by radiation therapy and chemotherapy. The patient had a previous history of vulvar carcinoma, which was diagnosed in 1998 and treated with local resection.
Initially, the patient underwent an abdominal CT scan for restaging. The CT scan was read as normal with a small amount of free fluid in the abdomen. The patient was referred for an FDG PET•CT scan for restaging and assessment of metastases.
Imaging Findings
Examination Protocol*:
NUCLEAR MEDICINE PET•CT Scan: 12/14/2006
SCANNER: Siemens Biograph 6 PET•CT scanner
STATED REASON FOR REQUEST: Endometrial cancer restaging RADIOPHARMACEUTICAL ADMINISTERED: 11.47mCi 18F FDG IV. TECHNIQUE: Emission scanning was obtained from the base of the skull through mid thighs, with delayed images of the pelvis obtained, approximately 90 minutes post radiotracer injection.
CT SCAN: Low dose, non-diagnostic and non-contrast, used for attenuation correction and anatomical localization only, and is not a diagnostic CT.
BLOOD GLUCOSE: 88mg/dl.
Imaging Findings PET•CT Scan 12/14/06:
The PET•CT evaluation of the abdomen and pelvis revealed a hypermetabolic right paraaortic lymph node at the level of the renal veins, measuring 1.7 x 1.5 cm (red arrow). The finding was consistent with metastatic disease. No other abdominal or thoracic or skeletal metastases were visualized.
Further Review of CT Scan 12/8/06:
In view of the PET•CT findings, a review of the CT images was performed. After correlation with the metabolically active foci identified on the PET•CT scan, a 1.7 x 1.5 cm, enhancing, retrocaval node, suspicious for metastatic disease was identified on the CT images.
Diagnosis
The PET•CT scan revealed hypermetabolic right paraaortic adenopathy consistent with malignancy.
Treatment
In view of the paraaortic lymph node metastases, the patient was put on a second course of chemotherapy. Without PET•CT the patient would have been classified as disease free because of the absence of significant CT findings.
Discussion
PET•CT identified an area suspicious for malignancy and caused the reader to go back and review the prior CT scan. An addendum was made to the prior CT report, initiated by the PET•CT findings.
The limitations of CT imaging for identification of recurrence of uterine carcinoma is related to the inability of CT to differentiate between malignant lymph nodes and reactive hyperplasia, and between recurrence and post therapy fibrosis. Early nodal metastases and local recurrence may also escape detection by CT because of the small size of the lesion. In one study of 56 women the accuracy of CT in endometrial cancer (1) was evaluated. The patients had preoperative CT scans and lymph node samplings. Positive and negative predictive values for nodal involvement were 50% and 94%, respectively, and sensitivity and specificity were 57% and 92%, respectively. Thirty-seven women had CT scans for suspicion of recurrence, which was confirmed in 17 (46%).
PET•CT, in comparison, has been shown to be of higher accuracy for detection of recurrence. In a recent study involving 25 patients studied with PET•CT and using histopathology as the standard for recurrence detection (2), the sensitivity and specificity of FDG PET•CT was 92.9% and specificity 100%.
The specificity and accuracy of PET•CT has been proven to be substantially higher than PET only. In a retrospective case series (n=34), Belhocine et al. (3) noted that FDG PET had a sensitivity of 96% and a specificity of 78% for post-therapy surveillance and led to alteration in treatment in 35%. Saga et al. evaluated 30 scans in postoperative patients (4) and found a sensitivity of 100%, with the treatment plan being affected in 33.3%. A recent study by Chao et al. (5) showed that the sensitivity of FDG PET alone (87%) or FDG PET plus MRI-CT (91%) was significantly higher than that of MRI-CT alone (67%) in overall lesion detection. Furthermore, the accuracy of FDG PET plus MRI-CT was significantly higher than that of MRI-CT alone.
The high sensitivity of FDG PET in recurrence detection, combined with increased specificity due to use of PET•CT, justifies the inclusion of PET•CT as the first line modality for post operative evaluation of endometrial carcinoma and should improve management decision making and outcomes.
Data courtesy of Dr. Charles Intenzo and Dr. Sung Kim, Jefferson Center City Imaging, Philadelphia, PA
References:
1. Computed tomography in endometrial carcinoma - Connor JP et al. - Obst Gynaecol 2000 May;95(5):692-6
2. Post therapy surveillance of patients with uterine cancers: value of integrated FDG PET/CT in detection of recurrence - Sironi et al. - EJNM 2007;34:472-9
3. Usefulness of FDG PET in post therapy surveillance of endometrial carcinoma - Belhocine et al. - EJNM 2002;29:1132-9
4. Clinical value of FDG PET in the follow up of postoperative patients with endometrial cancer - Saga et al. - Ann Nucl Med 2003;17:197-203
5. 18F-FDG PET in the management of endometrial cancer - Chao et al. - EJNM 2006;33:36-44
* Any of the protocols presented herein are for informational purposes and are not meant to substitute for clinician judgment in how best to use any medical devices. It is the clinician that makes all diagnostic determinations based upon education, learning and experience.