Abstract
OBJECTIVE To evaluate the role of whole-body {18F}fluro-2-dexoxyglucose (FDG) positron emission tomography (PET) scans in the detection of recurrent cervical cancer.
METHODS Between June, 2000 and January, 2006, 25 patients had undergone a PET scan at the Peking Union Medical College Hospital to evaluate possible recurrent cervical cancer. All the PET findings were reviewed and compared to available clinical data to classify each PET scan result as a true positive, true negative, false positive, or false negative.
RESULTS A total of 38 PET scans were conducted on the 25 patients whose median age was 46 years. The Stage distributions were IA (n = 1), IB (n = 11), IIA (n = 5), IIB (n = 4), IIIB (n = 2), IVB (n = 1), and unknown Stage (n = 1). There were 22 cases of squamous cell carcinoma and 3 cases of adenocarcinoma resulting in 9 true positive PET scans, 27 true negatives, 2 false positives and no false negatives. The sensitivity of the FDG PET scans for detecting recurrent cervical cancer was 100%, specificity 93.1%, positive predictive value 81.8%, and negative predictive value 100%.
CONCLUSION The whole body FDG PET scans are a sensitive and specific imaging modality for the detection of recurrent cervical cancer. However the cost of PET scans is too high at this time. A large prospective study will determine whether this modality should be used routinely and take the place of other imaging methods in the early detection of recurrent cervical carcinoma
keywords
Introduction
Since more and more Pap smears have been used as a method for early diagnosis of cervical neoplasms, most cervical carcinomas are found in an early stage. However 20~40% of the cervical cancers are still found at a late Stage (IIa~IVb). Patients are treated for cervical cancer by either a radical hysterectomy or radiotherapy. Usually following treatment is finished, the methods for follow up are very limited. Recurrent cervical cancer is a devastating disease for those women unfortunate enough to suffer such an event. Early detection of a localized disease that can be treated with either radiotherapy or pelvic exenteration often offers the only chance for complete eradication of the disease. Usually a pelvic examination, Papanicolaou smear, and chest radiography are used for diagnosis of a recurrence. Whole-body positron emission tomography (PET) using the glucose analog{18F} fluoro-2-dexoxyglucose (FDG) has been demonstrated to be useful in the staging of cervical cancer, being superior to either CT or MRI for detection of nodal disease. The detection of nodal disease, especially periaortic nodal disease provides the basis for individual treatment, and is a significant prognostic factor for survival.
In the present study, we evaluated the clinical usefulness of whole-body FDG-PET scans in detecting recurrent cervical cancer in women with or without symptoms.
Patients and Methods
This study involved 25 patients who received medical care at the Peking Union Medical College for Cervical Cancer, and who had undergone PET scan imaging in an attempt to detect recurrent cancer between June, 2000 and January, 2006. A minimum of 6 months follow-up after the post treatment PET scan was required to be included in this study. The International Federation of Gynecology and Obstetrics (FIGO) classification was used for clinical staging.
Recurrent diseases were confirmed in all cases with either tissue biopsy or the demonstration of a progressive disease by CT. Clinical proof of no recurrent disease consisted of a negative tissue biopsy, negative CT, or a lack of clinical evidence of recurrence within 6 months of the PET scan.
Results
The 25 patients underwent a total of 38 PET scans for surveillance purposes or because of the development of symptoms suggestive of a tumor recurrence. The ages of the patients ranged from 31 to 80 years, with a mean of 46. Patient FIGO staging was as follows: IA 1, IB 11, IIA 5, IIB 4, IIIB 2, and IVB 1. Only one patient was not staged. The pathological types of cervical carcinoma were 22 cases of squamous carcinoma and 3 cases of adenocarcinoma. Twenty patients received a radical hysterectomy, and others underwent radiotherapy. Eight patients were given neoadjuvant chemotherapy before surgery.
True positive PET scans were found 9 times (23.7%) and false positives were found in 2 patients (5.3%). True negative scans were found 27 times (71.1%), but there were no false negatives. So in this study, the sensitivity of PET scanning for the recurrence of cervical cancer was 100% and the specificity 93.1%. The positive predictive value and negative predictive value were 81.8% and 100% respectively. The 8th patient listed in Table 1 was given a PET scan twice. Cases 9 and 10 were confirmed to be false positives. All cases with positive PET scans are listed in Table1.
Summary of cases with positive PET scans.
Patient No.9 was a 39 year old woman with a IB staged squamous carcinoma. She received a radical hysterectomy and during follow-up the CT scan showed there was a cyst in the pelvis. The patient then was given a PET scan afterward, the result of which also showed there was a cyst in the pelvis under the abdominal incision. This patient underwent an operation after all these examinations only to find that the pathological results showed there were no cancer cells, but rather inflammation of the tissue and new dilation of the left ovarian paragraph duct. Case No.10 was a 39 year old woman with stage IB squamous carcinoma. She received a radical hysterectomy and radiotherapy after the operation. During the follow-up for one year, she was given a PET scan without any symptoms. The result showed positive lymph notes near the bladder, but neither the pelvic examination nor the CT scan showed a pelvic mass. The patient was followed-up for 5 years and all the examinations were normal.
Discussion
It is important to diagnose a recurrence of cervical cancer as early as possible. Early diagnosis for isolated metastases can be given curative therapy. It is estimated that approximately 35% of the patients with invasive cervical cancer will have recurrent or persistent disease after therapy[1-3]. The diagnosis of recurrent cervical cancer is often difficult to establish. After radical hysterectomy, about one-fourth of recurrences occur locally in the upper part of the vagina or the area previously occupied by the cervix. The location of recurrences after radiation therapy developed 76% locally and 24% at a distance[4-6]. Unfortunately, most recurrences can not be diagnosed early. The purpose of this study was to inves-tigate the usefulness of PET scan imaging in the early detection of recurrent disease in patients previously treated for cervical cancer[7-9].
Unfortunately, women with symptomatic recurrent cervical cancer have limited treatment options and often do not survive their disease. Early detection of recurrent disease has the potential to improve survival for these women, although this remains unproven by this study. Bodurka et al.[1] have shown that for women with recurrences, survival is better for asymptomatic women compared to symptomatic women.
Havrilesky et al.[8] have reported the results similar to ours by finding sensitivity for PET scans to be 86%. Rose et al.[9] reported the sensitivity of PET scan to be 90%. Clearly PET scans are useful in detecting recurrent disease in women with cervical cancer[10-12].
Are other diagnostic evaluations better than PET, such as CT scans? In Park’s study[13], they found PET was much better than CT by reporting that the sensitivity and specificity of CT scans was 77% and 83% respectively, and the sensitivity and specificity of PET scans was 100% and 94% respectively. Rose et al.[9] indicated that PET was better than CT for lymph node detection. Unfortunately, as shown in our study, the majority of these women had disease that was no longer localized to the pelvis. CT is also an important method to detect the metastatic sites. Due to any number factors however we can not conclude whether PET scans are better than CT. Ours was a small series, and therefore it may lack adequate power to detect small differences. Also this was a retrospective study and surveillance PET scans were performed at varying intervals after treatment was completed.
It is clear that PET scan imaging is useful in the detection of recurrent cervical carcinoma in symptomatic and asymptomatic patients. PET scans post-therapy in asymptomatic patients for surveillance purposes appears promising, but it is more expensive than other procedures and must await further study with prospective, standardized protocols before it is can be recommended for routine use. To improve survival in women with recurrent cervical carcinoma is a challenge for all gynecologic clinicians.
- Received July 11, 2007.
- Accepted January 7, 2008.
- Copyright © 2008 by Chinese Anti–Cancer Association
In this issue
Jump to section
Related Articles
Cited By...
- No citing articles found.