Cervical cancer staging

SAN DIEGO -- Spiral computed tomography performs as well as MRI in staging cervical cancer before surgery, Dr. Karuna P. Murray reported at the annual meeting of the Society of Gynecologic Oncologists.

In fact, this latest advancement in rapid continuous CT scanning may eventually become the presurgical staging modality of choice, because it's faster, simpler, and less expensive than MRI, said Dr. Murray formerly of the University of Minnesota, Minneapolis.

In a head-to-head study aimed at comparing spiral computed tomography (SCT) and MRI, Dr. Murray and colleagues staged the cancers of 28 women with both imaging technologies before surgery.

MRI and SCT were each able to determine the presence or absence of lymph node metastases in 25 of the 28 cases.

SCT predicted parametrial extension of disease with an accuracy rate of 79%; the accuracy rate for MRI was 78%.

Overall, the evaluations yielded information on 13 patients (46%) that would have upgraded their cancer to a higher stage than initially suspected, said Dr. Murray who is now with St. Louis University.

Although imaging studies of gynecologic malignancies have historically relied on conventional CT, MRI was used as the bench mark in this study because it is currently considered the best single modality for staging cervical carcinoma, Dr. Murray said.

In addition, compared with conventional CT scanning, SCT yields significantly better spatial resolution and enhancement of organ vasculature and tissue planes, because it captures retrograde images from the pubis symphysis to the diaphragm in 0.5-cm sections and from the bladder to the cervix interface in 3-mm sections.

Generally, the error rate in surgical staging with MRI is 8%-25%, compared with 42%-70% for conventional CT. Error rates for SCT have yet to be determined.

Error rates for clinical staging of cervical carcinomas range from 24% to 39% for early-stage disease and from 65% to 90% for late-stage disease. A total of 23 of the 28 study participants had early-stage disease.

In this study, one radiologist read all the MRI images; a second radiologist interpreted the SCT scans. Both were blinded to the clinical stage of disease and the other radiologic image results.

Larger studies involving multiple radiologists are needed to confirm the usefulness of SCT in comparison with the more costly and cumbersome MRI and before SCT can be used routinely, she said.