CT scans have no influence on clinical decisions in bladder cancer treatment
MedWire News: Multi-detector row computerized tomography (MDCT) has a low accuracy in predicting the correct tumor and nodal stage in bladder cancer patients, report researchers.
Preoperative staging by MDCT therefore has little impact on the decisions clinicians make regarding the extent of lymphadenectomy and the type of urinary diversion required before they proceed with radical cystectomy, say Stefan Tritschler (University of Grobhadern, Munich, Germany) and colleagues.
As reported in the World Journal of Urology, the researchers conducted a study involving 276 patients who underwent radical cystectomy after preoperative staging by CT scan, between April 2004 and June 2008.
Data on the pathologic tumor stage (categorized by TNM [tumor, nodes, metastasis] classification), the number of removed lymph nodes, and the type of urinary diversion performed were compared with the preoperative MDCT findings.
These referred to the depth of tumor invasion and were categorized as: organ-confined tumor (pT0-PT2), tumor with extravesical growth (pT3), tumor with infiltration of extravesical organs (pT4), and infiltration of the bladder by an extravesical tumor.
Iliac lymph node involvement according to MDCT was also assessed, where nodes with an axis diameter of 10 mm or more were defined as "lymph node positive" and those with a diameter of less than 10 mm as "lymph node negative."
The researchers report that the accuracy of the MDCT findings in predicting the local tumor stage was only 49.0% (Kappa coefficient=0.23), with overstaging occurring in 23.4%, and understaging in 24.7%.
The urinary diversions performed included an ileal conduit, an ileal neobladder, and a pouch in 147, 105, and five patients, respectively.
There was a significant correlation between the pathologic local and nodal stage and the type of urinary diversion performed, with more ileal conduits carried out in cases of high tumor stage (>pT2) and positive lymph nodes.
However, there was no such correlation between CT-defined tumor stage and the urinary diversion performed. "The CT finding did not have any influence on this clinical decision," write Tritschler et al.
The study also revealed that the accuracy of the MDCT findings in predicting lymph node metastases was only 54.0% (Kappa coefficient=0.04) with overstaging occurring in 8.3% and 29.4%, respectively.
During lymphadenectomy, a median of 10 lymph nodes were removed. Again, the researchers found no correlation between the preoperative CT tumor stage and the number of removed lymph nodes. "CT did not play any role in this clinical decision either," they remark.
The authors say that while CT scan has proven to reliably identify distant metastases and upper-tract tumors, it has little value in prediction of correct local and nodal stage.
"Alternative diagnostic tools are warranted to enable urologists to identify those patients who are eligible for alternative treatment modalities," they conclude.
By Sally Robertson