An analysis of the contribution of computed tomography to the treatment outcome in bladder cancer

Features of Irradiated Urinary Bladder Tumors and Their Correlation with Malignancy Observed on Computed Tomography

CT features of 42 masses in the bladder wall were characterized and subjected to analysis to find indicators of malignancy. A CT technique with thin slices and intravenous contrast medium was used. Multiple regression and multivariate analysis showed good ability of contrast-enhanced CT to discriminate between benign and malignant masses in the bladder wall. Protrusion of a mass into the perivesical fat had some importance in discriminating between malignant tumors with and without perivesical growth although the detection of perivesical growth was less certain.

Radiation Therapy for Muscle-invasive Bladder Cancer: Treatment Planning and Delivery

Radiation therapy allows organ preservation therapy in selected patients with muscle invasive bladder cancer. This review sets out to explore the role of radiation therapy in the management of muscle invasive bladder cancer. It describes and assesses the potential benefits provided by technological advances in radiation delivery in optimizing the therapeutic ratio.

Conformal radiotherapy of urinary bladder cancer

Recent advances in radiotherapy (RT) are founded on the enhanced tumour visualisation capabilities of new imaging modalities and the precise deposition of individualised radiation dose distributions made possible with the new systems for RT planning and delivery. These techniques have a large potential to also improve the results of RT of urinary bladder cancer. Major challenges to take full advantage of these advances in the management of bladder cancer are to control, and, as far as possible, reduce bladder motion, and to reliably account for the related intestine and rectum motion. If these obstacles are overcome, it should be possible in the near future to offer selected patients with muscle invading bladder cancer an organ-sparing, yet effective combined-modality treatment as an alternative to radical surgery.

Improving and predicting radiosensitivity in muscle invasive bladder cancer

PURPOSE

Muscle invasive bladder cancer is a common urological malignancy with a relatively poor prognosis and 5-year survival rates ranging from 20% to 90%. We review methods of improving the outcome of this condition, with particular emphasis on the principal bladder preserving treatment modality of radiation therapy.

MATERIALS AND METHODS

We performed a literature search using MEDLINE and the ISI Web of Science using the keywords radiotherapy, radiosensitization and bladder neoplasia to ascertain the current status of radiation therapy and radiosensitizing agents in the treatment of muscle invasive bladder cancer.

RESULTS

Several methods aimed at improving outcome following radiation therapy for muscle invasive bladder cancer are described. These methods range from modifications in the application of radiation therapy to use of conventional radiosensitizing agents, such as accelerated radiotherapy with carbon dioxide, oxygen and nicotinamide, and finally to use of more novel agents that interact with oncogenic products. The use of assays that predict tumor sensitivity on an individual basis represents an additional potential method to improve prognosis following radiation therapy.

CONCLUSIONS

The ability to predict tumor radiosensitivity and the subsequent implementation of radiosensitizing techniques are likely to improve the results of treatment centered on radiation therapy, suggesting that bladder sparing approaches will remain a treatment option for muscle invasive bladder cancer.

Changes in target volume during radiotherapy treatment of invasive bladder carcinoma

Ninety patients with stage T3 Nx Mo carcinoma of the urinary bladder were treated with radical megavoltage external beam radiotherapy. Planning for treatment was undertaken on a treatment planning system utilizing CT scan slices to define the target volume and patient outline. All patients underwent a second CT scan half way through their course of treatment to assess any change in target volume and the continued adequacy of the original treatment plan. Seventy-two patients (80%) had no spatial shift in target volume, but, of the 18 patients with such a shift, treatment plans were changed in seven. The majority of patients had no delay in continuing their treatment after replanning, but one patient had a gap of 5 days before restarting treatment. An analysis of the factors possibly associated with a change in target volume showed that a primary tumour at the bladder base, rather than elsewhere in the bladder, was the single most important criterion for predicting target volume changes. There was no correlation between the size of the initial tumour, or the size of the prostate gland in male patients, and the occurrence of a shift in volume outside the initial target volume. Some method of regularly assessing the continued relevance of the target volume may be needed in this group of patients to improve the precision of treatment and also improve results.

Planning of radiotherapy for patients with hip prosthesis

The effects of a hip prosthesis on the dose distribution when treating pelvic cancer have been evaluated. A prosthesis of titanium alloy in a water phantom was used as a model. Photon radiation beams with energies of 6, 20, and 50 MV and with a focus phantom distance of 100 cm were directed against the prosthesis. The dose profiles at different depths were measured with the RFA-7 system. The sphere of the prosthesis was inhomogeneous. The dose in a beam behind the prosthesis was reduced with the order of 10-40% and the largest distortion was behind the shaft. Using an opposed four-field technique with the same weight on all the fields, the dose reduction was as large as 7-12% in a string across the target behind the end of the shaft. With 50% weight on the lateral fields, the dose reduction was 4-8% of the average dose. Such an uneven dose distribution may decrease the curability, and a treatment technique not including the prosthesis should be preferred. Finally, a local increase of the dose close to the prosthesis seems to be of limited practical concern even at the highest energies.

Assessment of factors influencing the outcome of radiotherapy for bladder cancer

The results of treatment of 709 patients with carcinoma of the bladder are reported. Inclusion of the pelvic lymph nodes in the treatment volume failed to lead to any improvement in survival. The factors influencing survival were stage, tumour histology and differentiation. The presence of tumour at follow-up cystoscopy at 3 months was of great prognostic significance.