A controlled trial of misonidazole in the curative treatment of infiltrating bladder cancer

Hypoxia and its Modification in Bladder Cancer: Current and Future Perspectives

Radiotherapy plays an essential role in the curative treatment of muscle-invasive bladder cancer (MIBC). Hypoxia affects the response to MIBC radiotherapy, limiting radiocurability. Likewise, hypoxia influences MIBC genetic instability and malignant progression being associated with metastatic disease and a worse prognosis. Hypoxia identification in MIBC enables treatment stratification and the promise of improved survival. The most promising methods are histopathological markers such as necrosis; biomarkers of protein expression such as HIF-1α, GLUT-1 and CAIX; microRNAs; and novel mRNA signatures. Although hypoxia modification can take different forms, the gold standard remains carbogen and nicotinamide, which improve local control rates in bladder preservation and absolute overall survival with no significant increase in late toxicity. This is an exciting time for evolving therapies such as bioreductive agents, novel oxygen delivery techniques, immunotherapy and poly (ADP-ribose) polymerase 1 (PARP) inhibitors, all in development and representing upcoming trends in MIBC hypoxia modification. Whatever the future holds for hypoxia-modified radiotherapy, there is no doubt of its importance in MIBC. mRNA signatures provide an ideal platform for the selection of those with hypoxic tumours but are yet to qualified and integrated into the clinic. Future interventional trials will require biomarker stratification to ensure optimal treatment response to improve outcomes for patients with MIBC.

Radiotherapy in bladder cancer

In the present review, we have evaluated the outcome of radiotherapy in patients with bladder cancer. The exact value of radical radiotherapy is difficult to establish because changes in treatment techniques and selection of patients have biased the results. The 5-year survival rates are reported to be 35-71% in T1 tumors, 27-59% in T2 tumors, 10-38% in T3 tumors and 0-16% in T4 tumors. Several other factors, like performance status and hemoglobin level, are important for the outcome. Morbidity of radical radiotherapy depends on several treatment and patient related factors, but 50-75% experience acute intestinal or urological symptoms and 10-20% may develop severe late toxicity, depending on the kind of registration. The importance of field size or overall treatment time cannot be established from available data. Hyperfractionation with dose escalation has proven effective in one study. Preoperative radiotherapy with cystectomy has not proven better than cystectomy alone or better than radiotherapy alone. The addition of systemic chemotherapy has increased disease-free survival, but has not significantly reduced the rate of distant metastases or improved overall survival. Presently, the standard radiation regimen is a conventional dose and fractionation schedule to a total dose of 60-66 Gy with a three- or four-field technique covering the bladder and tumor. The efficacy of additional irradiation of regional lymph nodes is questionable. New treatment possibilities with advanced techniques of radiotherapy, hyperfractionation and dose escalation and/or the addition of systemic chemotherapy may improve outcome. These options should be further explored in clinical trials.

The management of invasive bladder cancer: a review of selected Australasian studies in radiotherapy, chemotherapy and cystectomy

Since 1968, studies have been conducted in Australia and New Zealand to improve the results of treatment for invasive bladder cancer. The prognostic value of clinical stage and of ureteric obstruction has been confirmed. Radiotherapy has been established as appropriate treatment for the majority of patients with bladder cancer, most of whom are elderly and suffer from other health problems. There has been no additional benefit from radiosensitizers in increasing the effectiveness of radiotherapy such as hyperbaric oxygen or misonidazole, or from irradiation of the para-aortic nodes, all of which can result in additional toxicity without increasing tumour control. Pre-emptive chemotherapy with cisplatin has had no obvious impact on improving survival. Elective total cystectomy has shown the prognostic value of tumour downstaging by pre-operative pelvic radiotherapy. Although younger patients are usually selected for total cystectomy and urinary diversion, there is no evidence that, stage for stage, elective total cystectomy confers a survival advantage compared with radical pelvic radiotherapy.