Challenges in the treatment of bladder cancer

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Abstract

Seventy to eighty percent of patients with newly-diagnosed bladder cancer will present with superficial tumors (Ta, Tis or T1). There is, however, a continuum between superficial and muscle-invasive cancer, with the advanced cases usually associated with less-differentiated histology and aneuploidy. Common sites of metastasis include regional lymph nodes, bone, lung, skin and liver. From the low cure rates achieved with radical cystectomy, there is strong evidence that bladder cancer, from the outset, is a systemic disease. The limitations of local treatment are well-documented: a local control rate of 30% with radiation treatment, and 50–70% with radical cystectomy; and no improvement in surgical cure was seen with the use of preoperative radiation. Over the past 30 years, since the initial reports of the effectiveness of cisplatin in the treatment of advanced bladder cancer, there has been a steady flow of chemotherapeutic agents, singly and in combination, shown to be effective in the treatment of this tumor. While response rates and CR rates have increased with the use of combination chemotherapy, this has not translated into survival in advanced disease of greater than 16 months. While the search for more effective agents and combinations continues, attention has also been given to the roles of neoadjuvant and adjuvant chemotherapy in an effort to improve the cure rate achieved with surgery alone. Although radical cystectomy, with continent diversion or neobladder construction in selected cases remains the standard of care in the United States for patients with muscle-invasive bladder cancer, several groups have explored therapeutic strategies that aim at bladder preservation. Early approaches with the goal of bladder preservation consisted of radiation treatment as monotherapy (largely abandoned) or aggressive TURBT for smaller tumors. Over the past 20 years, the Massachusetts General Hospital (MGH) and the Radiation Therapy Oncology Group (RTOG) have studied patients with muscle-invading bladder cancer utilizing tri-modality treatment: a visibly complete transurethral resection followed by radiation with concurrent radiosensitizing chemotherapy and, subsequently, adjuvant chemotherapy. Thus, chemotherapy has been used in two phases of treatment (1) as radiosensitizers, given concurrently with radiation treatment and (2) as adjuvant treatment, recognizing that survival will only be improved by the successful treatment of micrometastases. Based on preliminary information from reports of the effectiveness of gemcitabine/cisplatin in advanced disease, that combination was chosen as the adjuvant regimen in one of our earlier protocols, recently completed and reported. Our current protocol utilizes the Bellmunt regimen as our adjuvant program with the highest RR in advanced disease. This study is ongoing, with early reports of tolerance of the three-drug regimen encouraging. The treatment options for muscularis propria-invasive bladder tumors can broadly be divided into those that spare the bladder and those that involve removing it. In the United States, radical cystectomy with pelvic lymph node dissection is the standard method used to treat patients with this tumor.

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