Is carboplatin (Carboplatin) less effective than cisplatin (Cisplatin) for treating bladder cancer?

From the Guidelines

Carboplatin is generally considered inferior to cisplatin for bladder cancer treatment in patients who can tolerate cisplatin. Cisplatin-based combination chemotherapy regimens (such as gemcitabine plus cisplatin, or dose-dense MVAC) remain the standard of care for muscle-invasive bladder cancer and advanced disease, with higher response rates and improved survival outcomes compared to carboplatin-based regimens, as supported by the most recent guidelines from the National Comprehensive Cancer Network 1. The superiority of cisplatin stems from its mechanism of action, which creates stronger DNA cross-links and induces more effective cancer cell death.

However, carboplatin is an appropriate alternative for patients who cannot receive cisplatin due to poor kidney function (creatinine clearance <60 mL/min), hearing loss, neuropathy, heart failure, or poor performance status. When carboplatin is used, it's typically combined with gemcitabine at a dose calculated using the Calvert formula (AUC 4-5) every 3 weeks. While carboplatin offers reduced nephrotoxicity, ototoxicity, and neurotoxicity compared to cisplatin, these benefits come at the cost of decreased efficacy against bladder cancer and increased myelosuppression, particularly thrombocytopenia, as noted in studies comparing the two agents 1.

Key points to consider in the choice between carboplatin and cisplatin include:

• Patient tolerance and ability to receive cisplatin
• Presence of comorbidities such as renal impairment, hearing loss, or neuropathy
• Performance status of the patient
• Specific characteristics of the bladder cancer, including stage and grade
• Availability and suitability of alternative treatments, such as checkpoint inhibitors for patients who are not candidates for platinum-based chemotherapy 1.

In summary, cisplatin remains the preferred choice for bladder cancer treatment when possible, due to its superior efficacy, but carboplatin is a viable alternative in specific clinical scenarios where cisplatin is not tolerated or is contraindicated, as supported by the evidence from 1, which is the most recent and highest quality study on this topic.

From the Research

Efficacy of Carboplatin vs Cisplatin in Bladder Cancer Treatment

• The study published in 1997 2 found that the carboplatin-based regimen M-CAVI is less toxic but less active than the cisplatin-based regimen M-VAC in the treatment of patients with advanced bladder carcinoma.
• A 1996 study 3 compared the efficacy and toxicity of a cisplatin-containing regimen with a carboplatin-containing regimen for patients with recurrent or metastatic bladder cancer, and found that the cisplatin-containing regimen had a higher overall clinical response rate and more pronounced side effects.
• However, a 2022 study 4 found no significant survival benefit for cisplatin over carboplatin as first-line chemotherapy in metastatic urothelial carcinoma of the bladder after accounting for all known prognostic factors.
• A 2013 study 5 investigated the safety and activity of carboplatin combined with gemcitabine as a neoadjuvant chemotherapy for patients with locally advanced bladder cancer, and found that it had less non-hematologic toxicity and less nephrotoxicity compared to a cisplatin-based regimen.

Toxicity and Renal Function

• The 1997 study 2 found that M-VAC was associated with more gastrointestinal toxicity, stomatitis, alopecia, and Grade 4 neutropenia than M-CAVI.
• The 2013 study 5 found that the carboplatin-based regimen had less nephrotoxicity and non-hematologic toxicity compared to the cisplatin-based regimen.
• A 2011 review 6 discussed the challenges of treating bladder cancer in patients with impaired renal function, and noted that the perception that carboplatin-based combinations are inferior to cisplatin-based combinations is probably incorrect.

Overall Response Rates and Survival

• The 1997 study 2 found that the overall response rates were 39% for M-CAVI and 52% for M-VAC.
• The 1996 study 3 found that the overall clinical response rate was 71% for the cisplatin-containing regimen and 41% for the carboplatin-containing regimen.
• The 2022 study 4 found that the median overall survival was 13.1 months for the cisplatin group and 11.5 months for the carboplatin group, with no significant difference after adjusting for prognostic factors.