Guidelines versus real-world data in metastatic bladder cancer: A population-based study on first-line chemotherapy treatment patterns.

Background: For patients with metastatic bladder cancer (mBC) palliative chemotherapy is one of the main treatment options. Real-world insights into outcomes are available, but a comprehensive overview of specific treatment details like number of chemotherapy cycles received and (reasons for) adjustments is lacking.

Methods: A population-based study was conducted, including all patients diagnosed with mBC in the Netherlands between 2016 and 2021 who started chemotherapy as initial treatment. Data on patient, tumor, and treatment characteristics, including number of cycles, adjustments and reasons for adjustments, and survival were collected from the Netherlands Cancer Registry. Treatment patterns and outcomes were analyzed descriptively. Logistic regression analysis was used to identify factors associated with receiving the full guideline-recommended treatment (4-6 cycles).

Results: A total of 684 patients started first-line chemotherapy, mostly carboplatin-based (54%). Of these patients, 35% did not receive the full course of treatment. Among these patients who received <4 cycles, 24% died within one month of stopping treatment. Male sex and good performance status were independently associated with receiving the full course of treatment. Among patients who did receive a full course of treatment, half still had adjustments to their treatment schedule, which mainly included dose reductions due to side effects.

Conclusions: Among patients with mBC starting first-line chemotherapy, only a small majority received the recommended number of cycles, and treatment adjustments were common. This suggests that adhering to recommended treatment is challenging, emphasizing the importance of integrating insights on treatment discontinuation and modifications into the shared decision-making process and guideline development.