For a study, researchers sought to compare the therapeutic impact of Bacille Calmette-Guérin (BCG) intravesical instillation in elderly and young bladder cancer patients. Using very extensive retrospective data from several Japanese institutes, the comparison was carried out using propensity score matching (PSM) without ending the death of older patients.

In total, 3,283 non-muscle-invasive bladder cancer patients diagnosed between 2000 and 2018 at 31 institutes were evaluated; 1,437 and 602 patients with high-grade T1 and Tis tumors were split into age groups of  ≥75 and <75 years, respectively. Before PSM, a multivariate analysis utilizing the Fine-Gray competing risks regression model was carried out, and after PSM, a cumulative incidence method survival analysis was carried out.

Age ≥75 years was an independent predictive factor for recurrence and progression in the pre-PSM series of high-grade T1 tumors (P =.015 and P =.013, respectively). No factors to predict recurrence and progression were discovered in the pre-PSM series with Tis tumor. The cumulative likelihood of recurrence following BCG intravesical instillation was substantially greater in patients aged ≥75 years than in patients aged <75 years in the post-PSM series of 870 high-grade T1 tumors (P =.008). High-grade T1 and Tis patients ≥75 years did not substantially vary from patients under the age of <75 in terms of the frequency of BCG withdrawal (P =.564 and P =.869).

After intravesical BCG instillation, older individuals with high-grade T1 bladder cancer had a considerably greater cumulative risk of recurrence than younger patients.