Challenges of tuberculosis in cancer patients: insights from two hospitals in Madrid

Tuberculosis (TB) and cancer share overlapping clinical features that may worsen outcomes when coexist. We aimed to characterize TB in cancer patients and identify predictors of TB-related mortality in a low TB-prevalence setting.

We conducted a 15 year retrospective cohort study (2010-2024) across two hospitals in Madrid. Patients with microbiologically confirmed TB during cancer treatment or within the preceding 2 years were included. Clinical and demographic variables were analyzed to identify factors associated with adverse outcomes.

Eighty-eight cancer patients were diagnosed with TB (median age 62.5 years); 70.5% were male and 17% were immigrants. Immunocompromising conditions were present in 61.3%. Solid tumors predominated (75%), with lung cancer being the most frequent. TB was diagnosed after cancer in 68.1% of cases, and 93.9% of isolates were drug susceptible. Atypical presentations were observed in 68.8% of patients. After excluding six cases of BCGitis, overall and TB-related mortality were 28.0% and 12.1%, respectively. Patients who died had longer diagnostic delays (185.82 vs 69.48 days, p=0.03). Synchronous diagnosis of TB and cancer emerged was the only independent predictor of mortality (p=0.01), whereas no TB-related deaths occurred when TB was incidentally detected during cancer reassessment. Among the 33 patients tested, a positive interferon gamma release assay (IGRA) was associated with better outcomes, potentially reflecting preserved immunity.

TB in cancer patients frequently presents atypically and is associated with diagnostic delays and substantial mortality. Proactive and systematic diagnostic strategies are warranted. Negative or indeterminate IGRA results should not exclude active TB.