Background Patients who respond to therapy are considered ‘statistically cured’ when their life expectancy returns to the same level as that of the general population i.e. they no longer experience excess mortality. With an estimated 4870 new diagnoses in the UK each year, diffuse large B-cell lymphoma (DLBCL) is one of the few blood cancers that is potentially curable with intensive chemo-immunotherapy; but information about the subsequent mortality of survivors is sparse. To fill this gap, we employed a cure modelling approach to estimate the 5-year survival and cure fraction (CF; the proportion of patients considered statistically cured) of patients with DLBCL in an established UK population-based patient cohort.

Methods Data are from from the UK’s Haematological Malignancy Research Network (HMRN, www.hmrn.org), which has been tracking all patients diagnosed with a blood cancer or related disorder in a catchment population of ~4 million people since 2004. Demographic, treatment and outcome data were examined in all patients (18+ years) newly diagnosed with DLBCL between 2005-2019 (n= 3920). Mixture cure models, where it is assumed a proportion of patients are cured and the remaining are not, with a Weibull parametric distribution, log link function for the CF, and age-, sex- and deprivation-matched general population mortality rates obtained from UK life tables, were used to calculate the 5-year survival and CF. Estimates and 95% confidence intervals (CI) were calculated in STATA 18.0.

Results Median age at diagnosis of DLBCL was 70 years, 53.0% of patients were male, and 45.8% presented at stage IV. The majority of patients received intensive chemotherapy as a first-line treatment (82.5%), 12.4% of patients received supportive or palliative care only, and the remaining 5.1% of patients received other therapies. Of the patients who received intensive chemotherapy as a first line treatment, 78.3% responded, meaning there was an improvement in their DLBCL. The 5-year survival for DLBCL patients was 61.5% [CI: 59.7-63.3], and the CF was 44.8% [CI: 39.8-49.8]. The CF was lower in men than in women (37.2% [CI: 27.0-48.7] vs. 49.8% [CI: 44.7-54.8]).

Conclusion Life expectancy returned to the same level as that of the general population for 44.8% of DLBCL patients, and were considered statistically cured. The model will be explored further with a conditional survival approach, to estimate the cure fraction for patients who responded to intensive chemotherapy.