Concordance in survival among first-degree relatives diagnosed with indolent lymphoid malignancies including chronic lymphocytic leukemia.

Objectives: To investigate concordance in survival time among first-degree relatives with lymphoid malignancies.
Methods: By linkage of national Swedish registers, we identified 66 430 patients diagnosed with a lymphoid malignancy 1958-2016 with information on first-degree relationships and follow-up until 2017. Among these, we identified pairs of first-degree relatives with any (N = 3326) or a similar (N = 690) lymphoid malignancy subtype. We defined survival in the first-degree relative as good, expected, or poor based on tertiles of deviance residuals from a multivariable Cox regression model. Next, we used Cox regression to estimate hazard ratios (HR) of death with 95% confidence intervals (CI) among patients, using the survival of their first-degree relative as exposure and adjusting for confounders.
Results: There was no concordance in survival among first-degree relatives with any lymphoid malignancy (HR _good  = 1.00 (reference), HR _Expected  = 1.02, 95% CI: 0.89-1.17, HR _Poor  = 1.12, 95% CI: 0.98-1.27, P _trend  = .08). Among first-degree relatives with indolent lymphoma, including chronic lymphocytic leukemia, those with a first-degree relative to an expected or poor survival had worse outcome compared to those with a first-degree relative with good survival (HR _Expected  = 1.44, 95% CI: 0.82-2.53, HR _Poor  = 1.79, 95% CI: 1.07-3.00, P _trend  = .03).
Conclusion: Our results support a role of inherited factors in the outcome of indolent lymphoma, including chronic lymphocytic leukemia.
(© 2020 The Authors. European Journal of Haematology published by John Wiley & Sons Ltd.)