Risk of hemolymphopoietic neoplasm before and after thyroid cancer. a population‐based study in italy, 1998‐2012

Introduction: The number of patients living after a cancer diagnosis is increasing, especially after hemolymphopoietic and thyroid cancer (TC). This study aims at evaluating both the risk of a second hemolymphopoietic cancer in TC patients and the risk of TC as a second cancer. Methods: Two population-based cohorts of cancer patients aged up to 84 years were identified from 28 Italian cancer registries in the 1998–2012. The first included TC patients and the second hemolymphopoietic cancers patients with cancers. Standardized incidence ratios (SIR) of SPC were stratified by sex, age, and time since first cancer. SPC diagnosed within 2 months since first are not included in the computation of cancer-specific SIRs. Results: 38,535 TC patients and 154,820 patients with hemolymphopoietic cancers were included. Overall SIR for hemolymphopoietic cancer in TC patients was significantly increased (SIR=1.5 in women and 1.3 in men), as well as for most of the hemolymphopoietic subtypes (SIR=2.7 for acute lymphoid leukemia, 1.6 for follicular non-Hodgkin lymphomas, 1.5 for chronic lymphoid leukemia, and 1.4 for myelomas for both sexes). The overall SIR for hemolymphopoietic cancer in TC patients was significantly higher in all three age groups (0-34 years: 2.0, 35-54: 1.4 and 55+: 1.4 for both sexes). The risk of TC cancer was significantly increased after Acute Lymphoid Leukemia (10 cases, SIR=6.1), Hodgkin lymphomas (38, 2.8), and all hemolymphopoietic neoplasms (183, 1.8). The risk of TC after any hemolymphopoietic cancer was particularly higher for the age groups 0-34 and 35-54 (SIR 4.3 and 1.8 respectively). Conclusions: TC patients have both an increased risk of developing a second hemolymphopoietic cancer as TC to be a second cancer. An elevated risk of second primary tumors from the use of radioactive iodine (RAI) therapy in TC patients, in particular in pediatric and young adult patients, may explain the elevated incidence of acute lymphoid leukaemias and hemolymphoiectic neoplasms overall. The present finding may help in designing surveillance programs for hemolymphopoietic cancers in TC patients and vice versa keeping into consideration the possibility of overdiagnosis of TC. Keywords: Prevention and Cancer Interception No conflicts of interests pertinent to the abstract.