Second cancer incidence in primary mediastinal B-cell lymphoma treated with methotrexate with leucovorin rescue, doxorubicin, cyclophosphamide, vincristine, prednisone, and bleomycin regimen with or without rituximab and mediastinal radiotherapy: Results from a monoinstitutional cohort analysis of long-term survivors.

Our aim is to assess the incidence of second cancer in long-time surviving primary mediastinal B-cell lymphoma (PMBCL) patients treated with combined radiochemoimmunotherapy (standard methotrexate with leucovorin rescue, doxorubicin, cyclophosphamide, vincristine, prednisone, and bleomycin with rituximab and mediastinal radiation therapy at a dose of 30 to 36 Gy). For this purpose, 92 points were evaluated. After a median overall survival of 137 months (range 76-212), we recorded second cancer in 3 of 80 long-surviving patients (3.75%) with cumulative incidence of 3.47% at 15 years and 11% at 17 years, with a 17-year second cancer-free survival of 82%. We observed 2 papillary thyroid cancers with a standardized incidence ratio (SIR) of 7.97 and an absolute excess risk (AER) of 17. 84 and 1 acute myeloid leukemia (AML) with an SIR of 66.53 and an AER of 10.05. No breast cancer occurred. Although we should take into account the limits of the proposed statistical analysis, combined modality treatment was related to a significant SIR and AER for thyroid cancer and acute myeloid leukemia.