449 Background: An increased incidence of both RCC and HM occurring in the same patients has been reported. Also, a relationship between adenocarcinoma and HM has been previously suggested. Moreover, detailed family history in our patients with RCC suggested an increased incidence of HM in their family members. The purpose of this study is to characterize the HM in relatives of patients with RCC. Methods: Data from 700 patients with RCC seen by us from 2004 to the present were retrospectively evaluated through chart review. The patient, family history and pathology characteristics were collected to determine the frequency of HM in first and second-degree relatives of patients with RCC. Pedigrees were then constructed and subtypes of HM were characterized. Results: A family history of HM was observed in 74 relatives involving 59 families. Of these, 50/74 cases of HM were in first-degree relatives and 19/74 were in second-degree relatives. The most common HMs were lymphoma and leukemia: 24 non-Hodgkin’s lymphoma, 8 Hodgkin’s lymphoma, 8 lymphoma not further specified (NOS), 11 chronic lymphocytic leukemia, 1 chronic myeloid leukemia, 1 acute myeloid leukemia, 5 acute leukemia NOS and 4 leukemia NOS. Other HM observed were multiple myeloma in 2 patients, Waldenström’s macroglobulinemia, myelodysplastic syndrome, and myelofibrosis. Additionally, 2 relatives had blood cancers that were NOS. Of the 59 patients with RCC, 40 had clear cell histology, 4 papillary, 3 chromophobe, 1 sarcomatoid, 1 transitional and in 10, RCC histology was not recorded. Conclusions: HM is observed in patients with RCC with increased frequency compared with the SEER database. We now observed an increased frequency of HM in relatives of patients with RCC. The majority of HMs observed were B-cell malignancies, as we previously reported for HMs that occur in patients with breast cancer or RCC. The etiology of this association remains unclear, but suggests a common etiopathogenesis for RCC and B-cell tumors. Genetic mutations, hereditary immunological defects, and environmental factors may be involved. A larger study with statistical evaluation for confirmation is required. We plan to collect serum and tissue samples from patients and relatives for future molecular studies.
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