Number of Siblings and the Risk of Lymphoma, Leukemia, and Myeloma by Histopathology

Abstract

Epidemiologic evidence indicates that several markers of exposure to childhood infections are inversely associated with the risk of childhood leukemia and lymphomas. We used the Swedish Family-Cancer Database to assess the effects of number of siblings on the risk of nonHodgkin's (n = 7,007) and Hodgkin's lymphomas (n = 3,115), leukemias (n = 7,650), and multiple myeloma (n = 1,492) by histopathology. Poisson regression models included terms for age, sex, family history, period, and socioeconomic index. Having four or more siblings compared with none was associated with an excess risk of childhood acute lymphoblastic leukemia [ALL; rate ratio (RR), 2.11; P trend = 0.001], acute monocytic leukemia (RR, 2.51; P trend = 0.002), and multiple myeloma (RR, 1.34; P trend = 0.006). Having three or more older siblings compared with none decreased the risk of acute monocytic leukemia (RR, 0.35; P trend = 0.001) and childhood ALL (RR, 0.69; P trend = 0.01). The risk of Hodgkin's lymphoma for five or more older siblings compared with none was 0.41 (P trend = 0.003). Acute myeloid leukemia, chronic lymphocytic leukemia, and other lymphoproliferative malignancies were not associated with number of siblings. In conclusion, we found an excess risk of childhood ALL and acute monocytic leukemia in large families. However, for ALL, acute monocytic leukemia, and Hodgkin's lymphoma, younger siblings were strongly protected compared with older siblings. The remarkable protective effect of number of older siblings on acute monocytic leukemia is a novel finding of potential interest. Possible interpretations of our findings in the context of a putative infectious etiology are discussed. (Cancer Epidemiol Biomarkers Prev 2006; 15(7):1281 -6)

Lymphoma risk in livestock farmers: Results of the Epilymph study

“…Having older siblings and sibship size were reported as inversely associated with risk of various lymphoma subtypes, 26,28,30 and they might be related to rural lifestyles, and to child labor, which was not uncommon even in rural Europe up to the middle of the past century, as observed among the participants in our study. Such conditions would surrogate early exposure to human borne infections, and early environmental exposure to endotoxin.…”

“…Several authors have suggested the hypothesis that disturbances of the Th1/Th2 balance in the immune response might contribute to lymphoma development. 9,[24][25][26][27][28] Several transmissible agents, from animal origin, either bacterial or viral, can cause zoonotic diseases in humans. 2,29 However, only a few papers have evaluated the association between contact with livestock and subsequent risk of lymphoma; most findings of an increased risk were related to contact with cattle or swine, [9][10][11] whilst a reduced risk was reported with contact with sheep or poultry, rabbits and hare.…”

The familial risk of Hodgkin's lymphoma ranks among the highest in the Swedish Family-Cancer Database

“…Despite evidence suggesting a familial clustering of Hodgkin's lymphoma (HL), [1][2][3][4][5][6] there is no clear understanding on the relative contribution of genes and shared environmental factors, including childhood infections, 7,8 to familial risk. The rarity of familial HL has hampered a detailed analysis of the familial clustering and it has probably contributed to the variation even in recent risk estimates for first-degree relatives, such as 4.9 from Utah 5 and 3.27 from Iceland.…”

Childhood Determination of Hodgkin Lymphoma among U.S. Servicemen

“…In contrast, after adjustment for other determinants, the number, order, and proximity of sibs still differed dramatically between cases and controls (60)(61)(62)(63), and those differences are unlikely to have more than negligible bearing on the adult life experience.…”