International variations in childhood cancer in indigenous populations: a systematic review.
Valery PC, Moore S, Meiklejohn J, Bray F. The Lancet Oncology, Volume 15, Issue 2, Pages e90 - e103, February 2014, doi:10.1016/S1470-2045(13)70553-9
http://www.thelancet.com/journals/lanonc/article/PIIS1470-2045%2813%2970553-9/fulltext
全てのがんの頻度だとあまり変わらないががんの種類は違う
