This book offers an accessible yet authoritative introduction to the rare and complex cancers diagnosed within the first year of life. Addressing conditions such as neuroblastoma, leukemia, retinoblastoma, congenital mesoblastic nephroma, and early brain tumors, this concise volume explores how these malignancies differ biologically and clinically from those in older children and adults. With a focus on the unique developmental origins and genetic underpinnings of infantile cancers, the book examines the challenges of early diagnosis, the urgency of effective treatment, and the delicate balance required to protect the rapidly developing infant body. It highlights advances in genomic research, targeted therapies, and survivorship care while underscoring the critical need for family-centered, multidisciplinary approaches. Drawing on current research and clinical practice, this book is an invaluable resource for healthcare professionals, students, and researchers seeking to understand and improve outcomes for the youngest patients facing cancer.