Few population-based estimates of incidence exist; most reports represent the experience of a single institution. These results are subject to selection bias because of referral patterns and can rarely be used to estimate incidence. Data from a U.S. Surveillance Epidemiology and End Results (SEER) Program study show the incidence of cancer in the first month of life to be 27 per million infants, similar to that seen in several European studies. This number includes cancers that begin in the last month or two of prenatal life, but are not diagnosed until birth. Therefore, the number is probably not significantly different from the incidence of cancer during the rest of the first year of life, which was 18 per million per month in that same study. The incidence of cancer during the first year of life is 223 per million per year, well above the incidence during the rest of the childhood years. Although cancer is uncommon during the newborn period, it can be concluded that it is no less common than it is during later childhood.

The mortality from cancer in the first month of life—six to eight per million per year—is substantially lower than the incidence. The majority of newborns with cancer survive the neonatal period.

Types of tumors seen in the neonatal period are listed in Table 67.1, which presents all neonatal tumors, both benign and malignant, seen at the Children’s Hospital of Los Angeles from 1958 to 1985. Hemangiomas, the most common benign lesion of infancy, are generally excluded from discussions of neonatal tumors and are not included here. While teratomas and other soft tissue tumors constitute the majority of all tumors, neuroblastomas, leukemias, and sarcomas account for the majority of cancers in this series.

Table 67.2 compares the distribution of cancers in neonates with that of infants up to 1 year of age and all children less than 15 years of age. Neuroblastoma is the most common cancer in neonates, accounting for over 50% of all cancers. Leukemias (13%), renal tumors (13%), and sarcomas (11%) are the next most common cancers. Overall, the cancers seen in neonates differ substantially from those seen during the rest of childhood when leukemias (31%), brain tumors (18%), and lymphomas (14%) predominate.

One-half of neonatal malignancies and an even larger percentage of benign tumors are diagnosed on the first day of life; the remainder present over the next month. Numerous lesions have been diagnosed prenatally by ultrasonography, a process that can influence obstetric management and survival of the infant. Neonatal tumors usually present as visible or palpable masses, whether they are malignant or benign (Table 67.3). Visible masses include hemangiomas, teratomas, benign soft tissue
tumors or sarcomas, and skin nodules from leukemia, neuroblastoma, or congenital viral infection. Hemangiomas are the most common of all neonatal “tumors,” occurring in as many as 2% of all newborns. When subcutaneous, hemangiomas are differentiated from solid tumors by their characteristic appearance. Often, deeper hemangiomas can be differentiated from solid tumors by their blood flow characteristics on magnetic resonance imaging. Though almost all resolve without therapy, some increase rapidly in size and present complex management decisions. Neonatal teratomas occur most commonly in the sacrococcygeal region. Other relatively common locations include the neck and midline of the face. They are usually benign but may contain malignant elements. Sarcomas may present as masses on almost any part of the body including the head, neck, trunk, and extremities. Sarcomas are often clinically indistinguishable from benign soft tissue tumors.