Flavonoids comprise the most common group of plant polyphenols and provide much of the flavor and color to fruits and vegetables. More than 5000 different flavonoids have been described. The six major subclasses of flavonoids include the flavones (e.g., apigenin, luteolin), flavonols (e.g., quercetin, myricetin), flavanones (e.g., naringenin, hesperidin), catechins or flavanols (e.g., epicatechin, gallocatechin), anthocyanidins (e.g., cyanidin, pelargonidin), and isoflavones (e.g., genistein, daidzein). Most of the flavonoids present in plants are attached to sugars (glycosides), although occasionally they are found as aglycones. Interest in the possible health benefits of flavonoids has increased owing to their potent antioxidant and free-radical scavenging activities observed in vitro. There is growing evidence from human feeding studies that the absorption and bioavailability of specific flavonoids is much higher than originally believed. However, epidemiologic studies exploring the role of flavonoids in human health have been inconclusive. Some studies support a protective effect of flavonoid consumption in cardiovascular disease and cancer, other studies demonstrate no effect, and a few studies suggest potential harm. Because there are many biological activities attributed to the flavonoids, some of which could be beneficial or detrimental depending on specific circumstances, further studies in both the laboratory and with populations are warranted.

BACKGROUND. The etiology of most pediatric neoplasms remains elusive. Examination of population-based incidence data provides insight regarding etiology among various demographic groups and may result in new hypotheses. The objective of the current study was to present updated information regarding childhood cancer incidence and trends in the U.S. overall and among demographic subgroups, including Asian/Pacific Islanders and Hispanics, for whom to the authors' knowledge trends have not been previously examined. RESULTS. Between 1992 and 2004, a modest, nonsignificant increase in the averageannual incidence rate (APC, 0.4%; 95% CI, 20.1%-0.8%) was observed for all pediatric cancer diagnoses combined. There was a suggestion of an increase in leukemia (APC, 0.7%; 95% CI, 20.1%-1.5%), and acute lymphoblastic leukemia in particular (APC, 0.8%; 95% CI, 20.4%-1.9%), whereas rates for central nervous system tumors overall were stable (APC, 20.1%; 95% CI, 21.1%-1.0%); 2 joinpoints were observed for astrocytoma. Rate increases were noted for hepatoblastoma (APC, 4.3%; 95% CI, 0.2%-8.7%) and melanoma (APC, 2.8%; 95% CI, 0.5%-5.1%).Differences by demographic group (sex, age, and race/ethnicity) are also described.CONCLUSIONS. The observed trends reinforce an ongoing need for populationbased surveillance and further etiologic studies.

BACKGROUND: Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children and adolescents aged <20 years; its etiology remains largely unknown. It is believed that embryonal (ERMS) and alveolar rhabdomyosarcoma (ARMS), the most common subtypes, arise through distinct biologic mechanisms. The authors of this report evaluated incidence and survival trends by RMS demographic subgroups to inform future etiologic hypotheses. METHODS: Incidence and survival trends in RMS among children and adolescents aged <20 years were analyzed using data from the Surveillance, Epidemiology, and End Results Program. Frequencies, age‐adjusted incidence and survival rates, and joinpoint regression results, including annual percentage change (APC) and 95% confidence interval (CI), were calculated. RESULTS: Between 1975 and 2005, the incidence of ERMS was stable, whereas a significant increase in the incidence of ARMS was observed (APC, 4.20%; 95%CI, 2.60%‐5.82%). This trend may have been attributable in part to shifts in diagnosis, because a significant negative trend in RMS, not otherwise specified was observed concurrently. A bimodal age peak for ERMS was observed, with the second, smaller peak in adolescence noted for males only; ARMS incidence did not vary by age or sex. Five‐year survival rates for RMS and ERMS increased during the period from 1976 to 1980 (52.7% and 60.9%, respectively) to the period from 1996 to 2000 (61.8% and 73.4%, respectively), whereas there was little improvement for ARMS (40.1% and 47.8%, respectively). CONCLUSIONS: Observed differences in incidence and survival for 2 major RMS subtypes across sex and age subgroups further supported the hypothesis that there are unique underlying etiologies for these tumors. Exploration of these differences presents an opportunity to increase current knowledge of RMS. Cancer 2009. © 2009 American Cancer Society.