A rise in the incidence of childhood cancer in the United States

Do pregnancy characteristics contribute to rising childhood cancer incidence rates in the United States?

BACKGROUND

Since 1975, childhood cancer incidence rates have gradually increased in the United States; however, few studies have conducted analyses across time to unpack this temporal rise. The aim of this study was to test the hypothesis that increasing cancer incidence rates are due to secular trends in pregnancy characteristics that are established risk factors for childhood cancer incidence including older maternal age, higher birthweight, and lower birth order. We also considered temporal trends in sociodemographic characteristics including race/ethnicity and poverty.

PROCEDURE

We conducted a time series county-level ecologic analysis using linked population-based data from Surveillance, Epidemiology, and End Results cancer registries (1975-2013), birth data from the National Center for Health Statistics (1970-2013), and sociodemographic data from the US Census (1970-2010). We estimated unadjusted and adjusted average annual percent changes (AAPCs) in incidence of combined (all diagnoses) and individual types of cancer among children, ages 0-4 years, from Poisson mixed models.

RESULTS

There was a statistically significant unadjusted temporal rise in incidence of combined childhood cancers (AAPC = 0.71%; 95% CI = 0.55-0.86), acute lymphoblastic leukemia (0.78%; 0.49-1.07), acute myeloid leukemia (1.86%; 1.13-2.59), central nervous system tumors (1.31%; 0.94-1.67), and hepatoblastoma (2.70%; 1.68-3.72). Adjustment for county-level maternal age reduced estimated AAPCs between 8% (hepatoblastoma) and 55% (combined). However, adjustment for other county characteristics did not attenuate AAPCs, and AAPCs remained significantly above 0% in models fully adjusted for county-level characteristics.

CONCLUSION

Although rising maternal age may account for some of the increase in childhood cancer incidence over time, other factors, not considered in this analysis, may also contribute to temporal trends.

Communication Issues Faced by Parents Who have a Child Diagnosed with Cancer

Twenty-nine parents of children who had been diagnosed with various cancers were interviewed through long, semistructured interviews conducted via telephone by a mother whose daughter once had cancer. Parents usually began their narratives of the defining moments in the months, weeks, or days prior to the diagnosis. The authors report on parents' views about one of the defining moments in the stories. At the first level, we call this “communication issues” and include the following topics: communication at diagnosis, contradictions and confusion, getting the “right” amount of information, good and poor communication, feeling listened to, and errors in medical information. At another level, the way that parents talk about communications issues reflects an underlying paradox that parents whose children have cancer face: They are and feel responsible for their children, and yet they often lack knowledge, authority, and power in their dealings with the health care system and its medical care providers.

Response to Critique by John Bukowski

A recent study documenting rising childhood cancer incidence in the United States was critiqued based on various methodological issues alleged to “cast doubt” on the findings. Many of the criticisms are not supported and are contradicted by empirical data, presented in this article. For example, the assertion that long-term incidence increases were due only to improved diagnostic techniques in 1983–1986 is not supported by available data on cancer incidence and supply of computerized scanning machines. Understanding the characteristics and causes of childhood cancer is a complex undertaking, and researchers should objectively consider multiple analytical methods.

Exposure Risks Among Children Undergoing Radiation Therapy: Considerations in the Era of Image Guided Radiation Therapy

Recent improvements in toxicity profiles of pediatric oncology patients are attributable, in part, to advances in the field of radiation oncology such as intensity modulated radiation (IMRT) and proton therapy (IMPT). While IMRT and IMPT deliver highly conformal dose to targeted volumes, they commonly demand the addition of 2- or 3-dimensional imaging for precise positioning--a technique known as image guided radiation therapy (IGRT). In this manuscript we address strategies to further minimize exposure risk in children by reducing effective IGRT dose. Portal X rays and cone beam computed tomography (CBCT) are commonly used to verify patient position during IGRT and, because their relative radiation exposure is far less than the radiation absorbed from therapeutic treatment beams, their sometimes significant contribution to cumulative risk can be easily overlooked. Optimizing the conformality of IMRT/IMPT while simultaneously ignoring IGRT dose may result in organs at risk being exposed to a greater proportion of radiation from IGRT than from therapeutic beams. Over a treatment course, cumulative central-axis CBCT effective dose can approach or supersede the amount of radiation absorbed from a single treatment fraction, a theoretical increase of 3% to 5% in mutagenic risk. In select scenarios, this may result in the underprediction of acute and late toxicity risk (such as azoospermia, ovarian dysfunction, or increased lifetime mutagenic risk) in radiation-sensitive organs and patients. Although dependent on variables such as patient age, gender, weight, body habitus, anatomic location, and dose-toxicity thresholds, modifying IGRT use and acquisition parameters such as frequency, imaging modality, beam energy, current, voltage, rotational degree, collimation, field size, reconstruction algorithm, and documentation can reduce exposure, avoid unnecessary toxicity, and achieve doses as low as reasonably achievable, promoting a culture and practice of "gentle IGRT."

Incidence of cancer in children residing in ten jurisdictions of the Mexican Republic: importance of the Cancer registry (a population-based study)

BACKGROUND

In 1996, Mexico started to register cases of childhood cancer. Here, we describe the incidence of cancer in children, residing in ten Mexican jurisdictions, who were treated by the Instituto Mexicano del Seguro Social (IMSS).

METHODS

New cases of childhood cancer, which were registered prospectively in nine principal Medical Centers of IMSS during the periods 1998-2000 (five jurisdictions) and 1996-2002 (five jurisdictions), were analyzed. Personnel were specifically trained to register, capture, and encode information. For each of these jurisdictions, the frequency, average annual age-standardized incidence (AAS) and average annual incidence per period by sex and, age, were calculated (rates per 1,000,000 children/years).

RESULTS

In total 2,615 new cases of cancer were registered, with the male/female ratio generally >1, but in some tumors there were more cases in females (retinoblastoma, germ cells tumors). The principal groups of neoplasms in seven jurisdictions were leukemias, central nervous system tumors (CNS tumors), and lymphomas, and the combined frequency for these three groups was 62.6 to 77.2%. Most frequently found (five jurisdictions) was the North American-European pattern (leukemias-CNS tumors-lymphomas). Eight jurisdictions had AAS within the range reported in the world literature. The highest incidence was found for children underless than five year of age. In eight jurisdictions, leukemia had high incidence (>50). The AAS of lymphomas was between 1.9 to 28.6. Chiapas and Guerrero had the highest AAS of CNS tumors (31.9 and 30.3, respectively). The frequency and incidence of neuroblastoma was low. Chiapas had the highest incidence of retinoblastoma (21.8). Germ-cell tumors had high incidence.

CONCLUSION

The North American-European pattern of cancers was the principal one found; the overall incidence was within the range reported worldwide. In general but particularly in two jurisdictions (Yucatán and Chiapas), it will be necessary to carry out studies concerning the causes of cancer in children. Due to the little that is known about the incidence of cancer in Mexican children, it will be necessary to develop a national program to establish a cancer registry for the whole of the country.

Advocacy: essential work for mothers of children living with cancer

This paper, based on focus group interviews with mothers whose children have had cancer, describes the advocacy work in which mothers engaged during the period of diagnosis and treatment. Among the mothers' manifold responsibilities, advocacy was one of the most compelling. It was described as if it was a taken-for-granted moral imperative. Some mothers said they felt that it was necessary because of (1) perceived errors during diagnosis or later during the process of treatment; (2) perceived understaffing; (3) advice given by other mothers or fathers; and (4) perceived lack of coordination and communication in the medical care system. Many coped with the need to advocate through educating themselves, by keeping extensive notes and journals and by talking to other parents about their experiences. The paper concludes with clinical practice implications and recommendations for policy consideration including acknowledgment of the significant role of optimal family cohesion for managing the stresses and strains of advocacy and other home health care work; appointment of parent-child advocates associated with hospitals that provide pediatric oncology care; establishment of in-service training and education for guardians and medical care teams regarding their mutual roles and responsibilities; as well as, the provision of guaranteed and paid parental leave policies for guardians whose children have a catastrophic or severe chronic medical condition.

Portrayal of childhood cancer in English language magazines in North America: 1970-2001

This article is a content and discourse analysis of the portrayal of childhood cancer in English language magazines in North America. In a unique specification of published research on the media portrayal of disease, magazines were divided into three market or audience groupings called (1) science, (2) news/special interest, and (3) other (women/teen/parenting/health). The predominate frames or discoursesin these three groups were compared and differences were found amongst them and discussed in the article. Considerable evidence suggests that people with cancer are stigmatized. In the analyzed media focused on children, those with cancer are highly idealized and stereotyped. On the one hand, this can be thought of as a very positive portrayal of children in this situation. Children are described as if they possess heroic and idealized character traits, appearances, social characteristics, and personalities. Possible links between this idealized, polarized, and biased portrayal of children with cancer and their documented experiences of stigma are discussed.

Whose power/authority/knowledge? Conundrums in the experiences of parents whose children have cancer

This paper is based on data collected from two different studies of parents (76 mothers and 14 fathers) whose children had been diagnosed with cancer. Although the goal of the first study, to describe parental experiences when their children have cancer, was different than the goal of the second study, to describe the home health care work done by parents whose children had cancer, the themes outlined here were reiterated from study to study. In both sets of data conflicts in the dynamics of power, authority and knowledge were pivotal to the dilemmas experienced by parents in their interactions with health care staff both during the time of diagnosis and later during the treatments when their children had cancer. The paper points to the significance of fundamental social processes such as power, authority and knowledge in understanding and ameliorating parental experiences when a child has cancer.

[Childhood cancer in the Autonomous Community of Cantabria in Spain (1995-2000)]

BACKGROUND

Since 1980, the epidemiology of childhood cancer in Spain has been registered through the National Registry of Childhood Cancer. However, this registry does not include patients from Autonomous Community of Cantabria because there is no reporting clinical center. The absence of data on childhood cancer in this region justifies this study.

OBJECTIVES

To analyze the clinical presentation, diagnostic delay and incidence of childhood cancer in Cantabria.

METHODS

We performed a retrospective analysis of 89 children (aged 0-15 years) diagnosed with cancer in Cantabria from 1995-2000.

RESULTS

The annual incidence of childhood cancer in the region was 198.1 cases per million inhabitants with a predominance of males (53.9 %) and children aged less than 5 years (46.1 %). The most frequent cancers were leukemia (32.6 %) and brain tumors (23.6 %). The most frequent signs and symptoms were fever (29.2 %) and decreased appetite or fatigue (19.1 %). The mean delay in diagnosis for all tumors was 5.99 weeks and delays were longest for brain tumors. There was a direct statistical relationship between non-specific clinical presentation and diagnostic delay. A total of 20.2 % of all patients received treatment outside Cantabria.

CONCLUSIONS

The incidence of all childhood cancers and especially that of neuroblastoma was higher in Cantabria than in other areas of Spain. In general, the major difficulties in the diagnosis of childhood cancer are its low incidence and non-specific presenting symptoms. Specialized pediatric oncology units near to patients' homes should be created to avoid problems due to treatment outside the area of residence.

Brain and other central nervous system tumors: rates, trends, and epidemiology

Reports that central nervous system (CNS) cancer rates are increasing have prompted debate on whether secular trends reflect environmental changes related to etiology or artifacts of case ascertainment. We present the most recent data from the National Cancer Institute's Surveillance, Epidemiology, and End Results program on incidence rates and trends of CNS malignancies, including primary CNS lymphomas, and on survival probability. We discuss the new 2000 standard for adjusting rates; underreporting of CNS tumor rates resulting from the exclusion of nonmalignancies in most cancer registries; and information on CNS tumor risk factors, including concerns related to nonionizing electromagnetic fields and wireless mobile telephones.

Strontium-90 in deciduous teeth as a factor in early childhood cancer

Strontium-90 concentrations in deciduous (baby) teeth of 515 children born mainly after the end of worldwide atmospheric nuclear bomb tests in 1980 are found to equal the concentrations in children born during atmospheric tests in the late 1950s. Recent Sr-90 concentrations in the New York-New Jersey-Long Island metropolitan area have exceeded the expected downward trend seen in both baby teeth and adult bone after the 1963 ban on atmospheric testing. Sharp rises and declines are also seen in Miami, Florida. In Suffolk County, Long Island, Sr-90 concentrations in baby teeth were significantly correlated with cancer incidence for children 0 to 4 years of age. A similar correlation of childhood malignancies with the rise and decline of Sr-90 in deciduous teeth occurred during the peak years of fallout in the 1950s and 1960s. Independent support for the relation between nuclear releases and childhood cancer is provided by a significant correlation with total alpha and beta activities in local surface water in Suffolk County. These results strongly support a major role of nuclear reactor releases in the increase of cancer and other immune-system-related disorders in young American children since the early 1980s.

Critical assessment of opposing views on trends in childhood cancer

Two articles reaching opposite conclusions on the current trends in childhood cancer have recently appeared in the literature. One concluded that pediatric cancers have increased dramatically, suggesting an effect from environmental hazards; the other concluded that rates for the major pediatric cancers have remained fairly stable, except for modest increases due to improvements in diagnosis or reporting. This review discusses the reasons for this discrepancy, including differences in the populations, age groups, and time periods analyzed. The arguments in favor of an increase are examined and shown to provide no convincing evidence that environmental pollutants have increased pediatric cancer rates over the past 20 to 30 years. Any suggested increase appears to be the result of non-causal factors, such as selective analysis and reporting, residual confounding by age, random variation, and stepwise improvements in diagnosis and classification.

The effect of chemotherapy on the growing skeleton

With the increasing use of high dose (poly)chemotherapy schedules in the treatment of childhood cancer it is particularly important to know the adverse effects of these treatments. Growth is a complex mechanism affected not only by chemotherapy but also by the malignancy itself as well as nutritional status, the use of corticosteroids and (cranial) radiation. In vitro and animal studies are often the most useful in determining the effect of a single chemotherapeutic agent on the growing skeleton. In vitro studies have shown doxorubicin, actinomycin D and cisplatin to have a direct effect on growth plate chondrocytes that in animals results in decreased growth and final height. Clinical studies with multiagent chemotherapy have demonstrated that antimetabolites decrease bone growth and final height. Childhood cancer survivors are at risk of a reduced bone mineral density, mainly due to methotrexate, ifosfamide and corticosteroids. This reduced bone mineral density persists into adult life and may increase bone fracture risk at an older age.

Effect of single chemotherapeutic agents on the growing skeleton of the rat

BACKGROUND

To establish the effect of chemotherapeutics on the growing skeleton, male Wistar rats were studied.

DESIGN

Between the ages of 4 and 13 weeks the rats were given i.v. doxorubicin 15 mg/m2 body surface area (BSA), methotrexate 60 mg/m2 BSA or cisplatin 7.5 mg/m2 BSA. For each group of drug-treated rats there was a diet-matched control group that was injected with a placebo only. Rats fed ad libitum served as the basic control group for length and weight growth. Body weight and tibial length were measured weekly. Kidney and liver weight were determined at the end of the study.

RESULTS

Weight gain and length growth were significantly decreased in the diet controlled groups (P < 0.05). Doxorubicin reduced length growth with 4.12 mm or 18% (P < 0.05). Methotrexate reduced length growth with 1.11 mm or 5% (P < 0.05). Length growth in the cisplatin treated rats did not differ from the diet controls.

CONCLUSIONS

Doxorubicin and methotrexate decrease length growth in the rat tibia by, respectively, 18% and 5%. Cisplatin does not affect length growth. The decrease in growth might be a direct effect of doxorubicin and methotrexate on the tibial growth plate and metaphysis, but may be more pronounced due to the malnutrition.

Strontium-90 in newborns and childhood disease

Radioactive strontium-90 concentrations in baby teeth obtained from Suffolk County, New York, rose steadily during the 1980s. Recent levels of strontium-90 are similar to those reported for babies born in the late 1950s-at the height of atmospheric nuclear weapons testing in Nevada. Strontium-90 concentrations increased concomitantly with increases in cancer incidence among Suffolk children under the age of 5 y, a result that mimicked parallel trends observed in the 1950s and early 1960s. Given that effects of strontium-90 on developing cells are most pronounced during the fetal and infant periods, escalating levels should be viewed as a factor in the recent decline in various child health status measures.