Pan Arab Journal of Oncology - Arab Medical Association Against ...

CANCER PREVENTION AND EARLY DETECTION IN CHILDREN
MALIGNANCIES
Reem Al Sudairy, MD
King Abdulaziz Medical City for National Guard, Riyadh, KSA
Corresponding Author: Reem Al Sudairy, MD
Department of Oncology (Mail Code 1777)
P.O. Box 22490, Riyadh 11426, Kingdom of Saudi Arabia
E-mail: sudairyr@ngha.med.sa
Abstract
Objectives: Cancer in children is rare disease. It accounts for about 1% of all
malignancies, and as a result, understanding of the factors causing childhood
cancer is less well defined compared to that for adults. Medical research has
contributed greatly to improved treatment outcome in childhood cancer, reaching
cure rates up to 80%. However, little progress has been made in prevention of
childhood cancer. This manuscript summarizes the early detection and prevention
guidelines for children.
Methods: Review of the literature and international pediatric oncology
recommendations about childhood cancer prevention and early detection are
reviewed and summarized.
Results: Genetic predisposition can cause up to 10% of all childhood malignancies.
This important risk factor will be discussed in details with emphasis on
recommendations for genetic testing and follow up of those children by the
primary care physicians.
Environmental / external factors in relation to childhood cancer will be also
reviewed with updated information on current research pertinent to this important
risk factor. Recommendations to pediatricians and primary care physicians
concerning early detection and prevention of childhood malignancies in at risk
population will be also discussed.
While there is still a knowledge gap in the field, there are certain clinical situation
where early detection and prevention will help in the control of childhood cancer.
Introduction
Cancer in children is rare and accounts for about 1% of all malignancies and as a
result the precise causes of childhood cancers are still insufficiently known, and they
are less well defined compared to that for adults. Childhood Cancers is typically
of different variety from those observed in adults. The carcinogenic process in
children is much shorter in time. In children cancers are mainly mesenchymal /
neural in origin while in adults they are mainly epithelial and in internal organs
and have a strong and proven link to environmental factors.
Incidence
Approximately 149 of every 1 million children under the age of 20 years are
diagnosed with cancer each year in the United States. Acute leukemia accounts
for the greatest proportion of new cancer cases (25-30%) followed by brain tumors
(20%) and lymphomas (15%). (1)
According to the Saudi Cancer Registry 2004 statistics, the total incident cases
reported among children (0-14 years) were 713 which represent 7.6 % of the
total number of cancers in Saudi Arabia. Of all the cases reported, there were
584 Saudis. (2)
Although the incidence of pediatric cancer is low, its significance is of great
importance. In KSA in 2007 approximately 40% of the Saudi population was under
15 years which put a large number of the population at risk of childhood cancer.
Childhood Cancer Symptoms
The symptoms of childhood cancer depend on the site and the extent of the tumor.
Leukemia can cause anemia, bleeding, fever, bone pain and lymph nodes, spleen,
liver enlargement. Most of other tumors produce symptoms related to their position
either in the form of a lump or because it impairs the function of one or more organs.
Most of children with cancer are treated at pediatric cancer centers per national
clinical protocols. Surgery, chemotherapy, radiotherapy are the mainstay of
treatment for most childhood cancers. Bone marrow and peripheral stem cell
transplantation is another important modality of therapy in some cases.
Outcome
Although cancer still represents the second most common cause of death in children
(following accidents), the survival rate from children cancer have improved
substantially in the last 30 years and had risen to over 75% due to improvement in
treatment modalities. There is a relative greater improvement in the young age group
(under 15 years) in comparison to older children (15-19 years of age). Although
disease biology may play a role in this difference in outcome, failure to treat
older children on national protocols plays a major role in their inferior outcome.
Risk Factors
The precise causes of many childhood cancers are still not well understood but
they are assumed to be multi-factorial. The two most important risk factors are:
1. Genetic predisposition.
2. Environmental factors (Inutero and during early childhood).
Genetic pre-disposition to Cancer
A large number of predisposing syndromes exist and account for up to 10% of
all childhood malignancies. Most syndromes are associated with a germ line
mutation in a single gene (e.g. RB1) however; in some syndromes (e.g. Wilm’s
Tumor) several genetic loci have been involved. Polymorphism of certain genes
loci have been shown to play a role in cancer development. (3)
Table 1 shows the genetic conditions predisposing to cancer in children. It is
the responsibility of the pediatricians/family physician’s to be able to recognize
clinically cancer-predisposing syndromes, and should strongly suspect the presence
of cancer-predisposing condition from the family history (earlier age of cancer
onset, bilateral or multifocal tumors, and multiple primary malignancies of
different types in the same individuals). The presence of certain physical signs in
parent should also alert physicians, like café-au-lait spots and axillary freckling
(Neurofibromatosis type1). All at risk children should be referred to a trained
genetic counselor and should be followed up regularly by their pediatrician/
family physician.
www.amaac.info Pan Arab Journal of Oncology | vol 3; issue 1 | March 10 < 79