Malignant disease

Published on 21/03/2015 by admin

Filed under Pediatrics

Last modified 21/03/2015

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Malignant disease

Cancer in children is not common.

The types of disease seen (Fig. 21.1) are very different from those in adults, where carcinomas of the lung, breast, gut and skin predominate. The age at presentation varies with the different types of disease:

Despite significant improvements in survival over the last four decades (Fig. 21.2), cancer is the commonest disease causing death in childhood (beyond the neonatal period). Overall, the 5-year survival of children with all forms of cancer is about 75%, most of whom can be considered cured, although cure rates vary considerably for different diagnoses. This improved life expectancy can be attributed mainly to the introduction of multi-agent chemotherapy, supportive care and specialist multidisciplinary management. However, for some children, the price of survival is long-term medical or psychosocial difficulties.

Aetiology

In most cases, the precise aetiology of childhood cancer is unclear, but it is likely to involve an interaction between environmental factors (e.g. viral infection) and host genetic susceptibility. In fact, there are very few established environmental risk factors, and although cancer occurs as a result of mutations in cellular growth controlling genes, which are usually sporadic but may be inherited, in most cases a specific gene mutation is unknown. One example of an inherited cancer is bilateral retinoblastoma, which is associated with a mutation within the RB gene located on chromosome 13. There is a wide range of syndromes associated with an increased risk of cancer in childhood, e.g. associations exist between Down syndrome and leukaemia, and neurofibromatosis and glioma. In time, the further identification of biological characteristics of specific tumour cells may also help elucidate the basic pathogenetic mechanisms behind their origin.

Investigations

Initial symptoms can be very non-specific and this can often lead to significant delays in diagnosis. Once a diagnosis of malignancy is suspected, the child should be referred to a specialist centre for further investigation.

Management

Once malignancy has been diagnosed, the parents and child need to be seen and the diagnosis explained to them in a realistic, yet positive way. Detailed investigation to define the extent of the disease (staging) is paramount to planning treatment. Children are usually treated as part of national and international collaborative studies that offer consistency in care and have contributed to improvements in outcome.

In the UK, children with cancer are initially investigated and treated in specialist centres where experienced multidisciplinary teams can provide the intensive medical and psychosocial support required. Subsequent management is often shared between the specialist centre, referral hospital and local services within the community, to provide the optimum care with the least disruption to the family.

Treatment

Treatment may involve chemotherapy, surgery or radiotherapy, alone or in combination.

Surgery

Initial surgery is frequently restricted to biopsy to establish the diagnosis, and more extensive operations are usually undertaken to remove residual tumour after chemotherapy and/or radiotherapy.

High-dose therapy with bone marrow rescue

The limitation of both chemotherapy and radiotherapy is the risk of irreversible damage to normal tissues, particularly bone marrow. Transplantation of bone marrow stem cells can be used as a strategy to intensify the treatment of patients with the administration of potentially lethal doses of chemotherapy and/or radiation. The source of the marrow stem cells may be allogeneic (from a compatible donor) or autologous (from the patient him/herself, harvested beforehand, while the marrow is uninvolved or in remission). Allogeneic transplantation is principally used in the management of high-risk or relapsed leukaemia and autologous stem cell support is used most commonly in the treatment of children with solid tumours whose prognosis is poor using conventional chemotherapy, e.g. advanced neuroblastoma.

Supportive care and side-effects of treatment

Cancer treatment produces frequent, predictable and often severe multisystem side-effects (Fig. 21.3). Supportive care is an important part of management and improvements in this aspect of cancer care have contributed to the increasing survival rates.

Infection from immunosuppression

Due to both treatment (chemotherapy or wide-field radiation) and underlying disease, children with cancer are immunocompromised and at risk of serious infection. Children with fever and neutropenia must be admitted promptly to hospital for cultures and treatment with broad-spectrum antibiotics. Some important opportunistic infections associated with therapy for cancer include Pneumocystis jiroveci (carinii) pneumonia (especially in children with leukaemia), disseminated fungal infection (e.g. aspergillosis and candidiasis) and coagulase-negative staphylococcal infections of central venous catheters.

Most common viral infections are no worse in children with cancer than in other children, but measles and varicella zoster (chickenpox) may have atypical presentation and can be life-threatening. If non-immune, immunocompromised children are at risk from contact with measles or varicella, some protection can be afforded by prompt administration of immunoglobulin or zoster immune globulin. Aciclovir is used to treat established varicella infection, but no treatment is available for measles. During chemotherapy and from 6 months to a year subsequently, the use of live vaccines is contraindicated due to depressed immunity. After this period, re-immunisation against common childhood infections is recommended.

Other supportive care issues

Fertility preservation

Some patients may be at risk of infertility as a result of their cancer treatment. Appropriate fertility preservation techniques may involve surgically moving a testis or ovary out of the radiotherapy field; sperm banking (which should be offered to boys mature enough to achieve this); and consideration of newer techniques such as cryopreservation of ovarian cortical tissue, although the long-term efficacy of this is still uncertain.

Psychosocial support

The diagnosis of a potentially fatal illness has an enormous and long-lasting impact on the whole family. They need the opportunity to discuss the implications of the diagnosis and its treatment and their anxiety, fear, guilt and sadness. Most will benefit from the counselling and practical support provided by health professionals. Help with practical issues, including transport, finances, accommodation and care of siblings, is an early priority. The provision of detailed written material for parents will help them understand their child’s disease and treatment. The children themselves, and their siblings, need an age-appropriate explanation of the disease. Once treatment is established and the disease appears to be under control, families should be encouraged to return to as normal a lifestyle as possible. Early return to school is important and children with cancer should not be allowed to under-achieve the expectations previously held for them. It is easy to underestimate the severe stress that persists within families in relation to the uncertainty of the long-term outcome. This often manifests itself as marital problems in parents and behavioural difficulties in both the child and siblings.