- Citado por SciELO
versión impresa ISSN 1698-4447
Med. oral patol. oral cir. bucal (Ed.impr.) v.10 n.1 Valencia ene.-feb. 2005
CABRERIZO-MERINO MC, OÑATE-SÁNCHEZ RE. SOME ODONTOSTOMATOLOGICAL ASPECTS IN CHILDHOOD ONCOLOGY. MED ORAL PATOL ORAL CIR BUCAL 2005;10:41-7.
Childhood neoplasias have become increasingly important in recent
years in the ambit of paediatric medicine. This phenomenon has been
accompanied by a spectacular improvement in the treatment of
childhood cancer, long-term survival rates reaching 90% in the case
of some tumours. A corollary of this success is the obligation to
provide new and improved medical assistance both as regards the
possible prevention of any alterations and, if possible, the
avoidance of complications derived from the neoplasm itself and its treatment.
Among possible secondary effects are oral manifestations of a chronic or acute nature, which may cause great discomfort, act as foci of sytemic infections or have long-term after effects, all of which will depend on the exact moment of the childs development that treatment is undertaken.
The incidence and severity of most oral complications is associated with pre-existent factors, such as caries, gingivitis or generally poor hygiene, which strongly affect the beginning, increase and persistence of the same. It is to be decried that a problem in the buccal cavity is allowed to develop, which a simple preventative measure, simple hygiene or dental conservation treatment could prevent or reduce.
Key words: Childhood cancer, oral pathology, buccodental prevention.
CONCEPT AND EPIDEMIOLOGY
Malignant tumours diagnosed in children under the age of fifteen are considered as cases of childhood cancer, according to the ninth revision of the International Classification of Diseases (ICD-9).
Although childhood cancer has a low incidence, both among paediatric illnesses and among neoplastic illnesses of the population as a whole, it is the second most common cause of death (after accidents) in children older than one year (1). Worldwide, the annual incidence is 120-150 new cases per million children aged less than fifteen, although the exact figure varies according to age, sex, race and geographical location. Recent years, however, have seen an increase in the number of cases recorded but an overall decrease in morbimortality, as a consequence of the diagnostic and therapeutic advances made (2-4).
In Spain, overall survival in the last five years, as recorded in the National Register of Childhood Tumours, runs at 71%, passing from a death rate of 8/100,000 in 1950 to the present figure of 4/100,000 (4, 5).
The most frequent neoplasias in children are leukaemias, which represent one third of the total (of which more than 80% are acute lymphoblastic leukaemias) and as much as one half of all childhood cancers if leukaemias and lymphomas are considered jointly.
In Europe, North America, Australia and Japan, tumours of the central nervous system are second in order of frequency, representing 18-20%. Of importance in this respect are brain tumours and spinal medulla tumours, such as astrocytomas and meduloblastomas.
Lymphomas represent 10% of the total, most being non-Hodgkins lymphomas.
The remaining childhood neoplasias are: neuroblastomas (8%), Wilms tumour (7%), of soft tissue sarcomas (6%), bone tumours (5%), retinoblastomas (3%), hepatoblastomas (2-3%) and germinal cell tumours, which, although the least frequent, are usually confined to chidhood (6-8).
CHARACTERISTICS OF CHILDHOOD CANCER
The general pattern of cancer in children is very different from that observed in adults. In the first place, a child affected by a malignant tumour has a greater potential of growth and development than an adult, and so the childs normal evolution will be seriously affected by the disease and its treatment.
While carcinomas are more common in adults, children tend to be more susceptible to sarcomas and, especially, tumours with histological aspects reminiscent of foetal development, denominated embryonal and which are frequently strongly related with congenital malformations.
The so-called solid tumours are typical of infancy, appearing in the first five years of life; among the most important are neuroblastomas, Wilms tumour, retinoblastomas and Ewings sarcoma (6, 8).
Organs with exposed surfaces such as the skin, the intestine and lung, and those under endocrine control, such as the breast or prostate, tend not to be affected.
Cancers in children are generally anatomically deep; normally, they do not affect the epithelia, or provoke surface haemorrhaging or the exfoliation of tumoral cells (7). Consequently, the early detection techniques that are of great use in some adult cancers are of little use in children and diagnosis tends to be accidental, meaning that, in many cases, the neoplastic disease is found at a relatively late stage of development (4, 7).
Clinical manifestations are usually unspecific and include a poor general state of health, fever, weight loss etc., making diagnosis very difficult as the symptoms overlap those of common childhood illnesses: infectious processes of the upper respiratory tracts, tumescence of the lymphatic ganglia or articulatory pains associated with growth (4, 9). On other occasions, the symptoms may be similar to those of rheumatic fever or Guillain-Barrés syndrome. Whatever the case, correct diagnosis may be delayed and general or specific treatment of the suspected process may be have already begun.
Biologically, childhood tumours present a cell kinetics characterised by rapid development with a very high fraction of cell growth, enabling them to invade many tissues and organs in a diffuse way and in the very early stages of disease. This is always an unpleasant surprise to the parents and, indeed, to the doctor, who, perhaps only a few days before the correct diagnosis, had noticed nothing untoward. However, on the bright side, is the fact that the childs response to therapy is frequently much more effective than the adults (4).
ORAL PATHOLOGY IN CHILDHOOD CANCER
The advances made in the treatment of childhood cancer in recent decades mean that this population needs greater medical attention at all levels to prevent to the greatest extent possible, complications arising from the neoplasia itself and from the resulting treatment, including oral alterations. (10).
Although mouth cancer is rare in infancy, it must be remembered that 53% of malign tumours in children are of the head and neck, including the CNS and lymphoid organs (nasopharyngeal, rhabdomyosarcoma, fibrosarcoma, olfactory asthesio-neuroblastma, among others) (11). Despite the fact, therefore, that the cancers are located away from the immediate maxillofacial area, chemotherapy is an aggressive and systemic treatment that affects the whole organism, especially when still growing organism.
The relevant literature points to a greater incidence and gravity of acute oral pathologies, such as mucositis, buccal ulcerations, herpetic infections, candidiasis, haemorrhages or cheilitis, at the paediatric age (10, 12-19), due to accelerated cell kinetics. These lesions appear in phases of aplasia, and are more frequent in situation where caries, gingivitis and poor oral hygiene are already a problem, according to some authors, who mention figures ranging from 8% (13) to 35% (12).
Several, sometimes interrelated, chronic oral manifestations may appear, unlike in adult patients since the dental and facial structures are still developing. Bone anomalies, dental agenesia, microdontics, tooth enamel defects may be present to a greater extent than in a healthy population; this is especially true for dental malformations at root level, crowns and the presence of rudimentary teeth. These are influenced by the type of treatment undertaken (chemotherapy and/or radiotherapy in the maxillofacial area) and the age of the patient (therapy in the first years of life). A correlation between the moment treatment is started and the beginning of mineralisation in the dental pieces affected has been observed (10, 16).
On the other hand, most studies of this population have demonstrated that caries, gingival pathologies and malocclusions increase with age, as they do in the corresponding healthy population (10, 13). Therefore, individual prevention programmes and the early diagnosis and treatment of buccodental anomalies in affected individuals are essential to minimise oral repercussions of oncological treatment and to improve buccodental health.
This should be started as early as possible but, in any case, well before oncological treatment begins, during the intervals between treatments, and after treatment has ceased. The first step is a thorough medical check-up and complete buccodental exploration. For the correct oral diagnosis, a panoramic X-ray of the mouth, including bitewings and periapical films, and any other complementary explorations considered necessary should be made. Treatment should start early, eliminating potential septic and iatrogenic foci, such as poor restorations, dental fractures and orthopaedic apparatology.
The preventative programme should attempt to motivate the child and parents concerning the importance of oral hygiene, provide advice concerning diet, control bacterial plaque and, when necessary, include the application of fluoride and sealants to cavities and fissures. Periodical follow-up visits should be arranged.
Most studies related with childhood oncology suggest that five days after beginning cranial or cervical chemotherapy and/or radiotherapy and during the following two weeks (coinciding with the highest risk of neutropenia and alterations in the oral mucosa), the patient should use a mouthwash of saline bicarbonate solution (0.9% sodium chloride and 5% sodium bicarbonate) after each meal. If this is not possible, a gentle cleaning of the bucccal cavity with gauze or sponge impregnated with the same solution is recommended.
At the same time, mouthwashes of 0.12% chlorhexidine (alcohol-free) should be prescribed to children of 5-6 years. This should be carried out twice a day (after breakfast and the last meal at night), taking care not to swallow the product. In children of a lower age or those unable to use a mouthwash, a chlorhexidine spray (four applications, one for each quadrant of the mouth) or topical applications with a chlorhexidine bioadhesive gel, or swab, gauze or sponge impregnated with chlorhexidine is an alternative.
Sodium fluoride at 0.05% should be administered one a day (after the midday meal) as a mouthwash, which should be kept in the mouth for a sufficient time but not swallowed. Food or drink should not be consumed for a time afterwards, and the mouthwash should not coincide with another of chlorhexidine. Children less than 4-5 should be given sodium fluoride orally as one tablet of 0.25 mg every 24 hours or five drops per day. Care should be taken that this type of administration does not coincide with the ingestion of milk or dairy products. Topical application with a swab, gauze or sponge impregnated with sodium fluoride is an alternative.
Bacterial plaque should be controlled by brushing or by calculus removal, while therapy is being applied, during intervals in the same and even afterwards until the illness remits. Adult supervision is recommendable. As regards brushing, a toothbrush with a small head and soft or very soft bristles should be used at least twice a day, with special attention being paid to the chewing area and the dento-gingival margin, and using a fluoride toothpaste. Care should be taken that the children do not swallow the toothpaste. Even in the presence of bleeding, brushing should not be neglected as this will only aggravate the gingival situation. In cases of thrombocytopenia and/or neutropenia, with ulcerous manifestations, sponge or cotton wool impregnated with chlorhexidine can be used.
Foods rich in refined sugars of a doughy nature should be avoided, especially between meals. The child should be well hydrated, avoiding dryness of the mouth. Lip protectors can be used to keep the lips moist.
In the case of mucositis or mouth ulcers involving considerable pain, specific treatment (with antihistaminic agents, lidocaine, sucralfate) can be applied following a hospital protocol, making sure that the above-described oral hygiene practices are not abandoned.
If despite the antifungal action of chlorhexidine, signs of oral candidiasis appear, a solution of nistatine or miconazal gel can be applied, avoiding its use at the same time as chlorhexidine.
If radiotherapy is used in the area of the mouth, leaded or resin teeth protectors of sufficient thickness to prevent the passage of radiation should be used from the outset. The prevention of osteoradionecrosis should always be kept in mind, avoiding traumatisms, infections and tooth extraction, although it has not been described in children (20).
If odontostomatological actions cause bleeding or septicaemia, antibiotics should be prescribed during several days. Possible drugs prescribed by the child oncologist should be borne in mind to avoid possible interactions since curative or prophylactic antibiotherapy frequently involves penicillin (daily) or trimethoprim-sulfamethoxazole (alternate days) etc.
Given the age of the patients, it is frequent to use permanent intravenous access both for administering prolonged treatment and for nutritive and hydroelectrolytic support. At present, the preferred way is to implant capsules (Port-A-Cath® or Implantofix®) subcutaneously at thorax level, connected to a silicone catheter, whose distal end is situated in the upper vena cava. Access to the system is through a sealed silicone disc fitted to the upper end of the capsule (7). If such a device is in use, antibiotic prophylaxis before treatment is necessary, as recommended by the American Association of Cardiology in 1997 (21), and the drugs prescribed should be chosen accordingly if others were being used previously. Whatever the case, it is clear that there should be constant liaison between the dental team and the Paediatric Oncology Unit to plan treatment.
Although oral complications can increasingly be resolved by pharmacological and non-pharmacological means, such as cryotherapy, vitamins E and A, laser or tobramycin therapy, insufficient emphasis has been put on assessing the efficacy of buccodental prevention protocols, which may serve as a guideline for dentists before, during and after oncological treatment (22).
Paediatric oncological studies, such as those of Levy-Polack et al. (18), Rojas and Morales et al. (22) and Cheng et al. (23), demonstrate the importance of such programmes for diminishing the occurrence and severity of oral alterations in children, based on the mechanical control of plaque, a controlled diet and the use of substances such as fluoride, saline bicarbonate solutions or chlorhexidine (18, 19, 22, 24).
López et al. (25) observed a clear relation between the degree of gingival inflammation and the degree of mucositis recorded, noting the high number of occasions when an accumulation of bacterial plaque caused gingival inflammation and, as a consequence, bleeding. Despite the fact that some authors recommend not brushing in the case of intraoral bleeding, present day wisdom suggest brushing above 20,000 platelets/mm3 and 500 leukocytes/mm3, although protocols must be individualised for each patient and special oral hygiene measures should be established.
It is important that the oncological child be seen by the Preventative Odontological Unit (or equivalent) corresponding to his/her local health centre in order to carry out an oral examination, which will indicate the need for any special treatment and follow-up examinations, always in close contact with the hospital Paediatric Oncological Unit.
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