Fatores de prognóstico na leucemia linfoblástica aguda pediátrica

Abstract

A leucemia linfoblástica aguda é o cancro mais frequente na idade pediátrica. Apesar da ampla heterogeneidade clínica e biológica, a estratificação dos doentes em grupos de risco com base em fatores de prognóstico e o ajuste do tratamento a esse risco permitiu alcançar uma taxa de sobrevivência global superior a 90%. Os principais fatores de prognóstico utilizados nesta estratificação incluem características clínicas do doente (como a idade e a contagem inicial de leucócitos), características dos blastos (imunofenótipo, alterações cromossómicas, como translocações e aneuploidias, e genéticas) e resposta precoce ao tratamento, determinada sobretudo pela quantificação da doença residual mínima. Após a recidiva, os principais fatores de prognóstico são: a duração da primeira remissão, o local de recidiva e o imunofenótipo dos blastos. Esta estratificação permite a instituição de um tratamento mais adaptado e eficaz, intensificando ou atenuando a terapêutica dos doentes de alto e baixo risco, respetivamente. No entanto, um número significativo de doentes sofre recidiva e muitos destes acabam por falecer. Assim, torna-se evidente a necessidade de os categorizar tendo em consideração novos fatores de prognóstico, clínicos e citogenéticos, para um tratamento ainda mais personalizado e uma maior taxa de sobrevivência. Com o avanço da ciência, foram descobertos novos biomarcadores potencialmente úteis na previsão da evolução da doença. Contudo, a relevância prognóstica de muitos deles ainda está por definir.

Acute lymphoblastic leukemia is the most common cancer in pediatric age. Despite the wide clinical and biological heterogeneity, the stratification of patients into risk groups based on prognostic factors and the adjustment of treatment to that risk allowed an achievement of overall survival rate of over 90%. The main prognostic factors used in this stratification include the patient's clinical characteristics (such as age and initial leukocyte count), characteristics of the blasts (immunophenotype, chromosomal changes, such as translocations and aneuploidies, and genetic) and early response to treatment, determined mainly by quantification of minimal residual disease. After recurrence, the main prognostic factors are: the duration of the first remission, the site of recurrence and the immunophenotype of blasts. This stratification allows the institution of a more adapted and effective treatment, intensifying or attenuating the therapy in high and low risk patients, respectively. However, a significant number of patients relapse and many of these ends up dying. Thus, it becomes evident the need to categorize them taking into account new prognostic factors, clinical and cytogenetic, for an even more personalized treatment and a higher survival rate. With the advancement of science, new biomarkers potentially useful in predicting the evolution of the disease were discovered. However, the prognostic relevance of many of them is still to be defined. Acute lymphoblastic leukemia is the most common cancer in pediatric age. Despite the wide clinical and biological heterogeneity, the stratification of patients into risk groups based on prognostic factors and the adjustment of treatment to that risk allowed an achievement of overall survival rate of over 90%. The main prognostic factors used in this stratification include the patient's clinical characteristics (such as age and initial leukocyte count), characteristics of the blasts (immunophenotype, chromosomal changes, such as translocations and aneuploidies, and genetic) and early response to treatment, determined mainly by quantification of minimal residual disease. After recurrence, the main prognostic factors are: the duration of the first remission, the site of recurrence and the immunophenotype of blasts. This stratification allows the institution of a more adapted and effective treatment, intensifying or attenuating the therapy in high and low risk patients, respectively. However, a significant number of patients relapse and many of these ends up dying. Thus, it becomes evident the need to categorize them taking into account new prognostic factors, clinical and cytogenetic, for an even more personalized treatment and a higher survival rate. With the advancement of science, new biomarkers potentially useful in predicting the evolution of the disease were discovered. However, the prognostic relevance of many of them is still to be defined.