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2 Acute Lymphoblastic Leukemia

15

 

 

2.4.7Cell Kinetics

See Chap. 1.

Leukemic blast cells are characterized by an arrest of maturation at a certain stage of proliferation and by increased cell-survival mechanisms. Physiologically, this results in a progressive accumulation of leukemic cells and replacement of normal cells in the bone marrow, lymph nodes, and infiltration of other organs

With the labeling index (LI), the rate of cells in DNA synthesis is measured 1 h after injection of tritium–thymidine:

LI of leukemic lymphoblasts is 15–35%

LI of leukemic myeloblasts is approx. 4–15%, which is low in comparison with normal myeloblasts (LI = 40–70%). This means that the cell cycle duration for leukemic myeloblasts is 45–48 h in comparison with 15 h of normal myeloblasts

2.5Prognostic Factors of All

Prognostic factorsa

Favorable

Unfavorable

WBC

<10 × 109/l

>50 × 109/l (ca. 20%)

Age (years)

2–7

<2 and >10 (especially in infants)

Gender

Female

Male

Response to steroid treatment

+

Response to treatment

<4 weeks

>4 weeks

MRD

Negative day 15

Positive day 33+

Time of relapse after treatment ends

>6 months

<6 months

Surface markers

Precursor-B-ALL T-/B-ALL

Cytogenetic characterization (DI)

Hyperdiploid

Hypodiploid

Structure

 

11q23/MLL-ALL gene

 

 

rearrangement

 

 

Ph+

FAB

L1

L2/L3

Mediastinal enlargement

(+)

Visceromegaly

+ to ++

+++

LDH

Moderate

High

Racial groups

White

Blackb

aIn order of importance

 

 

bSmall difference in some studies

 

 

The risk of relapse depends on the initial corticosteroid response, the molecular genetic results, and the minimal residual disease (see page 9) early during treatment

MRD results may determine the stratification of treatment according to standard risk (40% of ALL), intermediate risk (45%), or high risk (ca15% of ALL)

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