Pattern of leukemias : a ten-year incidence study of 242 cases.GG D'Costa, HM Siddiqui, RM Pradhan, SS Gupte
This paper presents an analysis of data collected from 242 cases of acute and chronic leukemia observed during a 10-year period. The incidence of childhood leukemia was 26.45%. In the present series, it was 35.95% for ALL, 21.9% AML, 38.4% CML and 2.89% CLL. The incidences of ALL and CML were found comparable to other series from Bombay. The geographical variations in the pattern of leukemias as observed in India are discussed.
Keywords: Adult, Aged, Aged, 80 and over, Child, Child, Preschool, Female, Human, Incidence, India, epidemiology,Infant, Leukemia, epidemiology,Male, Middle Age, Retrospective Studies,
The incidence of different types of leukemia varies with the age in different parts of India. The data of cases diagnosed as leukemia, during a span of 10 years (1975 to 1984) were analysed to evaluate its incidence at our set-up and to compare these observations with those reported by other workers from India and abroad.
The cases of acute and chronic leukemia registered in the Haematology laboratory of J. J. Hospital and the Department of Pathology, Grant Medical College were recruited in the study. Retrospective analysis with respect to diagnostic type, demographic data (age, sex), symptoms and cellular pattern of blood smear, was carried out from 1975 to 1977, while from 1978 onwards a prospective study for the same was undertaken.
F.A.B. (French, American and British) classification14 was used for acute myelogenous leukemia (AML), which subdivides the entity into M1 to M6, and terms acute megakaryoblastic leukemia as M7. Acute lymphoblastic leukemia (ALL) was subdivided into three subtypes viz. L1, L2 and L3.
For all the acute leukemic cases, peroxidase and PAS stain were used for diagnosis. Whenever necessary, special stains for acid phosphatase, TRAP (Tartrate resistant acid phosphatase) and LAP (Leucocyte and phosphatase) scores were used; Ph (Philadelphia chromosome) study and bone marrow trephine biopsy were employed to aid the typing.
Out of total 242 cases, 64 cases (26.45%) were children and 178 were adults (73.55%) [Table - 1]. Among the children, 41 were males and 23 were females (M:F ratio of 1.7: 1). In the adults, 136 were males and 42 females and thus the ratio was 3.2: l. The overall M:F ratio was 2.7 :1.
The youngest patient of the series was a female aged 3 weeks. In children, the majority of cases of ALL (39/46) were nearly equality distributed in the 3 age groups viz. 0-3 yr, 4-6 yr and 7-9 yr. Six patients with AML, were diagnosed in late childhood (10-12 yr). Chronic leukemia was rare in children and all the 6 cases of chronic myelogenous leukemia (CML) were seen in late childhood.
In adults, the age distribution was as follows: 84 cases in the 3rd and 4th decades of life, 82 cases in the 5th and 6th decades and only 12 from the 7th and 8th decades. The age of the oldest patient diagnosed as CML was 80 years.
As seen from[Table - 1], of the 242 cases, 140 were of acute leukemia and the rest (102 cases) of chronic leukemia. In children the incidence of acute leukemia was more (23.96%) compared to that of chronic (2.47%). The incidence of ALL was found to be higher than that of AML. Of the total 93 cases of CML, diagnosed in the series, only 6 were from the paediatric group. In adults the incidence of chronic leukemia was 39.66% while that of acute leukemia was 33.88%. In this age group, frequency of ALL and AML was equal, 41 cases each. Of the total 96 cases of chronic leukemia reported in adults, 87 were of CML, 7 were CLI. (chronic lymphocytic leukemia) and 2 of HCL (Hairy cell leukemia).
According to the F.A.B. classification of AML, there were 38 cases of M1 and M2, 3 cases of M3, 11 of M4 and only 1 case of M6. There was no case belonging to type M5, or M7;. In ALL, L1 and L2 were equally frequent, with no case of L3.
There were 7 cases of rare leukemias i.e. 3 cases of AML (M3), one case of type M6, 2 cases of HCL and 1 case of perinatal leukemia. Of the 3 cases belonging to M3, 2 were males with one female aged 32, 28 and 17 year, respectively. The M,; AML (erythroleukemia) was diagnosed in a male, aged 52 years. Both the cases of HCL were males, aged 40 and 55 year respectively. Hairy cells were seen in the smears of blood and bone marrow. Both had subleukemic blood counts with neutropenia, thrombocytopenia and, relative and absolute lymphocytosis. TRAP was positive in both the cases. One case had a splenectomy and was symptom-free for 6 months. The second had megaloblastic dyserythropoesis refractory to B12 and folic acid therapy. The case of perinatal leukemia was the youngest patient of this series (24 days old), who presented with erythematous, papular skin lesions on the 5th day of the birth and was diagnosed clinically as congenital syphilis. Examination of the blood, bone marrow and skin lesion biopsy revealed AML with myelomonocytic features (M4) and Auer rods More Details. This patient did not survive and on autopsy AML infiltrates were observed in the liver and the other organs. Thus, this case of perinatal leukemia presented as congenital leukemia cutis (CLC).
On analysis of symptoms and signs, it was observed that fever was the commonest symptom, followed by weakness, bleeding and bone pain, the latter two being frequent in ALL. Gum hypertrophy was present only in AML. The incidence of hepatomegaly was equal in ALL and CML, less so in AML. Splenomegaly was common mainly in CML and CLL, followed by ALL.
Severe anaemia (Hb less than 5 gm%) was found in 25% cases, while others had moderate anaemia (Hb 5-10 gm%). The incidence of both, moderate and severe anaemia was equal in ALL (76/87) and AML (45/53). Majority of the cases of ALL and AML had more than 30% of blast cells in their bone marrow. Subleukemic leukemia i.e. bone marrow showing more than 30% blast cells and total leucocyte count less than 12,000/mm was observed in 53 of 242 cases, accounting. for 21.9% of all cases of leukemia and 36.42% of acute leukemia. Of these, 25 were children and 28 adults. In children, 20 were of ALL. and 5 of AML. The incidence of subleukemic leukemia -was equal for AML and ALL detected in adults (13 cases each). On the other hand, total leucocyte count of more than 100,000/mm3 was a more frequent finding in CML (2/3rd cases) and was also seen in about ¼th cases of ALL.
Majority of cases of CML and CLL were characterized by less than 5% of blast cells in the peripheral blood. Seventy three cases of acute leukemia had upto 50% blast cells, while the rest had more than 50% blast cells in the peripheral blood. Low counts of platelets were observed in ALL (4/5th of cases), followed by AML (3/4ths) and CLL (2/3rds).
The frequency of all types of leukemia as reported from different parts of India is depicted in[Table - 2]. Compared to another series from Bombay, by Advani et al, we have fewer cases of CLL and more cases of AML. This compilation reveals geographic variation in frequency of leukemia. ALL is reported to be the most frequent in the South, and intermediate in the West and central India. In an another series from South, reported by Prakash et al the incidence was 35%, which is comparable to those reported by Advani et al, Pradhan et al and also observed by us in the present series. Interestingly, the incidence of ALL is lesser in East India as well as Northern areas., On the other hand, frequency of CML is maximum in North 45.4% and 57.7% as reported by Rani et al and Sakhuja et al. The incidence was intermediate in the East, West and Centre,, and in one series from South. It was observed to be the lowest in the series of Verghese et al, from Kerala.
The pattern of leukemias in children as reported by various workers is shown in[Table - 3]. In children also, ALL is less frequent in the North. Compared to the incidences in the South the frequency of ALL is lower in Central India. AML shows a reverse trend, except for the series reported by Rajarajeswari and Viswanathan, from Thanjavur. M type of AML is reported only from Delhi. We have not encountered M" in our series of 64 cases, as is the case with other workers of India. In our series percentage of ALL is higher (71.8%) compared to that observed by Khodaskar et al, from Nagpur; however the incidences of AML are comparable in both the series. The frequency of CML is also comparable with that reported by workers from Delhi, Nagpur and Thanjavur. The incidence is less in Kerala. However, in all these series from India, the frequency of CML is definitely higher than that reported by Meighan et al from U.S.A.
[Table - 1], [Table - 2], [Table - 3]