Ethnic differences in acute promyelocytic leukaemia between New Zealand Polynesian and European patients

Figures & data

Table 1. Clinical and laboratory features of patients with acute promyelocytic leukaemia diagnosed at Auckland City Hospital from February 2000 to January 2017.

	Total n = 55	Polynesians n = 16	Europeans n = 39	P-value
Age at presentation, mean (SD)	45.8 (19.9)	34.2 (16.0)	50.5 (19.5)	0.005^a
Male/Female (ratio)	27/28 (1:1)	7/9 (1:1.3)	20/19 (1:1)	0.612^b
Full blood count
Haemoglobin level g/L, mean (SD)	101.5 (25.0)	99.1 (21.1)	102.6 (26.7)	0.650^a
White cell count × 10^9/L, median (IQR)	2.1 (5.1)	4.3 (8.9)	1.9 (3.7)	0.080^c
Blast count × 10^9/L, median (IQR)	0.4 (4.8)	2.2 (6.7)	0.04 (2.4)	0.033^c
Neutrophil count × 10^9/L, median (IQR)	0.4 (0.9)	0.4 (0.9)	0.4 (0.9)	0.961^c
Platelet count × 10^9/L, median (IQR)	29.0 (49.0)	29.5 (25.0)	26.0 (59.0)	0.581^c
APL morphology, n (%)^e
Hypergranular	40 (81.6)	10 (71.4)	30 (85.7)	0.254^d
Microgranular	9 (18.4)	4 (28.6)	5 (14.3)
Coagulation profile, median (IQR)
Fibrinogen level g/L	1.9 (1.5)	1.6 (1.4)	2.0 (1.7)	0.225^c
APTT (sec)	31.0 (6.0)	33.0 (5.0)	30.0 (6.0)	0.287^c
PR	1.2 (0.3)	1.3 (0.3)	1.2 (0.2)	0.020^c
Karyotype, n (%)^f
+8	5 (38.5)	2 (50.0)	3 (33.3)	1.000^d
Other additional changes	8 (61.5)	2 (50.0)	6 (66.7)
BCR breakpoint, n (%)
BCR1	25 (59.5)	4 (40.0)	21 (65.6)	0.352^d
BCR2	1 (2.4)	0	1 (3.1)
BCR3	16 (38.1)	6 (60.0)	10 (31.3)
Prognostic category, n (%)
High risk	10 (18.9)	4 (25.0)	6 (16.2)	0.630^d
Intermediate risk	25 (47.2)	8 (50.0)	17 (45.9)
Low risk	18 (34.0)	4 (25.0)	14 (37.8)

NB. Where sums do not add up to the total of 55, this data is missing. N of categorical variables are shown. All continuous variables were calculated based on available data only (ranged from 15 to 16 Polynesian and 35–39 European patients).

Abbreviations: APL, acute promyelocytic leukaemia; APTT, activated partial thromboplastin time; BCR, breakpoint cluster region; Hb, haemoglobin; IQR, interquartile range; PR, prothrombin ratio; SD, standard deviation.

^aIndependent samples Student t-test (2-sided).

^bPearson Chi-square test.

^cMann-Whitney U test.

^dFisher’s exact test (2-sided).

^eOne patient had difficult morphology and was excluded from this analysis.

^fOther than t(15;17)(q24;q21).

Figure 1. Age distribution and survival of New Zealand Polynesian and European patients with acute promyelocytic leukaemia (APL). (A) Age at diagnosis of APL patients diagnosed at Auckland City Hospital (A–i) and recorded in the New Zealand Cancer Registry (A–ii) during 2000–2017. Bars indicate numbers of Polynesian patients (n = 16 in Auckland [i] and n = 46 in New Zealand [ii]) and European patients (n = 39 in Auckland [i] and n = 127 in New Zealand [ii]) categorized by their age at diagnosis. (B) Kaplan-Meier curves comparing cumulative survival probability between Polynesian and European patients with APL treated in Auckland City Hospital (B–i) and recorded in the New Zealand Cancer Registry (B–ii) from 2000–2017.

Table 2. Time to treatment (ATRA and chemotherapy), bleeding/thrombotic events, and transfusion requirements during induction.

		Total n = 53	Polynesians n = 15	Europeans = 38	P-value
Time to start ATRA (hours), median (IQR)		9.1 (24.0)	5.4 (7.0)	16.2 (33.0)	0.021^a
Time to start chemotherapy (hours), median (IQR)		51.7 (53.0)	62.1 (50.0)	50.0 (60)	0.907^a
Bleeding/thrombosis at presentation, n (%)	Any bleeding/thrombosis	24 (45.3%)	8 (53.3%)	16 (42.1%)	0.459^b
	Significant bleeding/thrombosis	7 (13.2%)	2 (13.3%)	5 (13.2%)	1.000^c
Bleeding/thrombosis within 30 days, n (%)	Any bleeding/thrombosis	24 (47.1%)	9 (64.3%)	15 (40.5%)	0.129^b
	Significant bleeding/thrombosis	13 (25.5%)	4 (28.6%)	9 (24.3%)	0.734^c
Number of days patients required transfusions (expressed per patient)	Platelets, median (IQR)	21.0 (19.0)	21.0 (14.0)	21.0 (22.0)	0.992^a
	FFP, mean (SD)	2.3 (6.5)	2.2 (7.4)	2.3 (6.2)	0.711^a
	Cryoprecipitate, mean (SD)	2.0 (3.3)	2.3 (3.0)	1.9 (3.5)	0.585^a
Number of units transfused per patient	Platelets, median (IQR)	8.0 (9.0)	8.0 (4.0)	8.0 (11.0)	0.919^a
	FFP, mean (SD)	2.0 (4.4)	1.1 (2.1)	2.4 (5.0)	0.712^a
	Cryoprecipitate, mean (SD)	2.9 (6.2)	2.2 (3.3)	3.1 (7.0)	0.619^a

NB. Total number of patients <55 due to missing data. N of categorical variables are shown. All continuous variables were calculated based on available data only (ranged from 13 to 15 Polynesian and 30–37 European patients).

Abbreviations: ATRA, all-trans retinoic acid; IQR, interquartile range; FFP, fresh frozen plasma; SD, standard deviation.

^aMann-Whitney U test.

^bPearson Chi-square test.

^cFisher’s exact test (2-sided).

Table 3. Long-term outcomes of patients with acute promyelocytic leukaemia treated at Auckland City Hospital.

	Total n = 54	Polynesians n = 16	Europeans n = 38	P-value
Deaths, n (%)
Within 30 days	3 (5.6%)	1 (6.3%)	2 (5.3%)	1.000^a
Beyond 30 days	13 (26.5%)	4 (28.6%)	9 (25.7%)	1.000^a
Overall	16 (30.8%)	5 (33.3%)	11 (29.7%)	1.000^a
Follow-up time (months), median (IQR)	80.4 (137.6)	68.2 (73.1)	89.8 (139.5)	0.193^b

NB. Total patient numbers <55 due to missing outcome data. All continuous data were calculated based on available data only (15 Polynesian and 37 European patients).

Abbreviations: IQR, interquartile range.

^aFisher’s exact test (2-sided).

^bMann-Whitney U test.

Table 4. Epidemiological data for patients with acute promyelocytic leukaemia recorded in the New Zealand Cancer Registry.

	Total n = 173	Polynesians n = 46	Europeans n = 127	P-value
Age at presentation, mean (SD)	47.0 (19.1)	35.6 (16.2)	51.1 (18.5)	<0.001^a
Male/Female (ratio)	93/80 (1:0.9)	25/21 (1:0.8)	68/59 (1:0.9)	0.925^b
Deaths, n (%)	60 (34.7%)	16 (34.8%)	44 (34.6%)	0.987^b

Abbreviations: SD, standard deviation.

^aIndependent samples Student t-test (2-sided).

^bPearson Chi-square test.

Figure 2. Overall survival of European, Māori and Pacific Island patients with acute promyelocytic leukaemia (APL). Kaplan-Meier curves comparing cumulative survival probability between European, Māori and Pacific Island patients with APL treated in Auckland City Hospital (A) and recorded in the New Zealand Cancer Registry (B) between 2000 and 2017.