Risk of second primary malignancies in a population-based study of adult patients with essential thrombocythemia

Table 1 Characterstics of patients with essential thrombocythemia

Characteristics	n (%)
Age
< 50 yr	1600 (19.7)
50-70 yr	2958 (36.5)
> 70 yr	3558 (43.8)
Sex
Male	3195 (39.4)
Female	4921 (60.6)
Race
White	6332 (78)
African American	971 (12)
Other1	576 (7.1)
Unknown	237 (2.9)
Marital status
Single/unmarried	1152 (14.2)
Married	3815 (47)
Divorced/separated/widowed	2125 (26.2)
Unknown	1024 (12.6)
Year at diagnosis
2001-2005	3035 (37.3)
2006-2010	4251 (52.4)
2011-present	840 (10.3)

¹Other race indicates Asian, Hispanic, Native North American and other racial groups.

Table 2 Age standardized cause-specific survival rates of the study population

Survival at defined time period	Entire cohort	Male	Female	Patients < 50 yr	Patients ≥ 50 yr
12 mo	99.10%	98.80%	99.30%	99.90%	98.90%
24 mo	98.30%	97.80%	98.70%	99.80%	97.90%
36 mo	97.20%	96.20%	97.90%	99.70%	96.50%
48 mo	96.10%	94.80%	96.90%	99.70%	95.00%
60 mo	94.90%	93.10%	96.00%	99.40%	93.50%

The percentage indicates cause-specific survival of specified population at defined time period.

Table 3 Risk of second primary malignancies among the study population

SPM	Observed	SIR	95%CI	AER	P-value
All sites	201	1.26	1.09-1.45	37.44	0.002
Solid	162	1.15	0.98-1.35	19.43	0.074
Colorectal	12	0.66	0.34-1.15	-5.62	0.916
Lung/bronchus	31	1.31	0.89-1.86	6.67	0.133
Breast	24	1.06	0.68-1.58	1.29	0.743
Prostate	24	1.11	0.71-1.65	2.14	0.594
Kidney	10	2.40	1.15-4.42	5.27	0.014
Lymphoma	12	1.59	0.82-2.78	4.02	0.127
Leukemia	17	3.78	2.20-6.05	11.28	< 0.001
AML	10	7.74	3.71-14.24	7.86	< 0.001

AER: Absolute excess risk; SIR: Standardized incidence ratio; SPM: Second primary malignancies.

Table 4 Risk of second primary malignancies based on the follow-up duration

SPM	Overall SIR (95%CI)	SIR at 6-23 mo follow-up (95%CI)	SIR at > 24 mo follow-up (95%CI)
All sites	1.26 (1.09-1.45)1	1.16 (0.9-1.49)	1.31 (1.1-1.55)1
Solid malignancies	1.15 (0.98-1.35)	1.09 (0.82-1.43)	1.18 (0.97-1.43)
Colorectal	0.66 (0.34-1.15)	0.47 (0.10-1.38)	0.76 (0.35-1.44)
Lung/bronchus	1.31 (0.89-1.86)	1.48 (0.76-2.58)	1.23 (0.74-1.92)
Breast	1.06 (0.68-1.58)	0.91 (0.37-1.88)	1.14 (0.66-1.82)
Prostate	1.11 (0.71-1.65)	1.03 (0.45-2.03)	1.15 (0.66-1.87)
Kidney	2.40 (1.15-4.42)1	0.71 (0.02-3.95)	3.27 (1.5-6.21)1
Hematologic malignancies	2.36 (1.63-3.29)1	2.03 (0.97-3.73)	2.53 (1.62-3.76)1
Lymphoma	1.59 (0.82-2.78)	1.56 (0.42-3.99)	1.61 (0.69-3.17)
Leukemia	3.78 (2.2-6.05)1	3.88 (1.42-8.44)1	3.72 (1.86-6.66)1
AML	7.74 (3.71-14.24)1	9.02 (2.46-23.09)1	7.08 (2.6-15.4)1

¹Indicates a statistically significant value. AML: Acute myeloid leukemia; SIR: Standardized incidence ratio; SPM: Second primary malignancies.

Table 5 Risk of secondary primary malignancies based on age at the time of diagnosis of essential thrombocythemia

SPM	Overall SIR (95%CI)	SIR for age group, 18-60 yr (95%CI)	SIR for age group, > 60 yr (95%CI)
All sites	1.26 (1.09-1.45)1	1.78 (1.31-2.36)1	1.15 (0.98-1.35)
Solid tumors	1.15 (0.98-1.35)	1.75 (1.27-2.35)1	1.03 (0.85-1.23)
Colorectal	0.66 (0.34-1.15)	1.33 (0.27-3.88)	0.56 (0.26-1.07)
Lungs/bronchus	1.31 (0.89-1.86)	2.36 (0.86-5.13)	1.19 (0.77-1.75)
Breast	1.06 (0.68-1.58)	1.08 (0.40-2.35)	1.06 (0.63-1.67)
Prostate	1.11 (0.71-1.65)	1.91 (0.82-3.76)	0.92 (0.52-1.49)
Kidney	2.40 (1.15-4.42)1	2.32 (0.28-8.37)	2.42 (1.05-4.78)1
Lymphoma	1.59 (0.82-2.78)	1.72 (0.21-6.23)	1.57 (0.75-2.88)
Leukemia	3.78 (2.2-6.05)1	3.74 (0.45-13.51)	3.78 (2.12-6.24)1
AML	7.74 (3.71-14.24)1	12.73 (1.54-45.98)1	7.06 (3.05-13.90)1

¹Indicates a statistically significant value. AML: Acute myeloid leukemia; SIR: Standardized incidence ratio; SPM: Second primary malignancies.