Impact of parental socioeconomic factors on childhood cancer mortality: a population-based registry study

Figures & data

Table 1. Characteristics of the children diagnosed with cancer at the age of 0–19 years in 1990–2009.

	All diagnoses combined, n = 4437			ALL and LBL^a, n = 936 (21%)			CNS tumors^b , n = 927 (21%)			Other malignant neoplasms, n = 2574 (58%)
	n (%)	Deaths, n	Person-years	n (%)	Deaths, n	Person-years	n (%)	Deaths, n	Person-years	n (%)	Deaths, n	Person-years
Sex
Male	2358 (53)	441	10,152	506 (54)	88	2255	495 (53)	102	2072	1357 (53)	251	5825
Female	2079 (47)	328	9166	430 (46)	66	1939	432 (47)	102	1759	1217 (47)	160	5469
Age at diagnosis
Under 1 year	312 (7)	72	1193	30 (3)	9	108	54 (6)	26	143	228 (9)	37	942
1–9 years	1873 (42)	330	8169	652 (70)	82	3017	465 (50)	103	1933	756 (29)	145	3218
10–15 years	1083 (24)	184	4756	165 (18)	33	721	255 (28)	43	1108	663 (26)	108	2927
16–19 years	1169 (26)	183	5202	89 (10)	30	348	153 (17)	32	647	927 (36)	121	4207
Diagnostic period
1990–1994	1115 (25)	215	4786	256 (27)	48	1148	232 (25)	63	912	627 (24)	104	2726
1995–1999	1126 (25)	214	4871	218 (23)	44	949	233 (25)	55	960	675 (26)	115	2961
2000–2004	1125 (25)	167	4988	219 (23)	31	996	237 (26)	43	1009	669 (26)	93	2982
2005–2009	1071 (24)	173	4675	243 (26)	31	1101	225 (24)	43	949	603 (23)	99	2625
Combined parental income
Q1	439 (10)	92	1832	89 (10)	17	391	87 (10)	24	344	263 (11)	51	1097
Q2	700 (16)	123	3045	152 (17)	24	675	152 (17)	27	642	396 (16)	72	1729
Q3	769 (18)	123	3390	168 (18)	23	764	155 (17)	35	639	446 (18)	65	1987
Q4	1032 (24)	147	4623	210 (23)	31	953	225 (25)	39	979	597 (24)	77	2691
Information missing^c	159 (4)	29	674	23 (3)	3	105	32 (4)	8	125	104 (4)	18	444
Structural missing^d	1338 (31)	255	5754	294 (32)	56	1307	276 (31)	71	1101	768 (31)	128	3347
Parental educational level
Primary or less	477 (11)	89	2049	94 (10)	18	410	85 (9)	25	323	298 (12)	46	1316
Secondary	1858 (42)	346	8014	383 (41)	71	1691	383 (41)	85	1580	1092 (42)	190	4743
Post-secondary	2100 (47)	334	9246	459 (49)	65	2093	458 (49)	94	1923	1183 (46)	175	5230
Maternal employment status
Employed	3086 (70)	522	13,518	626 (67)	104	2802	626 (68)	135	2601	1834 (71)	283	8115
Unemployed	415 (9)	60	1845	85 (9)	10	394	85 (9)	15	360	245 (10)	35	1091
Student	143 (3)	34	586	26 (3)	6	109	41 (4)	12	158	76 (3)	16	319
Pensioner	80 (2)	12	359	9 (1)	≤3	42	15 (2)	≤3	65	56 (2)	8	252
Other non-working	649 (15)	125	2747	178 (19)	30	794	150 (16)	36	609	321 (12)	59	1344
Information missing	64 (1)	16	264	12 (1)	≤3	53	10 (1)	≤3	37	42 (2)	10	174
Paternal employment status
Employed	3591 (81)	605	15,719	783 (84)	124	3523	748 (81)	160	3113	2060 (80)	321	9082
Unemployed	357 (8)	69	1526	75 (8)	16	324	78 (8)	17	326	204 (8)	36	877
Student	72 (2)	16	298	18 (2)	≤6	82	19 (2)	≤6	71	35 (1)	8	146
Pensioner	139 (3)	22	614	16 (2)	≤6	73	29 (3)	≤6	118	94 (4)	13	423
Other non-working	79 (2)	17	327	16 (2)	≤6	70	14 (2)	≤6	52	49 (2)	9	205
Information missing	196 (4)	39	824	28 (3)	≤6	124	37 (4)	9	143	131 (5)	24	557
Mother’s age
Under 26 years	209 (5)	44	845	52 (6)	4	247	43 (5)	14	159	114 (4)	26	439
26–35 years	1393 (31)	251	6007	422 (45)	58	1930	309 (33)	80	1224	662 (26)	113	2853
36–45 years	2038 (46)	354	8914	375 (40)	72	1644	439 (47)	82	1881	1224 (48)	200	5389
Over 45 years	790 (18)	117	3530	87 (9)	20	374	136 (15)	28	567	567 (22)	69	2589
Information missing	7 (0)	0	23	0 (0)	0	0	0 (0)	0	0	7 (0)	0	23
Number of siblings
No siblings	587 (13)	115	2465	126 (13)	21	566	123 (13)	36	461	338 (13)	58	1438
1 sibling	1680 (38)	292	7351	374 (40)	62	1661	357 (39)	75	1510	949 (37)	155	4180
2 siblings	1253 (28)	201	5528	277 (30)	45	1256	242 (26)	47	1021	734 (29)	109	3251
3 siblings	515 (12)	95	2218	82 (9)	13	368	111 (12)	24	450	322 (13)	58	1400
4 or more siblings	402 (9)	66	1757	77 (8)	13	344	94 (10)	22	389	231 (9)	31	1025
Mother’s family type
Living with a spouse	3712 (84)	635	16,212	789 (84)	129	3547	768 (83)	170	3180	2155 (84)	336	9485
Living alone	590 (13)	107	2533	127 (14)	21	559	140 (15)	28	581	323 (13)	58	1392
Information missing	134 (3)	27	570	20 (2)	4	88	19 (2)	6	69	95 (4)	17	413
Father’s family type
Living with a spouse	3744 (84)	631	16,370	802 (86)	124	3623	778 (84)	171	3226	2164 (84)	336	9521
Living alone	108 (2)	18	479	21 (2)	8	81	15 (2)	≤33	65	72 (3)	7	334
Information missing	585 (13)	120	2470	113 (12)	22	491	134 (14)	≤33	539	338 (13)	68	1440

^a Acute lymphatic leukemia and lymphoblastic lymphoma.

^b Central nervous system tumors.

^c Missing information from 1996 and onwards.

^d Information missing due to data limitations with diagnostic year being 1995 or before.

Table 2. Five-year cancer mortality for all patients in two adjusted models.

	Model 1^a		Model 2^b
	Deaths, n	HR(CI 95%)	Deaths, n	HR(CI 95%)
Sex
Male	441	1	440	1
Female	328	0.82 (0.71–0.95)	325	0.82 (0.71–0.94)
Cancer type
ALL and LBL^c	154	1	154	1
CNS tumors^d	204	1.46 (1.18–1.81)	203	1.45 (1.17–1.79)
Other malignant neoplasms	411	0.98 (0.80–1.20)	408	0.96 (0.79–1.18)
Combined parental income
Q1	92	1	92	1
Q2	123	0.83 (0.63–1.09)	123	0.83 (0.63–1.10)
Q3	123	0.76 (0.58–1.00)	123	0.77 (0.58–1.04)
Q4	147	0.68 (0.52–0.89)	147	0.71 (0.52–0.96)
Information missing^e	29	0.93 (0.61–1.41)	27	0.70 (0.38–1.27)
Structural missing^f	255	0.78 (0.53–1.15)	253	0.76 (0.51–1.13)
Highest parental education
Primary education or less	89	1	86	1
Secondary education	346	1.00 (0.79–1.27)	345	1.06 (0.83–1.37)
Post-secondary education	334	0.84 (0.66–1.06)	334	0.91 (0.70–1.19)
Maternal employment status
Employed	522	1	522	1
Unemployed	60	0.84 (0.64–1.09)	60	0.75 (0.57–0.99)
Student	34	1.39 (0.98–1.98)	34	1.24 (0.86–1.78)
Pensioner	12	0.91 (0.51–1.62)	12	0.84 (0.46–1.50)
Other non-working	125	1.10 (0.90–1.35)	124	1.00 (0.81–1.24)
Information missing	16	1.61 (0.98–2.66)	13	1.39 (0.76–2.55)
Paternal employment status
Employed	605	1	605	1
Unemployed	69	1.14 (0.89–1.47)	69	1.05 (0.81–1.36)
Student	16	1.31 (0.80–2.15)	16	1.12 (0.67–1.86)
Pensioner	22	1.00 (0.65–1.54)	22	0.93 (0.60–1.45)
Other non-working	17	1.41 (0.87–2.29)	17	1.28 (0.78–2.10)
Information missing	39	1.26 (0.91–1.75)	36	1.26 (0.78–2.02)
Mother’s age
Under 26 years	44	1.11 (0.78–1.56)	43	0.94 (0.65–1.35)
26–35 years	251	0.95 (0.78–1.15)	251	0.92 (0.76–1.12)
36–45 years	354	1	354	1
Over 45 years	117	0.89 (0.71–1.11)	117	0.90 (0.72–1.12)
Information missing	3	3.54 (1.13–11.05)	3	2.59 (0.72–9.37)

^a Adjusted for age at diagnosis (categorized as follows: < 1, 1–9, 10–15 and 16–19 years, respectively) and diagnostic period (categorized as follows: 1990–1994, 1995–1999, 2000–2004 and 2005–2009).

^b Adjusted for age at diagnosis and diagnostic period and all others.

^c Acute lymphatic leukemia and lymphoblastic lymphoma.

^d Central nervous system tumors.

^e Missing information from 1996 and onwards.

^f Information missing due to data limitations with diagnostic year being 1995 or before.

Table 3. Five-year cancer mortality for different cancer types adjusted for age at diagnosis^a and diagnostic period^b.

	ALL and LBL^c		CNS tumors^d		Other malignant neoplasms
	Deaths, n	HR (CI 95%)	Deaths, n	HR (CI 95%)	Deaths, n	HR (CI 95%)
Sex
Male	88	1	102	1	251	1
Female	66	0.86 (0.63–1.19)	102	1.16 (0.88–1.52)	160	0.69 (0.56–0.84)
Combined parental income
Q1	17	1	24	1	51	1
Q2	24	0.91 (0.49–1.71)	27	0.62 (0.35–1.07)	72	0.89 (0.62–1.28)
Q3	23	0.76 (0.40–1.44)	35	0.92 (0.54–1.55)	65	0.71 (0.49–1.03)
Q4	31	0.86 (0.47–1.57)	39	0.69 (0.40–1.18)	77	0.62 (0.43–0.90)
Information missing^e	3	0.60 (0.18–2.08)	8	1.16 (0.51–2.63)	18	0.93 (0.54–1.61)
Structural missing^f	56	1.08 (0.45–2.60)	71	0.56 (0.25–1.28)	128	0.83 (0.50–1.37)
Highest parental education
Primary or less	18	1	25	1	46	1
Secondary	71	1.12 (0.66–1.88)	85	0.75 (0.48–1.17)	190	1.09 (0.79–1.51)
Post-secondary	65	0.82 (0.48–1.40)	94	0.69 (0.44–1.08)	175	0.89 (0.64–1.25)
Maternal employment status
Employed	104	1	135	1	283	1
Unemployed	10	0.66 (0.35–1.28)	15	0.77 (0.45–1.32)	35	0.91 (0.64–1.30)
Student	6	2.02 (0.88–4.64)	12	1.47 (0.81–2.67)	16	1.29 (0.78–2.15)
Pensioner	≤5	0.50 (0.07–3.58)	≤7	0.97 (0.31–3.06)	8	1.03 (0.51–2.08)
Other non-working	30	1.24 (0.82–1.89)	36	0.98 (0.67–1.43)	59	1.11 (0.83–1.48)
Information missing	≤5	1.72 (0.54–5.50)	≤7	1.70 (0.54–5.38)	10	1.73 (0.92–3.25)
Paternal employment status
Employed	124	1	160	1	321	1
Unemployed	16	1.43 (0.85–2.42)	17	1.01 (0.61–1.67)	36	1.17 (0.83–1.65)
Student	≤5	0.85 (0.21–3.46)	6	1.34 (0.59–3.04)	8	1.43 (0.71–2.89)
Pensioner	≤5	0.81 (0.26–2.59)	6	1.10 (0.48–2.52)	13	1.01 (0.58–1.77)
Other non-working	≤5	1.20 (0.38–3.80)	5	2.11 (0.86–5.16)	9	1.40 (0.72–2.72)
Information missing	6	1.13 (0.50–2.58)	9	1.38 (0.70–2.72)	24	1.30 (0.86–1.97)
Mother’s age
Under 26 years	4	0.50 (0.18–1.42)	14	1.38 (0.75–2.55)	26	1.40 (0.87–2.23)
26–35 years	58	0.84 (0.57–1.24)	80	1.22 (0.86–1.74)	113	0.91 (0.69–1.21)
36–45 years	72	1	82	1	200	1
Over 45 years	20	0.94 (0.55–1.60)	28	1.18 (0.74–1.88)	69	0.80 (0.60–1.07)
Information missing	0	–	0	–	3	3.66 (1.17–11.47)

^a Categorized as follows: <1, 1–9, 10–15 and 16–19 years, respectively.

^b Categorized as follows: 1990–1994, 1995–1999, 2000–2004and 2005–2009.

^c Acute lymphatic leukemia and lymphoblastic lymphoma.

^d Central nervous system tumors.

^e Missing information from 1996 and onwards.

^f Information missing due to data limitations with diagnostic year being 1995 or before.

Table 4. Effect of diagnostic period, education and maternal co--habitation on five-year cancer mortality and five-year survival.

	n	Deaths, n	Five-year mortality, HR (95% CI)^a	Five-year survival % (95% CI)
Period and education
Diagnostic period – 1990–1999
Parental education primary or secondary	1271	257	1	80 (78–83)
Parental education post-secondary	970	186	0.94 (0.77–1.13)	81 (79–83)
Diagnostic period 2000–2009
Parental education primary or secondary	1064	199	0.90 (0.75–1.09)	82 (80–84)
Parental education post-secondary	1132	164	0.66 (0.54–0.81)	86 (84–88)
Period, education and maternal co--habitation
Diagnostic period 1990–1999
Parental education primary or secondary and mother co--habiting	1061	209	1	80 (78–82)
Parental education primary or secondary and mother living alone	167	27	0.83 (0.56–1.24)	84 (77–89)
Parental education post-secondary and mother co--habiting	868	163	0.93 (0.76–1.14)	81 (78–84)
Parental education post-secondary and mother living alone	85	17	1.01 (0.62–1.66)	80 (70–87)
Diagnostic period 2000–2009
Parental education primary or secondary and mother co--habiting	801	130	0.81 (0.65–1.01)	84 (81–86)
Parental education primary or secondary and mother living alone	211	46	1.18 (0.85–1.62)	78 (72–83)
Parental education post-secondary and mother co--habiting	982	133	0.66 (0.53–0.82)	86 (84–88)
Parental education post-secondary and mother living alone	127	17	0.67 (0.41–1.11)	87 (79–91)

^aAdjusted for age at diagnosis categorized as follows: <1, 1–9, 10–15 and 16–19 years, respectively.

Figure 1. The Regression-tree model and five-year cancer survival. A) Period effect and the effect of parental education. B) Period effect and the effect of parental education and maternal co-habitation.