Can reproductive pattern explain better survival of women with lung cancer?

Figures & data

Table I.  Relative risk for dying from lung cancer (hazard ratio, HR) by sex, age, extent of disease and histological type.

Variable	No. of patients	Crude HR	95% CI	Adjusted HR^a	95% CI
Sex
Male	4797	Reference	–	Reference	–
Female	4235	0.91	0.87–0.95	0.91	0.87–0.95
Age
≤ 39	479	Reference	–	Reference	–
40–49	2731	1.11	1.00–1.23	1.10	0.99–1.22
50–59	4688	1.19	1.08–1.32	1.23	1.11–1.36
60–65	1134	1.15	1.03–1.29	1.20	1.07–1.34
Extent of disease^b
Localized	1708	Reference	–	Reference	–
Regional	2942	2.61	2.43–2.80	2.63	2.45–2.82
Metastatic	3570	4.97	4.64–5.33	5.04	4.70–5.41
Histological type^c
Squamous cell carcinoma	1807	Reference	–	Reference	–
Small cell carcinoma	1744	1.17	1.10–1.26	0.93	0.87–1.00
Adenocarcinoma	3546	1.12	1.06–1.19	1.05	0.99–1.12
Large cell carcinoma	671	1.38	1.26–1.52	1.21	1.10–1.32

CI, confidence interval.

^aAdjusted for all other variables listed in table.

^bInformation on extent of disease missing for 812 patients (9%).

^cHistological type other or unspecified for 1264 patients (14%).

Table II.  Selected reproductive characteristics of Danish lung cancer patients, 1978–99.

	Men		Women
Variable	Number of patients	%	Number of patients	%
Number of children
0	898	18.7	485	11.5
1–3	3418	71.3	3322	78.4
4–11	481	10.0	428	10.1
Age at birth of first child (years)
≤ 19	238	6.1	1012	27.0
20–24	1707	43.8	1879	50.1
25–29	1339	34.4	647	17.3
≥ 30	610	15.7	212	5.6
Sex ratio
Equal	1034	26.5	966	25.8
More boys	1526	39.2	1527	40.7
More girls	1339	34.3	1257	33.5

Table III.  Hazard ratios for selected reproductive factors in Danish male and female lung cancer patients, 1978–99, by sex.

	Men		Women
Variable	Adjusted HR	95% CI	Adjusted HR	95% CI
Number of children
0	1.24	1.15–1.34	1.14	1.03–1.26
1–3	Reference	–	Reference	–
4–11	1.09	0.95–1.27	1.08	0.97–1.20
Age at birth of first child (years)
≤ 19	0.96	0.83–1.11	0.97	0.90–1.06
20–24	Reference	–	Reference	–
25–29	0.94	0.87–1.02	0.99	0.91–1.09
≥ 30	1.03	0.94–1.14	0.90	0.77–1.04
Sex ratio
Equal	Ref.	–	Ref.	–
More boys	0.93	0.86–1.02	1.04	0.96–1.13
More girls	1.00	0.91–1.09	1.09	1.00–1.19

95% CI, 95% confidence interval.

Hazard ratios adjusted for age, extent of disease and histological type.

Figure 1.  Survival of Danish lung cancer patients with localized or regional disease by number of children and histological type, with 95% confidence intervals.