Changes in body mass index and alcohol and tobacco consumption among breast cancer survivors and cancer-free women: A prospective study in the Danish Diet, Cancer and Health Cohort

Figures & data

Table I. Demographic characteristics at baseline and health behaviour at baseline and follow-up among 23 420 Danish women in the Diet, Cancer and Health cohort study.

Health behaviour	Women with breast cancer N = 449			Cancer-free women N = 22 971
	Baseline N (%)	Follow-up N (%)	p^a	Baseline N (%)	Follow-up N (%)	p^a
Age at baseline (years)
Range	50.3–65.4			50.1–65.8
Mean (SD)	56.7 (4.1)			56.7 (4.4)
Education
Basic/high school	69 (16)			4043 (18)
Vocational training	131 (29)			7242 (32)
Higher education	246 (55)			11623 (51)
Unknown	3 (1)			63 (0)
Marital status
Never married	28 (6)			1420 (6)
Divorced or widowed	126 (29)			6007 (26)
Married or registered partner	292 (64)			15466 (68)
Unknown	3 (1)			78 (1)
Tobacco (g/day)
Mean	4.5	3.4		4.1^b	3.5^c
0	306 (68)	334 (74)	< 0.0001	16 144 (70)	17 210 (75)	< 0.0001
1–10	53 (12)	49 (11)		2672 (12)	2357 (10)
11–20	80 (18)	60 (13)		3527 (15)	2895 (13)
≥ 20	10 (2)	6 (1)		609 (3)	507 (2)
Alcohol (drinks/day)^h
Mean	15.0^d	15.6		13.2^e	14.0
0	25 (6)	19 (4)	< 0.0001	1442 (6)	1149 (5)	< 0.0001
1–2	325 (73)	318 (71)		17 487 (76)	17 178 (75)
> 2	98 (22)	111 (25)		4029 (18)	4644 (20)
BMI
Mean	25.3	25.3^f		25.5	25.4^g
< 18.5	8 (2)	7 (2)	< 0.0001	245 (1)	343 (1)	< 0.0001
18.5–24.9	236 (53)	237 (53)		11 815 (51)	11 899 (52)
25–29.9	151 (34)	145 (32)		7828 (34)	7621 (33)
≥ 30	54 (12)	58 (13)		3067 (13)	3038 (13)

All percentages do not add up to 100.

^aWithin group differences between baseline and follow-up are based on women for whom no values were missing at either time; ^bInformation missing for 19; ^cInformation missing for 2; ^dInformation missing for 1; ^eInformation missing for 13; ^fInformation missing for 16; ^gInformation missing for 72; ^hOne drink of alcohol corresponds to 12 g.

Table II. Clinical and prognostic characteristics of 379 women with breast cancer in the Diet, Cancer and Health cohort study.

Characteristic	N (%)
Tumour size (cm)
≤ 2	260 (69)
> 2–≤ 5	112 (29)
> 5	7 (2)
No. of positive lymph nodes
0	228 (60)
1–3	100 (26)
4–9	34 (9)
≥ 10	17 (4)
Histological type and malignancy grade
Ductal grade I	127 (35)
Ductal grade II	113 (31)
Ductal grade III	46 (13)
Non-ductal	81 (22)
Receptor status
Negative	59 (16)
Positive	313 (83)
Unknown	7 (2)
Chemotherapy
No	342 (90)
Yes	37 (10)
Hormone therapy
No	220 (58)
Yes	159 (42)
Radiation
No	137 (36)
Yes	242 (64)

We excluded 70 women with breast cancer who were not enrolled in a treatment protocol, or for whom information on tumour size was unavailable. All percentages do not add up to 100. The treatments (chemotherapy, hormone therapy and radiation) are not mutually exclusive.

Table III. Regression-derived coefficients (β) and 95% confidence intervals for changes in health behaviour by breast cancer diagnosis, education and marital status among all women and women decreased their BMI, smoking or drinking in the Diet, Cancer and Health cohort study.

Characteristic	All women β [95% CI]			Women who decreased behaviour β [95% CI]^1
	Tobacco N = 23 252	Alcohol N = 23 259	BMI N = 23 200	Tobacco N = 3420	Alcohol N = 10 630	BMI N = 12 421
Breast cancer
No	–	–	–	–	–	–
Yes	–0.3 [–0.8; 0.1]	0.1 [−1.0; 1.3]	0.1 [−0.1; 0.3]	0.5 [−0.7; 1.8]	−0.7 [−1.6; 0.1]	0.2 [0.1; 0.4]
Education
Basic/high school	–	–	–	–	–	–
Vocational training	−0.5 [−0.6; −0.3]	1.0 [0.5; 1.5]	−0.1 [−0.2; −0.0]	0.4 [−0.1; 0.9]	−0.7 [−1.0; −0.3]	0.0 [−0.1; 0.0]
Higher education	−0.6 [−0.7; −0.4]	1.6 [1.2; 2.1]	−0.2 [−0.3; −0.1]	0.5 [0.0; 1.0]	−1.0 [−1.4; −0.7]	−0.0 [−0.1; 0.0]
Marital status
Never married	–	–	–	–	–	–
Divorced or widowed	−0.1 [−0.3; 0.2]	0.0 [–0.7; 0.7]	0.2 [0.1; 0.3]	0.6 [−0.2; 1.4]	0.0 [−0.5; 0.6]	−0.1 [−0.1; 0.0]
With partner	−0.3 [−0.5; −0.0]	0.6 [−0.1; 1.2]	−0.0 [−0.1; 0.1]	1.0 [0.2; 1.8]	−0.7 [−1.2; −0.1]	−0.1 [−0.2; 0.0]

Regression coefficients (β) reflect differences in health behaviour change for each given increment in the independent variable. Analyses are mutually adjusted and adjusted for age at baseline.

¹A positive estimate indicates a larger decrease; a negative estimate indicates a smaller decrease.

Table IV. Regression-derived coefficients (β) and 95% confidence intervals for change in health behaviour between baseline and follow-up by demographic and clinical factors in women with breast cancer.

	All women β [95% CI]			Women who decrease behaviour β [95% CI]^1
	Tobacco N = 359	Alcohol N = 358	BMI N = 357	Tobacco N = 69	Alcohol N = 181	BMI N = 169
Education
Basic/high school	–	–	–	–	–	–
Vocational training	−0.3 [−1.7; 1.1]	−0.5 [−4.1; 3.0]	0.0 [−0.7; 0.7]	0.7 [−2.9; 4.3]	0.1 [−2.6; 2.9]	−0.6 [−1.4; 0.2]
Higher education	0.3 [−1.0; 1.6]	−0.1 [−3.4; 3.2]	−0.0 [−0.7; 0.6]	−0.7 [−4.3; 2.9]	0.1 [−2.4; 2.6]	−0.4 [−1.1; 0.4]
Marital status
Never married	–	–	–	–	–	–
Divorced or widowed	−0.9 [−2.8; 1.0]	−3.8 [−8.9; 1.1]	0.4 [−0.5; 1.4]	5.6 [−1.2; 12.3]	0.7 [−3.1; 4.5]	0.2 [−0.9; 1.4]
With partner	−0.7 [−2.6; 1.1]	−1.4 [−6.1; 3.3]	0.4 [−0.6; 1.4]	2.8 [−3.8; 9.4]	−0.5 [−4.1; 3.1]	−0.1 [−1.1; 1.0]
Chemotherapy
No	–	–	–	–	–	–
Yes	−0.8 [−2.9; 1.4]	1.6 [−4.0; 7.2]	0.3 [−0.8; 1.4]	5.8 [−3.4; 15.0]	−2.8 [−7.5; 1.9]	−0.7 [−2.1; 0.6]
Hormone therapy
No	–	–	–	–	–	–
Yes	0.6 [−0.6; 1.8]	−0.3 [−3.3; 2.8]	0.0 [−0.6; 0.6]	3.5 [−1.0; 8.0]	0.1 [−2.2; 2.4]	−0.1 [−0.9; 0.6]
Radiation
No	–	–	–	–	–	–
Yes	0.3 [−0.7; 1.4]	1.5 [−1.2; 4.2]	0.4 [−0.1; 0.9]	−0.9 [−4.1; 2.4]	−1.9 [−3.9; 0.1]	−0.2 [−0.9; 0.4]

Regression coefficients (β) reflect differences in health behaviour change for each given increment in the independent variable. Analyses are adjusted for age, time between baseline date and date of diagnosis, tumour size, number of positive lymph nodes, histological type, grade of malignancy and receptor status and are mutually adjusted.

¹A positive estimate indicates a larger decrease; a negative estimate indicates a smaller decrease.