Life-Course Trajectories of Physical Activity and Melanoma Risk in a Large Cohort of Norwegian Women

Figures & data

Figure 1 Flowchart of the subcohorts from the Norwegian Women and Cancer (NOWAC) study for the analysis of life-course trajectories of physical activity (PA) and risk of melanoma, 1991–2018.

Table 1 Baseline Characteristics of the Study Sample from the Norwegian Women and Cancer Study (1991–2018, n = 152,248), Stratified by Subcohorts Labelled According to Age at Baseline

	Subcohorts
	31–39 years^a	40–49 years^a	≥50 years^a,b
Number of participants, n (%)	27,098 (17.8)	52,515 (34.5)	72,635 (47.7)
Melanoma cases, n (%)	248 (15.8)	610 (38.9)	711 (45.3)
Year of recruitment, %
1991–1992	86.5	53.9	2.1
1997–1998	13.5	20.5	32.9
2003–2007	0.0	25.5	64.9
Birth cohort, %
1927–1944	0.0	10.6	35.2
1945–1952	19.8	56.2	49.0
1953–1965	80.2	33.2	15.7
Follow-up time (years), mean (SD)	24.6 (5.6)	20.3 (6.9)	14.4 (5.0)
Age at recruitment, mean (SD)	36.7 (2.1)	45.8 (2.8)	56.6 (4.7)
Age at end of follow-up, mean (SD)	61.3 (6.1)	66.1 (6.2)	71.0 (6.8)
Age at diagnosis, mean (SD)	52.8 (8.2)	59.8 (7.4)	66.8 (7.6)
Education, %
≤10	27.2	31.9	35.2
11–13	32.7	30.0	26.0
≥14	38.9	34.6	31.9
Missing	1.2	3.5	6.9
Smoking, %
Never	31.8	33.3	37.0
Former	27.0	33.2	37.6
Current	39.7	32.5	24.8
Missing	1.5	1.0	0.6
BMI (kg/m^2), mean (SD)	22.6 (3.3)	23.9 (3.7)	25.2 (4.1)
BMI category, %
Normal and underweight (<25.0 kg/m^2)	80.7	68.8	54.5
Overweight (25.0–29.9 kg/m^2)	14.2	22.9	32.0
Obese (≥30 kg/m^2)	3.5	6.5	11.1
Missing	1.6	1.8	2.4
Hair color, %
Black/dark brown	14.3	15.1	16.8
Brown	33.7	38.1	37.8
Blond/yellow	34.1	36.1	37.5
Red	2.4	2.8	3.1
Missing	15.6	7.9	4.7
Ambient UVR of residence, %
Low (northern Norway)	11.2	18.5	26.6
Medium-low (central Norway)	14.3	12.9	8.9
Medium (southwestern Norway)	20.0	17.3	18.9
Highest (southeastern Norway)	54.6	51.3	45.5
Sunburns (per year)^c, %
Never	24.8	19.9	14.6
1	27.3	23.6	28.6
≥2	38.3	36.6	49.7
Missing	5.5	17.4	9.2
Sunbathing vacations (weeks/year)^c, %
Never	24.8	19.9	14.6
1	27.3	23.6	28.6
2–3	32.5	30.0	38.2
≥4	5.8	6.6	11.5
Missing	9.6	20.0	7.1
Indoor tanning^c, %
Never	35.2	36.9	41.6
Rarely	44.1	33.8	40.7
≥1 per month	13.7	13.2	12.1
Missing	6.9	16.1	5.6
PA at age 14, mean (SD)^d	6.5 (2.0)	6.5 (2.0)	6.8 (2.0)
PA at age 30, mean (SD)^e	5.8 (1.8)	6.2 (1.8)	6.7 (1.8)
PA at baseline, mean (SD)^f	5.7 (1.9)	5.7 (1.9)	5.7 (1.9)

Notes: ^aAge when recording information on current physical activity; ^bRange 50–76 years at baseline; ^cDuring the last decade. ^dMissing: 31–39 (n = 257), 40–49 (n = 2760), ≥50 (n = 7473). ^eMissing: 31–39 (n = 1108), 40–49 (n = 1631), ≥50 (n = 4665). ^fMissing: 31–39 (n = 133), 40–49 (n = 174), ≥50 (n = 347).

Abbreviations: BMI, body mass index; PA, physical activity; SD, standard deviation; UVR, ultraviolet radiation.

Figure 2 Class-specific average predicted life-course trajectories (bold lines) of physical activity for each subcohort: 31–39 years (A), 40–49 years (B) and ≥50 years (C) at baseline, the Norwegian Women and Cancer study, 1991–2018, n = 152,248.

Note: The thinner lines in the background represent observed individual trajectories of 500 participants randomly selected in each subcohort.

Figure 3 Sankey diagrams of physical activity trajectory classes obtained with latent class mixed model (LCMM) and naïve life-course trajectory analysis, for each subcohort: 31–39 years (A), 40–49 years (B) and ≥50 years (C) at baseline, in the Norwegian Women and Cancer study, 1991–2018, n = 137,800.

Table 2 Hazard Ratios (HRs) and 95% Confidence Intervals (CIs) for Melanoma Risk in Life-Course Physical Activity Trajectories (Latent Class Mixed Model) Using the Moderate Trajectory Class as Reference in Each Subcohort of the Norwegian Women and Cancer Study, 1991–2018, n = 130,259

Classes	n (Cases)^b	Model 0^c	Model 1^d	Model 2^e
31–39 years^a	21,129 (220)
Low	1769 (16)	0.89 (0.59–1.34)	0.90 (0.60–1.35)	0.91 (0.60–1.36)
Moderate	7181 (77)	1.00	1.00	1.00
High	3535 (35)	0.93 (0.67–1.30)	0.94 (0.67–1.31)	0.92 (0.66–1.29)
Decreasing	7420 (73)	0.93 (0.74–1.15)	0.93 (0.75–1.16)	0.93 (0.75–1.16)
Increasing	2224 (18)	0.75 (0.53–1.06)	0.76 (0.54–1.07)	0.77 (0.54–1.08)
40–49 years^a	45,839 (540)
Low	4245 (44)	0.85 (0.68–1.08)	0.87 (0.69–1.10)	0.87 (0.69–1.10)
Moderate	19,387 (227)	1.00	1.00	1.00
High	9388 (119)	1.11 (0.93–1.32)	1.13 (0.95–1.35)	1.15 (0.97–1.37)
Decreasing	12,819 (151)	1.02 (0.89–1.18)	1.03 (0.90–1.19)	1.03 (0.90–1.19)
≥50 years^a	63,291 (617)
Low	3678 (31)	0.84 (0.65–1.07)	0.85 (0.66–1.09)	0.84 (0.65–1.08)
Moderate	29,132 (304)	1.00	1.00	1.00
High	15,419 (146)	0.88 (0.75–1.02)	0.89 (0.77–1.04)	0.90 (0.78–1.05)
Decreasing	15,063 (136)	0.88 (0.77–1.00)	0.91 (0.80–1.03)	0.92 (0.81–1.04)

Notes: ^aSubcohorts are labelled by age at baseline. ^bWeighted class-specific sample size (n) is the sum of participants’ weights in the class and weighted class-specific number of cases (cases) is the sum of cases’ weights in the class (see Statistical analyses). ^cModel 0: Cox proportional hazards model stratified by year of recruitment, and with age as time scale. ^dModel 1: model 0 + education and smoking status. ^eModel 2: model 1 + hair color, ambient ultraviolet radiation of residence and height.

Table 3 Hazard Ratios (HRs) and 95% Confidence Intervals (CIs) for Melanoma Risk in Life-Course Naïve Trajectories of Physical Activity Using the Moderate Trajectory Class as Reference for Each Subcohort in the Norwegian Women and Cancer Study, 1991–2018, n = 119,768

Classes	n (Cases)^b	Model 0^c	Model 1^d	Model 2^e
31–39 years^a	21,596 (215)
Low	2387 (20)	0.74 (0.46–1.20)	0.75 (0.46–1.20)	0.75 (0.46–1.21)
Moderate	9277 (104)	1.00	1.00	1.00
High	6350 (58)	0.82 (0.60–1.13)	0.82 (0.60–1.13)	0.82 (0.59–1.12)
Decreasing	2489 (22)	0.80 (0.51–1.27)	0.83 (0.52–1.31)	0.83 (0.52–1.32)
Increasing	1093 (11)	0.90 (0.48–1.67)	0.91 (0.49–1.70)	0.92 (0.49–1.71)
40–49 years^a	42,388 (510)
Low	3978 (47)	1.00 (0.73–1.38)	1.02 (0.74–1.41)	1.02 (0.74–1.40)
Moderate	17,202 (191)	1.00	1.00	1.00
High	14,232 (183)	1.18 (0.97–1.45)	1.20 (0.98–1.47)	1.21 (0.99–1.48)
Decreasing	4887 (60)	1.12 (0.84–1.49)	1.14 (0.86–1.53)	1.15 (0.86–1.54)
Increasing	2089 (29)	1.23 (0.83–1.81)	1.25 (0.84–1.84)	1.25 (0.85–1.85)
≥50 years^a	55,784 (553)
Low	3355 (26)	0.70 (0.46–1.05)	0.70 (0.47–1.05)	0.69 (0.46–1.04)
Moderate	20,067 (224)	1.00	1.00	1.00
High	23,252 (228)	0.89 (0.74–1.07)	0.90 (0.75–1.08)	0.91 (0.75–1.09)
Decreasing	69,55 (59)	0.76 (0.57–1.01)	0.79 (0.59–1.05)	0.80 (0.60–1.07)
Increasing	2155 (16)	0.75 (0.46–1.23)	0.75 (0.46–1.23)	0.75 (0.46–1.23)

Notes: ^aSubcohorts are labelled by age at baseline. ^bClass-specific sample size (n) and number of cases (cases). ^cModel 0: Cox proportional hazards model stratified by year of recruitment, and with age as time scale. ^dModel 1: model 0 + education and smoking status. ^eModel 2: model 1 + hair color, ambient ultraviolet radiation of residence and height.