Participant characteristics
Of the 107 622 participants in 1999–2020 NHANES, there were 28 250 males aged 20 years or older; 45 and 35 of these males were excluded due to unavailable data on PCa history and cigarette use. A total of 28 170 participants representing 104 893 498 US males were included in this analysis (Fig. 1). The mean (SD) age of participants was 46.4 (16.4) years (Table 1); 6976 (14.5%) were Hispanic, 12 464 (68.0%) were non-Hispanic White, and 6030 (10.4%) were non-Hispanic Black. Compared to never smokers, more former smokers but fewer current smokers were aged 60 years or older, married/living with partner, overweight and obesity (all P < 0.05). More former and current smokers had high school or lower education level and low-middle family income than never smokers (all P < 0.05). Fewer former smokers but more current smokers than never smokers were non-Hispanic Black (6.2% vs 13.6% vs 11.4%, P < 0.001). Comparisons of participants’ characteristics between ever smokers and never smokers are shown in Additional file 1.
Table 1
Baseline characteristics of study participantsa
Characteristic | Cigarette use, No. (weighted %) | P valueb |
Total (n = 28170) | Never (n = 12593) | Current (n = 6931) | Former (n = 8646) |
Age, mean (SD), years | 46.4 (16.4) | 43.7 (13.4) | 41.9 (12.5) | 54.2 (14.5) | < 0.001 |
20–39 | 9294 (38.7) | 5114 (44.5) | 2836 (47.7) | 1344 (21.9) | < 0.001 |
40–59 | 8924 (37.8) | 4047 (37.7) | 2537 (39.1) | 2340 (36.8) | |
≥60 | 9952 (23.5) | 3432 (17.8) | 1558 (13.2) | 4962 (41.2) | |
Race | | | | | < 0.001 |
Hispanic | 6976 (14.5) | 3282 (15.9) | 1572 (14.2) | 2122 (12.5) | |
Non-Hispanic White | 12464 (68.0) | 4991 (64.9) | 2952 (65.2) | 4521 (75.4) | |
Non-Hispanic Black | 6030 (10.4) | 2847 (11.4) | 1841 (13.6) | 1342 (6.2) | |
Otherc | 2700 (7.1) | 1473 (7.8) | 566 (7.0) | 661 (5.9) | |
Education level | | | | | < 0.001 |
Less than high school | 7848 (17.7) | 2800 (12.8) | 2477 (26.6) | 2571 (18.1) | |
High school or equivalent | 6727 (25.0) | 2642 (21.2) | 2016 (32.0) | 2069 (25.5) | |
Some college | 7377 (28.9) | 3371 (28.2) | 1790 (30.0) | 2216 (29.0) | |
College graduate or above | 6180 (28.4) | 3762 (37.8) | 639 (11.3) | 1779 (27.3) | |
Marital status | | | | | < 0.001 |
Married/living with partner | 18137 (67.1) | 8157 (68.0) | 3762 (56.4) | 6218 (74.6) | |
Widowed/divorced/separated | 4512 (12.8) | 1506 (9.3) | 1427 (17.6) | 1579 (14.5) | |
Never married | 5267 (20.1) | 2831 (22.7) | 1664 (26.0) | 772 (10.9) | |
Family income | | | | | < 0.001 |
Low income | 4831 (12.7) | 1819 (10.6) | 1830 (21.3) | 1135 (8.5) | |
Middle income | 13565 (48.4) | 5776 (44.5) | 3398 (54.6) | 4435 (50.1) | |
High income | 7017 (38.9) | 3738 (44.9) | 1006 (24.1) | 2273 (41.4) | |
BMI category | | | | | < 0.001 |
Normal | 7072 (26.2) | 3038 (25.0) | 2358 (36.0) | 1676 (20.0) | |
Overweight | 10117 (38.6) | 4548 (39.1) | 2239 (34.7) | 3330 (41.1) | |
Obesity | 8645 (34.1) | 4025 (35.0) | 1695 (27.1) | 2925 (39.4) | |
Underweight | 334 (1.1) | 105 (0.9) | 179 (2.2) | 50 (0.5) | |
SD, standard deviation; BMI, body mass index.
a Accounting for sampling weights.
b Calculated by Chi-square test or one-way analysis of variance.
c Other race/ethnicity includes American Indian or Alaska Native, Native Hawaiian or Pacific Islander, multiple races or ethnicities, or unknown.
Associations between cigarette use and risk of prostate cancer
Table 2 shows that compared to never smokers, an increased risk of PCa was found in former smokers (aOR, 3.54 [95% CI, 1.60–7.79]) and ever smokers (aOR, 2.23 [95% CI, 1.06–4.68]) but not in current smokers (aOR, 1.04 [95% CI, 0.38–2.85]), adjusting for age, race, education level, marital status, family income, BMI, and interaction of age and cigarette use. Dose-response analyses showed that longer smoking duration was associated with an increased risk of PCa in current smokers (aOR, 1.07 [95% CI, 1.03–1.11]) but not in former smokers (aOR, 1.00 [95% CI, 0.99–1.02]), adjusting for age, race, education level, marital status, family income, and BMI.
Table 2
Association of cigarette use with prostate cancer
Exposures | Diagnosed with prostate cancer |
Crude OR (95% CI) | | Adjusted OR (95% CI)b | P for interaction |
Cigarette usea | | | | |
Former smokers | 2.18 (1.78–2.67)*** | 3.54 (1.60–7.79)** | 0.001 |
Current smokers | 0.47 (0.33–0.66)*** | 1.04 (0.38–2.85) | 0.26 |
Ever smokers | 1.40 (1.15–1.69)** | 2.23 (1.06–4.68)* | 0.01 |
Smoking duration, years | | | | |
Former smokers | 1.04 (1.03–1.05)*** | 1.00 (0.99–1.02) | NA |
Current smokers | 1.11 (1.09–1.13)*** | 1.07 (1.03–1.11)*** | NA |
OR, odds ratio; CI, confidence interval; NA, not available
*** P < 0.001, ** P < 0.01, * P < 0.05
a Reference group = never smokers
b Adjusted for age, race, education level, marital status, family income, and body mass index for “Smoking duration”; additionally adjusted for interaction of age and cigarette use for “Cigarette use”.
Table 3 shows that in participants aged 20–59 years, an increased risk of PCa was found in former (aOR, 3.81 [95% CI, 1.69–8.59]) and ever smokers (aOR, 2.77 [95% CI, 1.25–6.13]) but not in current smoker (aOR, 1.43 [95% CI, 0.53–3.87]). In participants aged 60 years or older, current smokers had decreased risks of PCa (aOR, 0.52 [95% CI, 0.32–0.84]) while former smokers (aOR, 0.94 [95% CI, 0.75–1.18]) and ever smokers (aOR, 0.86 [95% CI, 0.69–1.07]) showed neither increased nor decreased PCa risks. Subgroup analyses across varying races, education levels, and family income showed that the increased risk of PCa among ever smokers was only evident in participants of non-Hispanic White race (aOR, 4.10 [95% CI, 1.13–14.88]), in participants with education level of some college or above (aOR, 3.34 [95% CI, 1.52–7.35]), and in participants with high family income (aOR, 2.94 [95% CI, 1.13–7.62]) (Additional file 2).
Table 3
Association of cigarette use with prostate cancer by age groups
Exposuresa | Diagnosed with prostate cancer |
Crude, OR (95% CI) | P | Adjusted OR (95% CI)b | P |
For participants aged 20–59 years |
Former smokers | 3.35 (1.57–7.18) | 0.002 | 3.81 (1.69–8.59) | 0.001 |
Current smokers | 1.14 (0.47–2.78) | 0.78 | 1.43 (0.53–3.87) | 0.48 |
Ever smokers | 2.14 (1.07–4.27) | 0.03 | 2.77 (1.25–6.13) | 0.01 |
For participants aged 60 years or older |
Former smokers | 0.91 (0.74–1.12) | 0.36 | 0.94 (0.75–1.18) | 0.61 |
Current smokers | 0.54 (0.35–0.81) | 0.004 | 0.52 (0.32–0.84) | 0.008 |
Ever smokers | 0.83 (0.68–1.01) | 0.07 | 0.86 (0.69–1.07) | 0.17 |
OR, odds ratio; CI, confidence interval |
a Reference group = never smokers; |
b Adjusted for race, education level, marital status, family income, and body mass index.