Table 3.
Hazard ratio for prostate cancer by disease severity among 31 925 men in the Health Professionals Follow-up Study according to reported ejaculation frequency at different timesa,b
| 0–3 EPM | 4–7 EPM | 8–12 EPM | ≥13 EPM |
p value for trend |
|||||
|---|---|---|---|---|---|---|---|---|---|
| Cases (n) |
MV HR (95% CI) |
Cases (n) |
MV HR (95% CI) |
Cases (n) |
MV HR (95% CI) |
Cases (n) |
MV HR (95% CI) |
||
| Age 20–29 yr | |||||||||
| Low-risk disease | 40 | 0.84 (0.59–1.18) | 160 | 1.00 (Ref) | 407 | 0.91 (0.75–1.09) | 687 | 0.75 (0.63–0.89) | 0.0006 |
| Intermediate-risk disease | 39 | 0.85 (0.60–1.20) | 156 | 1.00 (Ref) | 390 | 0.88 (0.73–1.06) | 664 | 0.73 (0.61–0.88) | 0.0003 |
| High-risk disease | 43 | 0.99 (0.70–1.39) | 142 | 1.00 (Ref) | 435 | 1.13 (0.93–1.36) | 775 | 1.00 (0.84–1.20) | 0.46 |
| Regional/distant metastases | 28 | 1.20 (0.77–1.87) | 70 | 1.00 (Ref) | 186 | 1.01 (0.77–1.33) | 320 | 0.89 (0.68–1.15) | 0.07 |
| Age 40–49 yr | |||||||||
| Low-risk disease | 65 | 0.95 (0.72–1.23) | 347 | 1.00 (Ref) | 502 | 0.88 (0.77–1.01) | 335 | 0.72 (0.61–0.83) | <0.0001 |
| Intermediate-risk disease | 52 | 0.70 (0.52–0.94) | 363 | 1.00 (Ref) | 579 | 0.99 (0.87–1.13) | 401 | 0.83 (0.72–0.96) | 0.11 |
| High-risk disease | 39 | 1.13 (0.80–1.61) | 160 | 1.00 (Ref) | 217 | 0.85 (0.69–1.04) | 188 | 0.89 (0.72–1.11) | 0.17 |
| Regional/distant metastases | 7 | 0.61 (0.27–1.35) | 44 | 1.00 (Ref) | 55 | 0.85 (0.57–1.27) | 51 | 0.96 (0.64–1.45) | 0.65 |
| Year before | |||||||||
| questionnaire (1991) | |||||||||
| Low-risk disease | 365 | 1.05 (0.91–1.21) | 446 | 1.00 (Ref) | 303 | 0.94 (0.81–1.09) | 135 | 0.75 (0.62–0.92) | 0.002 |
| Intermediate-risk disease | 432 | 1.01 (0.89–1.16) | 481 | 1.00 (Ref) | 325 | 1.00 (0.87–1.15) | 157 | 0.89 (0.74–1.07) | 0.27 |
| High-risk disease | 232 | 1.18 (0.96–1.45) | 180 | 1.00 (Ref) | 129 | 1.20 (0.95–1.50) | 63 | 1.12 (0.84–1.51) | 0.94 |
| Regional/distant metastases | 72 | 0.94 (0.64–1.38) | 48 | 1.00 (Ref) | 15 | 0.59 (0.33–1.07) | 22 | 1.82 (1.07–3.10) | 0.19 |
EPM = ejaculations per month; MV = multivariate; HR = hazard ratio; CI = confidence interval; PSA = prostate-specific antigen.
Risk groups are based on National Comprehensive Cancer Network guidelines. Men were assigned to the highest category for which they were eligible: low risk = T1/T2 tumor, PSA <10 ng/ml, Gleason score 6; intermediate risk = T1/T2 tumor, PSA 10–<20 ng/ml, Gleason score 7; High risk = T3 tumor, PSA level 20–<50 ng/ml, Gleason score 8; regional or distant metastases =T4/N1/M1 tumor, PSA >50 ng/ml.
Age-adjusted models are adjusted for age in months and calendar time. Multivariate models are additionally adjusted for: race; family history of prostate cancer; vigorous physical activity (quintiles); body mass index (six categories); height (quintiles); diabetes; marital status; intake of energy, processed meat, tomato sauce, calcium, alcohol, and α-linolenic acid (all quintiles); multivitamin use; smoking (never, quit >10 yrs ago, quit ≤10 yrs ago, current); history of vasectomy; and history of PSA testing.