Table 3.
Associations of estimated total vitamin D intake with lung cancer risk by histological subtype of tumorb
| Total Vitamin D Intake (IU/d) |
||||||
|---|---|---|---|---|---|---|
| Per 100 IU | <200 | 200 to <400 | 400 to <600 | ≥600 | P-trend | |
| Non-small cell lung cancerc | ||||||
| All participants | ||||||
| No. Cases/p-y in subcohort | 476/8,107 | 181/2,871 | 126/2,286 | 97/1,688 | 72/1,262 | |
| HR (95% CI) | 0.95 (0.88-1.03) | 1.00 (Ref) | 0.69 (0.47–1.01) | 0.77 (0.49-1.22) | 0.68 (0.39-1.17) | 0.16 |
| Current smokers | ||||||
| No. Cases/p-y in subcohort | 324/4,298 | 121/1,650 | 79/1,228 | 69/854 | 55/566 | |
| HR (95% CI) | 0.98 (0.89-1.08) | 1.00 (Ref) | 0.62 (0.40-1.01) | 0.73 (0.39-1.35) | 0.92 (0.46-1.87) | 0.60 |
| Former smokersa | ||||||
| No. Cases/p-y in subcohort | 152/3,809 | 60/1,221 | 47/1,058 | 28/834 | 17/696 | |
| HR (95% CI) | 0.89 (0.78-1.02) | 1.00 (Ref) | 1.05 (0.56-1.98) | 0.80 (0.37-1.72) | 0.36 (0.13-0.96) | 0.08 |
| Adenocarcinoma | ||||||
| All participants | ||||||
| No. Cases/p-y in subcohort | 198/7,965 | 81/2,806 | 52/2,254 | 38/1,667 | 27/1,238 | |
| HR (95% CI) | 1.01 (0.91-1.11) | 1.00 (Ref) | 0.80 (0.50–1.29) | 0.96 (0.54-1.70) | 0.97 (0.48-1.95) | 0.88 |
| Current smokers | ||||||
| No. Cases/p-y in subcohort | 132/4,193 | 50/1,615 | 33/1,196 | 26/840 | 23/542 | |
| HR (95% CI) | 1.05 (0.92-1.19) | 1.00 (Ref) | 0.82 (0.44-1.52) | 0.92 (0.43-1.97) | 1.47 (0.61-3.58) | 0.58 |
| Former smokersa | ||||||
| No. Cases/p-y in subcohort | 66/3,772 | 31/1,190 | 19/1,058 | 12/828 | 4/696 | |
| HR (95% CI) | 0.95 (0.78-1.15) | 1.00 (Ref) | 1.12 (0.49-2.59) | 0.94 (0.34-2.59) | 0.42 (0.09-1.87) | 0.45 |
| Squamous cell carcinoma | ||||||
| All participants | ||||||
| No. Cases/p-y in subcohort | 143/7,987 | 49/2,817 | 41/2,257 | 28/1,662 | 25/1,251 | |
| HR (95% CI) | 0.94 (0.84-1.07) | 1.00 (Ref) | 0.68 (0.38–1.21) | 0.70 (0.35-1.43) | 0.65 (0.28-1.51) | 0.30 |
| Current smokers | ||||||
| No. Cases/p-y in subcohort | 104/4,206 | 37/1,611 | 28/1,204 | 20/837 | 19/554 | |
| HR (95% CI) | 0.97 (0.83-1.12) | 1.00 (Ref) | 0.62 (0.30-1.27) | 0.65 (0.26-1.62) | 0.86 (0.31-2.43) | 0.64 |
| Former smokersa | ||||||
| No. Cases/p-y in subcohort | 39/3,781 | 12/1,207 | 13/1,053 | 8/825 | 6/696 | |
| HR (95% CI) | 0.86 (0.68-1.07) | 1.00 (Ref) | 0.97 (0.32-2.88) | 0.74 (0.20-2.81) | 0.33 (0.07-1.62) | 0.18 |
| Small-cell lung cancer | ||||||
| All participants | ||||||
| No. Cases/p-y in subcohort | 116/7,919 | 38/2,779 | 36/2,253 | 23/1,645 | 19/1,242 | |
| HR (95% CI) | 1.08 (0.96-1.22) | 1.00 (Ref) | 0.99 (0.55–1.79) | 1.13 (0.54-2.34) | 1.33 (0.56-3.18) | 0.51 |
| Current smokers | ||||||
| No. Cases/p-y in subcohort | 88/4,155 | 28/1,597 | 30/1,185 | 17/827 | 13/546 | |
| HR (95% CI) | 1.10 (0.95-1.28) | 1.00 (Ref) | 1.16 (0.58-2.33) | 1.22 (0.49-3.04) | 1.53 (0.54-4.38) | 0.45 |
| Former smokersa | ||||||
| No. Cases/p-y in subcohort | 28/3,764 | 10/1,181 | 6/1,068 | 6/818 | 6/697 | |
| HR (95% CI) | 1.07 (0.85-1.34) | 1.00 (Ref) | 0.35 (0.08-1.50) | 0.64 (0.15-2.76) | 0.88 (0.17-4.67) | 0.95 |
Abbreviations: CI, confidence interval; HR, hazard ratio; p-y, person-years; ref, reference.
P-interaction between total vitamin D intake and smoking status: 0.003 for non-small cell lung cancer, 0.001 for adenocarcinoma, 0.21 for squamous cell carcinoma, and 0.45 for small-cell lung cancer. The P-values were obtained by Wald tests of the cross-product term of total vitamin D intake categories and smoking status (both ordinal variables; Wald test).
Adjusted for age, study center, race/ethnicity, education, enrolled as asbestos exposure worker, number of years in high-risk trade, smoking status, smoking pack-years, body mass index, energy intake, total vitamin A intake, and CARET active intervention (time-dependent covariate with a 3-year extended effect post-intervention).
Non-small cell lung cancer included adenocarcinoma, squamous cell carcinoma, and non-small cell lung cancer not otherwise specified or subtypes other than small-cell lung cancer.