Study characteristics and main results of epidemiologic studies investigating the association between vitamin D and survival in patients with colorectal cancer
| Overall mortality | CRC-specific mortality | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| First author, year, country | Population | Follow-up | Time point blood draw | 25(OH)D (nmol/L) | HR (95% CI) | P for trend | 25(OH)D (nmol/L) | HR (95% CI) | P for trend | Confounders |
| Ng, 2008, United States (64) | 304 CRC cases | Median 6.5 years | Prediagnosis (median 6 years before diagnosis) | Quartile 1a | 1.0 | 0.02 | Quartile 1a | 1.0 | 0.23 | Age at diagnosis, sex, season of blood collection, cancer stage, grade of tumor differentiation, location of primary tumor, year of diagnosis, BMI at diagnosis, postdiagnosis physical activity |
| Mean age: 68 | Quartile 2 | 0.81 (0.49–1.35) | Quartile 2 | 0.76 (0.41–1.42) | ||||||
| Stage: I–IV 123 deaths, 96 CRC-specific deaths | Quartile 3 | 0.81 (0.48–1.37) | Quartile 3 | 1.04 (0.58–1.89) | ||||||
| Quartile 4 | 0.52 (0.29–0.94) | Quartile 4 | 0.61 (0.31–1.19) | |||||||
| Fedirko, 2012, Western Europe (EPIC) (65) | 1,201 CRC cases | Mean 6.1 years | Prediagnosis (on average 3.8 years before diagnosis) | Quintile 1 (<36.3) | 1.0 | <0.01 | Quintile 1 (<36.3) | 1.0 | 0.04 | Age at diagnosis, sex, season of blood collection, cancer stage, grade of tumor differentiation, location of primary tumor, year of diagnosis, BMI, physical activity, smoking status, and stratified by country of residence |
| Mean age: 62 | Quintile 2 (36.4–48.6) | 0.82 (0.63–1.07) | Quintile 2 (36.4–48.6) | 0.76 (0.56–1.02) | ||||||
| Stage: I–IV 541 deaths, 444 CRC-specific deaths | Quintile 3 (48.7–60.5) | 0.91 (0.70–1.18) | Quintile 3 (48.7–60.5) | 0.93 (0.69–1.24) | ||||||
| Quintile 4 (60.6–76.8) | 0.78 (0.59–1.03) | Quintile 4 (60.6–76.8) | 0.78 (0.58–1.06) | |||||||
| Quintile 5 (>76.8) | 0.67 (0.50–0.88) | Quintile 5 (>76.8) | 0.69 (0.50–0.93) | |||||||
| Mezawa, 2010, Japan (66) | 257 CRC cases | Median 2.7 years | Peri-operative | Quartile 1 (7.5–17.5) | 0.50 (0.16–1.54) | NA | Continuous per 2.5 nmol/L | 0.98 (0.89–1.08) | NA | Age at diagnosis, sex, calendar month of blood sampling, cancer stage, residual tumor after surgery, time period of surgery, location of tumor, adjuvant chemotherapy, number of lymph nodes with metastasis |
| Mean age: 65 | Quartile 2 (20–25) | 0.55 (0.18–1.65) | ||||||||
| Stage: I–IV 39 deaths, 30 CRC-specific deaths | Quartile 3 (27.5–37.5) | 1.0 | ||||||||
| Quartile 4 (40–90) | 0.16 (0.04–0.63) | |||||||||
| Tretli, 2012, Norway (67) | 52 colon cancer cases | From 1973–2005 until December 2008 | Postdiagnosis (median 30.5 days after diagnosis) | Quartile 1 (<46) | 1.0 | 0.23 | Quartile 1 (<44) | 1.0 | 0.16 | Sex, age at diagnosis, season of blood sampling |
| Median age: 59 | Quartile 2 (46–61) | 0.48 (0.18–1.29) | Quartile 2 (45–56) | 0.46 (0.15–1.48) | ||||||
| Stage: I–IV 26 deaths | Quartile 3 (62–81) | 0.61 (0.23–1.59) | Quartile 3 (57–77) | 0.73 (0.25–2.15) | ||||||
| Quartile 4 (>81) | 0.40 (0.10–1.60) | Quartile 4 (>77) | 0.20 (0.04–1.10) | |||||||
| Ng, 2011, United States/Canada (68) | 515 CRC cases | Median 5.1 years | Post diagnosis, but before chemotherapy | Quartile 1 (5.8–32.8) | 1.0 | 0.55 | NA | NA | NA | Age, sex, season of blood collection, treatment arm, metastatic sites, BMI, baseline performance status |
| Mean age: 61 | Quartile 2 (33–49.8) | 0.78 (0.60–1.02) | ||||||||
| Stage: IV 475 deaths | Quartile 3 (50–67.8) | 1.13 (0.87–1.47) | ||||||||
| Quartile 4 (68–188.5) | 0.94 (0.72–1.23) | |||||||||
| Zgaga, 2014, Scotland (9) | 1,598 CRC cases | Median 8.9 years | Postoperatively (median 105 days after treatment) | Tertile 1 (<18.1) | 1.0 | 0.003 | Tertile 1 (<18.1) | 1.0 | 0.009 | Season of blood collection, tumor site, surgery, time between definitive treatment and sampling, BMI, level of physical activity |
| Mean age: 62 | Tertile 2 (18.2–33.1) | 0.81 (0.65–1.01) | Tertile 2 (18.2–33.1) | 0.86 (0.66–1.13) | ||||||
| Stage: I–III 531 deaths, 363 CRC-specific deaths | Tertile 3 (>33.2) | 0.70 (0.55–0.89) | Tertile 3 (>33.2) | 0.68 (0.50–0.90) | ||||||
NOTE: Vitamin D levels reported in ng/mL were converted into nmol/L using a conversion factor (1 ng/mL = 2.5 nmol/L).
Abbreviations: CRC, colorectal cancer; BMI, body mass index; NA, not available; EPIC, European Prospective Investigation into Cancer and Nutrition.
↵aQuartile ranges differ per laboratory run (3 runs). Quartile 1: 22.8–47.0, 15.0–48.5, 25.8–56.5; Quartile 2: 47.3–59.3, 51.3–64.0, 57.0–67.8; Quartile 3: 60.0–71.3, 64.3–83.5, 68.0–82.8; Quartile 4: 72.5–175.0, 84.3–142.0, 83.5–138.5.