Table 4.
Adjusted hazard ratios and 95% confidence intervals for the associations of breast cancer risk by quartiles of gram per 1,000 kcal of red meat consumed in categories of cooking methods and doneness, as well as by quartiles of meat mutagens
| Characteristic | Quartile 1 | Quartile 2 | Quartile 3 | Quartile 4 | P for trend |
|---|---|---|---|---|---|
| Cooking practices and doneness | |||||
| Grilled red meatb | |||||
| Median (range) (g per 1,000 kcal) | 0 (0.0) | 1.0 (>0.0–1.8) | 3.5 (>1.8–5.9) | 11.7 (>5.9–160) | |
| No. of cases (person-years) | 483 (83,014) | 297 (53,297) | 395 (69,148) | 356 (69,643) | |
| HR (95% CI) | 1.0 (ref) | 0.99 (0.85–1.14) | 1.02 (0.89–1.17) | 0.89 (0.77–1.03) | 0.08 |
| Medium well done, well done, very well done, and/or charred red meat |
|||||
| Median (range) (g per 1,000 kcal) | 0 (0.0) | 1.0 (>0.0–1.8) | 3.4 (>1.8–5.7) | 10.9 (>5.7–135.9) | |
| No. of cases (person-years) | 490 (86,316) | 292 (51,677) | 384 (68,643) | 365 (68,465) | |
| HR (95% CI) | 1.0 (ref) | 1.02 (0.88–1.18) | 1.02 (0.89–1.16) | 0.97 (0.84–1.12) | 0.57 |
| Grilled and medium well done, well done, very well done, and/or charred red meat |
|||||
| Median (range) (g per 1,000 kcal) | 0 (0.0) | 1.4 (>0–3.1) | 6.6 (>3.1–135.9) | ||
| No. of cases (person-years) | 831 (143,595) | 331 (9,522) | 369 (10,469) | ||
| HR (95% CI) | 1.0 (ref) | 0.96 (0.84–1.09) | 0.98 (0.87–1.11) | 0.82 | |
| Meat mutagens | |||||
| DiMeIQx, 2-Amino-3,4,8- trimethylimidazo[4,5-f] quinoxaline |
|||||
| Median (range), ng per day | 0.0 (0) | 0.3 (>0–0.5) | 0.8 (>0.5–1.6) | 2.9 (>1.6–97.6) | |
| No. of cases (person-years) | 533 (97.099) | 216 (40,913) | 393 (65,245) | 394 (72,664) | |
| HR (95% CI) | 1.00 (ref) | 1.00 (0.85–1.17) | 1.13 (0.99–1.29) | 1.01 (0.88–1.15) | 0.94 |
| MeIQx, 2-Amino-3,8-dimethylimidazo[4,5- f] quinoxaline |
|||||
| Median (range), ng per day | 0.3 (0–2.4) | 5.2 (>2.4–9.7) | 15.5 (>9.7–23.9) | 41.8 (>23.9–754.8) | |
| No. of cases (person-years) | 356 (69,099) | 373 (69,305) | 431 (68,718) | 376 (68.799) | |
| HR (95% CI) | 1.00 (ref) | 1.05 (0.91–1.22) | 1.24 (1.07–1.43) | 1.07 (0.92–1.25) | 0.51 |
| PhIP, 2-Amino-1-methyl-6-phenylimidazo (4,5-b) pyridine |
|||||
| Median (range), ng per day | 0.0 (0–6.4) | 12.3 (>6.4–18.3) | 30.8 (>18.3–47.7) | 88.6 (>47.7–3,417.23) | |
| No. of cases (person-years) | 363 (69,507) | 385 (67,983) | 424 (73,343) | 364 (65,089) | |
| HR (95% CI) | 1.00 (ref) | 1.10 (0.95–1.27) | 1.13 (0.98–1.30) | 1.08 (0.93–1.26) | 0.61 |
| B[a]P, benzo[a]pyrene | |||||
| Median (range), ng per day | 0.0 (0–0.1) | 0.6 (>0.1–3.6) | 11.7 (>3.6–27.4) | 51.0 (>27.4–553.4) | |
| No. of cases (person-years) | 403 (68,845) | 396 (68,350) | 347 (68,917) | 390 (69,809) | |
| HR (95% CI) | 1.00 (ref) | 0.99 (0.86–1.14) | 0.92 (0.79–1.06) | 1.00 (0.87–1.16) | 0.80 |
| Heme iron | |||||
| Median (range), µg | 0 (0–28.5) | 62.6 (28.5–97.4) | 136.4 (97.4–193.7) | 297.2 (193.8–1,774.8) | |
| No. of cases (person-years) | 354 (68,390) | 385 (69,624) | 383 (67,871) | 414 (70,037) | |
| HR (95% CI) | 1.00 (ref) | 1.09 (0.93–1.26) | 1.09 (0.94–1.26) | 1.11 (0.96–1.29) | 0.24 |
Abbreviations: HR, hazard ratio; 95% CI, 95% confidence interval; ng, nanogram; g, gram.
All models are adjusted for age (as the primary time scale), race/ ethnicity (non-Hispanic White, non-Hispanic Black, or other), household income (< $49,999, $50,000-$99,999, or ≥$100,000), educational attainment (high school degree or less, some college, or college degree or higher), baseline menopausal status (binary), body mass index (BMI; continuous), interaction term between baseline menopausal status and BMI, waist-to-hip ratio (continuous), total energy intake (kcal/day), consumption of vegetables (quintiles), consumption of fruit (quintiles), percent calories from fat (quartiles), dairy consumption (quartiles), number of relatives diagnosed with breast cancer before the age of 50 (0, 1, or ≥2), lifetime duration of breastfeeding (none and tertiles among women with any breastfeeding, wk), hormone therapy (none, estrogen only, or both estrogen and progesterone), parity (0, 1, 2, or ≥3 births), birth control pill use (never, former, or current), alcohol consumption (never, former, current <1 drink/day, current 1–1.9 drinks/day, or current ≥2 drinks/day), total MET-hours of leisure-time physical activity per week (quintiles), and smoking status (≥20 pack years, <20 and ≥10 pack years, < 10 and > 0 pack years, or never smoker).
Includes steak, pork chop, and hamburger.