Table 5.
Cox proportional hazard ratios (95% confidence intervals) for overall and specific cancer incidence and cancer related deaths among women in the Nurses’ Health Study with light hair color according to cumulative dose of permanent hair dye use
| Types of cancer | Cumulative dose (women with light hair color) | Per 50 time increment | P value for trend‡ | |||||
|---|---|---|---|---|---|---|---|---|
| No of events | Non-user | 1-99 times | 100-199 times | ≥200 times | P value for trend† | |||
| All cancers* | 9417 | 1 (reference) | 0.95 (0.90 to 1.00) | 0.98 (0.92 to 1.05) | 1.03 (0.97 to 1.10) | 0.36 | 1.00 (1.00 to 1.01) | 0.59 |
| All solid cancers* | 8708 | 1 | 0.95 (0.90 to 1.00) | 0.97 (0.91 to 1.04) | 1.05 (0.98 to 1.12) | 0.25 | 1.00 (1.00 to 1.01) | 0.59 |
| Basal cell carcinoma§ | 11 334 | 1 | 1.09 (1.04 to 1.15) | 1.03 (0.97 to 1.10) | 1.04 (0.98 to 1.11) | 0.23 | 1.00 (0.99 to 1.01) | 0.96 |
| Cutaneous squamous cell carcinoma§ | 1375 | 1 | 0.97 (0.85 to 1.12) | 1.00 (0.84 to 1.19) | 0.86 (0.72 to 1.03) | 0.15 | 0.98 (0.96 to 1.00) | 0.09 |
| Melanoma§ | 580 | 1 | 1.07 (0.86 to 1.32) | 0.90 (0.68 to 1.20) | 0.96 (0.73 to 1.28) | 0.60 | 0.99 (0.96 to 1.02) | 0.42 |
| Breast cancer¶ | 3902 | 1 | 0.97 (0.89 to 1.05) | 0.99 (0.89 to 1.10) | 1.16 (1.05 to 1.28) | 0.006 | 1.01 (1.00 to 1.02) | 0.02 |
| Breast cancer (ER+)¶** | 2595 | 1 | 0.95 (0.86 to 1.06) | 1.03 (0.91 to 1.17) | 1.08 (0.95 to 1.22) | 0.17 | 1.00 (0.99 to 1.02) | 0.50 |
| Breast cancer (ER−)¶** | 649 | 1 | 0.91 (0.74 to 1.12) | 0.85 (0.64 to 1.11) | 1.31 (1.04 to 1.64) | 0.07 | 1.02 (1.00 to 1.04) | 0.03 |
| Breast cancer (PR+)¶** | 2148 | 1 | 0.88 (0.79 to 0.99) | 1.00 (0.87 to 1.15) | 1.07 (0.94 to 1.23) | 0.25 | 1.01 (0.99 to 1.02) | 0.47 |
| Breast cancer (PR−)¶** | 1003 | 1 | 1.06 (0.90 to 1.25) | 1.00 (0.81 to 1.23) | 1.24 (1.02 to 1.49) | 0.06 | 1.02 (1.00 to 1.03) | 0.07 |
| Breast cancer (ER+/PR+)¶** | 2079 | 1 | 0.88 (0.79 to 0.99) | 1.00 (0.87 to 1.16) | 1.08 (0.94 to 1.24) | 0.21 | 1.01 (0.99 to 1.02) | 0.48 |
| Breast cancer (ER+/PR−)¶** | 441 | 1 | 1.28 (1.01 to 1.62) | 1.20 (0.89 to 1.61) | 1.06 (0.78 to 1.45) | 0.60 | 1.00 (0.97 to 1.03) | 0.90 |
| Breast cancer (ER−/PR−)¶** | 561 | 1 | 0.91 (0.72 to 1.14) | 0.85 (0.64 to 1.14) | 1.38 (1.09 to 1.76) | 0.03 | 1.02 (1.00 to 1.05) | 0.02 |
| Ovarian cancer†† | 509 | 1 | 0.89 (0.70 to 1.13) | 1.21 (0.93 to 1.57) | 1.24 (0.95 to 1.61) | 0.048 | 1.02 (0.99 to 1.04) | 0.16 |
| Colorectal cancer‡‡ | 991 | 1 | 1.00 (0.85 to 1.18) | 0.96 (0.78 to 1.19) | 1.17 (0.97 to 1.42) | 0.17 | 1.01 (0.99 to 1.02) | 0.43 |
| Bladder cancer§§ | 260 | 1 | 0.99 (0.72 to 1.37) | 1.00 (0.67 to 1.49) | 1.34 (0.94 to 1.90) | 0.14 | 1.00 (0.96 to 1.04) | 0.99 |
| Kidney cancer | 190 | 1 | 1.22 (0.85 to 1.74) | 0.95 (0.58 to 1.54) | 1.15 (0.74 to 1.81) | 0.70 | 0.99 (0.93 to 1.04) | 0.59 |
| Lung cancer | 1017 | 1 | 0.95 (0.81 to 1.11) | 1.08 (0.89 to 1.31) | 0.90 (0.74 to 1.11) | 0.56 | 0.99 (0.97 to 1.01) | 0.30 |
| Brain cancer | 100 | 1 | 0.43 (0.23 to 0.79) | 0.74 (0.39 to 1.41) | 0.52 (0.25 to 1.10) | 0.08 | 0.93 (0.84 to 1.03) | 0.15 |
| All hematopoietic cancers | 709 | 1 | 0.92 (0.76 to 1.11) | 1.04 (0.83 to 1.31) | 0.89 (0.70 to 1.14) | 0.52 | 1.00 (0.98 to 1.02) | 0.95 |
| All non-Hodgkin lymphomas | 510 | 1 | 0.90 (0.72 to 1.14) | 0.99 (0.75 to 1.31) | 0.86 (0.64 to 1.15) | 0.39 | 1.00 (0.97 to 1.03) | 0.93 |
| T cell lymphoma | 15 | 1 | 1.97 (0.58 to 6.71) | 2.11 (0.50 to 8.91) | 0.66 (0.08 to 5.61) | 0.90 | 0.94 (0.76 to 1.17) | 0.57 |
| Diffuse large B cell lymphoma | 79 | 1 | 0.77 (0.42 to 1.41) | 1.03 (0.51 to 2.05) | 0.90 (0.44 to 1.86) | 0.87 | 1.03 (0.96 to 1.09) | 0.44 |
| Follicular lymphoma | 87 | 1 | 1.30 (0.78 to 2.17) | 0.69 (0.31 to 1.56) | 1.23 (0.64 to 2.35) | 0.84 | 1.02 (0.99 to 1.05) | 0.27 |
| Chronic lymphocytic leukemia/small lymphocytic lymphoma | 111 | 1 | 0.54 (0.31 to 0.93) | 0.77 (0.41 to 1.43) | 0.62 (0.32 to 1.20) | 0.14 | 0.95 (0.88 to 1.04) | 0.28 |
| Hodgkin lymphoma¶¶ | 31 | 1 | 0.62 (0.22 to 1.71) | 0.83 (0.24 to 2.86) | 0.72 (0.21 to 2.47) | 0.60 | 1.01 (0.90 to 1.14) | 0.85 |
| Multiple myeloma¶¶ | 108 | 1 | 1.18 (0.73 to 1.91) | 1.20 (0.67 to 2.13) | 0.99 (0.53 to 1.87) | 0.90 | 0.99 (0.93 to 1.05) | 0.69 |
| Myeloid leukemias | 64 | 1 | 0.75 (0.38 to 1.48) | 0.85 (0.37 to 1.92) | 1.29 (0.61 to 2.70) | 0.60 | 1.03 (0.95 to 1.12) | 0.41 |
| Cancer related death*** | 1801 | 1 | 0.93 (0.83 to 1.05) | 0.91 (0.78 to 1.06) | 0.98 (0.85 to 1.14) | 0.62 | 1.00 (0.98 to 1.01) | 0.59 |
ER=estrogen receptor; PR=progesterone receptor.
All models were adjusted for age, follow-up cycle, race, natural hair color, cumulative average BMI, BMI at age 18, smoking status, pack years of smoking, and alcohol intake. In analyses stratified by natural hair color, models were not further adjusted for natural hair color. Included participants whose natural hair color was red, blond, and light brown. Cumulative dose of permanent hair dye use was calculated by multiplying average frequency of use (times per year) by duration of use (years).
Not including basal cell carcinoma and cutaneous squamous cell carcinoma.
P value for trend was calculated by using the mid-point of each category of cumulative dose in times.
P value for trend was calculated by using cumulative dose in times as continuous variable.
Models were additionally adjusted for childhood reaction to sun, lifetime blistering sunburns, number of moles on arms, and cumulative ultraviolet flux since baseline.
Models were additionally adjusted for menopausal status, postmenopausal hormone use, oral contraceptive use, adolescent body size, age at menarche, age at first birth, parity, breastfeeding, first degree family history of breast cancer, history of benign breast disease, and current mammography use.
Hormone receptor status was not available for all the breast cancer cases.
Models were additionally adjusted for menopausal status, postmenopausal hormone use, age at menarche, oral contraceptive use, and parity.
Models were additionally adjusted for physical activity, menopausal status, postmenopausal hormone use, family history of colorectal cancer, history of diabetes mellitus, screening colonoscopy or sigmoidoscopy in the previous two years, regular use of aspirin, regular use of non-aspirin non-steroidal anti-inflammatory drugs, multivitamin use, total calorie intake, red or processed meat intake, and intake of fiber, folate, calcium, and vitamin D.
Models were additionally adjusted for total fluid intake.
Models were additionally adjusted for regular use of aspirin.
Models were additionally adjusted for physical activity, menopausal status, postmenopausal hormone use, parity, regular use of aspirin, regular use of non-aspirin non-steroidal anti-inflammatory drugs, multivitamin use, total calories intake, history of hypertension, history of hypercholesterolemia, and history of diabetes mellitus.