Table 2.
Associations between CYP2D6 inhibition and breast cancer recurrence within strata*
| CYP2D6 inhibition category | ER+/TAM+ |
ER−/TAM− |
P§ | ||||
| Case patients/control subjects | Matched OR (95% CI)† | Adjusted OR (95% CI)‡ | Case patients/control subjects | Matched OR (95% CI)† | Adjusted OR (95% CI)‡ | ||
| CYP2D6*4 genotype | |||||||
| Two functional alleles | 299/308 | 1 (reference) | 1 (reference) | 167/173 | 1 (reference) | 1 (reference) | |
| One functional allele | 154/159 | 0.99 (0.75 to 1.3) | 0.99 (0.76 to 1.3) | 91/94 | 1.0 (0.72 to 1.5) | 0.91 (0.61 to 1.3) | .72 |
| No functional allele | 41/30 | 1.4 (0.81 to 2.3) | 1.4 (0.84 to 2.3) | 19/13 | 1.5 (0.68 to 3.2) | 1.3 (0.60 to 2.9) | .88 |
| CYP2D6*4 genotype | |||||||
| Two functional alleles | 299/308 | 1 (reference) | 1 (reference) | 167/173 | 1 (reference) | 1 (reference) | |
| Less than two functional alleles | 195/189 | 1.0 (0.81 to 1.4) | 1.1 (0.81 to 1.4) | 110/107 | 1.1 (0.77 to 1.7) | 0.95 (0.66 to 1.4) | .54 |
| SSRI prescription | |||||||
| Never | 265/268 | 1 (reference) | 1 (reference) | 170/162 | 1 (reference) | 1 (reference) | |
| Ever | 47/48 | 0.95 (0.62 to 1.5) | 0.91 (0.58 to 1.4) | 17/23 | 0.71 (0.37 to 1.4) | 0.80 (0.38 to 1.7) | .77 |
| Other CYP2D6 inhibitor | |||||||
| Never | 242/258 | 1 (reference) | 1 (reference) | 149/150 | 1 (reference) | 1 (reference) | |
| Ever | 70/58 | 1.3 (0.86 to 1.9) | 1.4 (0.89 to 2.0) | 38/35 | 1.1 (0.66 to 1.8) | 1.2 (0.66 to 2.2) | .68 |
| CYP2D6 inhibition index | |||||||
| No inhibition | 123/125 | 1 (reference) | 1 (reference) | 80/83 | 1 (reference) | 1 (reference) | |
| Low inhibition | 51/56 | 0.88 (0.56 to 1.4) | 0.91 (0.58 to 1.4) | 34/28 | 1.2 (0.68 to 2.2) | 1.3 (0.68 to 2.5) | .37 |
| Low intermediate | 85/88 | 0.95 (0.64 to 1.4) | 0.91 (0.61 to 1.4) | 48/50 | 0.88 (0.54 to 1.4) | 0.74 (0.42 to 1.3) | .56 |
| High intermediate | 14/11 | 1.3 (0.56 to 2.9) | 1.3 (0.56 to 3.1) | 5/7 | 0.68 (0.19 to 2.5) | 0.70 (0.17 to 2.9) | .46 |
| High inhibition | 25/24 | 0.95 (0.50 to 1.8) | 0.95 (0.5 to 1.8) | 16/11 | 1.5 (0.61 to 3.5) | 1.2 (0.42 to 3.6) | .71 |
The source population consisted of 11 251 female residents of the Jutland Peninsula in Denmark aged 35–69 years who were diagnosed with stage I, II, or III breast cancer between 1985 and 2001. Associations between CYP2D6 inhibition and breast cancer recurrence within strata of women with tumors that expressed the estrogen receptor (ER) and who received at least 1 year of tamoxifen therapy (ER+/TAM+) or women with tumors that did not express the ER and who never received tamoxifen therapy and who survived at least 1 year after diagnosis (ERP−/TAM−). CI = confidence interval; CYP2D6 = cytochrome P450 2D6; OR = odds ratio; SSRI = selective serotonin reuptake inhibitor.
Estimated using conditional logistic regression with conditioning on the matched factors (time to recurrence or control selection, county, menopausal status, and stage).
Estimated using logistic regression with adjustment for time to recurrence or control selection, menopausal status, stage, receipt of chemotherapy, receipt of radiation therapy, and type of surgery.
Two-sided P for test of homogeneity of the adjusted odds ratio in ER+/TAM+ women vs the adjusted odds ratio in ER−/TAM− women.