Table 6.
Clinical and Pathologic Predictors of Germline Mutations in BRCA1/2 and Other Breast Cancer Predisposition Genes*
| Variable | No Mutation (n = 436) | BRCA1/2 Mutation (n = 30)† | Other BC Mutation (n = 19)†* | P | ||||
|---|---|---|---|---|---|---|---|---|
| No. | % | No. | % | No. | % | No Mutation v BRCA1/2 Mutation | No Mutation v Other BC Mutation | |
| Patient characteristic | ||||||||
| Age at BC diagnosis, years | < .01 | .72 | ||||||
| Mean ± SD | 50.7 ± 11.2 | 42.6 ± 9.7 | 51.6 ± 10.9 | |||||
| Median | 49 | 40 | 53 | |||||
| Range | 28-88 | 31-66 | 34-68 | |||||
| ≤ 45 | 150 | 34.4 | 22 | 73.3 | 7 | 36.8 | < .01 | .96 |
| 46-60 | 184 | 42.2 | 6 | 20.0 | 8 | 42.1 | ||
| > 60 | 102 | 23.4 | 2 | 6.7 | 4 | 21.1 | ||
| Ashkenazi Jewish heritage | ||||||||
| Yes | 29 | 6.7 | 7 | 23.3 | 2 | 10.5 | < .01 | .51 |
| No | 407 | 93.3 | 23 | 76.7 | 17 | 89.5 | ||
| History of cancer‡ | ||||||||
| Yes | 37 | 8.5 | 1 | 3.3 | 3 | 15.8 | .32 | .27 |
| No | 399 | 91.5 | 29 | 96.7 | 16 | 84.2 | ||
| BC characteristic | ||||||||
| Subtype | ||||||||
| TNBC | 72 | 16.5 | 12 | 40.0 | 2 | 10.5 | .01 | .11 |
| HR-positive/HER2-negative | 275 | 63.1 | 15 | 50.0 | 9 | 47.4 | ||
| HR-negative/HER2-positive | 33 | 7.6 | 2 | 6.7 | 2 | 10.5 | ||
| HR-positive/HER2-positive | 56 | 12.8 | 1 | 3.3 | 6 | 31.6 | ||
| Histology | ||||||||
| Ductal | 325 | 74.5 | 22 | 73.3 | 10 | 52.6 | .50 | .08 |
| Lobular | 33 | 7.6 | 1 | 3.3 | 2 | 10.5 | ||
| Ductal and lobular | 58 | 13.3 | 4 | 13.3 | 4 | 21.1 | ||
| Other | 20 | 4.6 | 3 | 10.0 | 3 | 15.8 | ||
| Histologic grade§ | ||||||||
| 1 | 57 | 13.1 | 0 | 0.0 | 3 | 15.8 | < .01 | .94 |
| 2 | 167 | 38.4 | 4 | 13.3 | 7 | 36.8 | ||
| 3 | 211 | 48.5 | 26 | 86.7 | 9 | 47.4 | ||
| Stage | ||||||||
| I | 169 | 38.8 | 12 | 40.0 | 4 | 21.1 | .03 | .12 |
| II | 198 | 45.4 | 8 | 26.7 | 9 | 47.4 | ||
| III | 69 | 15.8 | 10 | 33.3 | 6 | 31.6 | ||
| Bilateral disease | ||||||||
| Yes | 8 | 1.8 | 0 | 0.0 | 1 | 5.3 | .45 | .29 |
| No | 428 | 98.2 | 30 | 100.0 | 18 | 94.7 | ||
| Family history of cancer and prior genetic testing | ||||||||
| First-degree relative with any cancer‡‖ | ||||||||
| Yes | 242 | 56.8 | 15 | 50.0 | 12 | 63.2 | .47 | .58 |
| No | 184 | 43.2 | 15 | 50.0 | 7 | 36.8 | ||
| First- or second-degree relative with any cancer‡‖ | ||||||||
| Yes | 356 | 83.6 | 30 | 100.0 | 15 | 78.9 | .02 | .60 |
| No | 70 | 16.4 | 0 | 0.0 | 4 | 21.1 | ||
| First- or second-degree relative with BC or ovarian cancer‡‖ | ||||||||
| Yes | 202 | 47.4 | 22 | 73.3 | 9 | 47.4 | .01 | 1.0 |
| No | 224 | 52.6 | 8 | 26.7 | 10 | 52.6 | ||
| First- or second-degree relative < 50 years of age with BC, ovarian cancer, or male BC‡‖ | ||||||||
| Yes | 71 | 16.7 | 12 | 40.0 | 5 | 26.3 | < .01 | .27 |
| No | 355 | 83.3 | 18 | 60.0 | 14 | 73.7 | ||
Abbreviations: BC, breast cancer; HER2, human epidermal growth factor receptor 2; HR, hormone receptor; SD, standard deviation; TNBC, triple-negative breast cancer.
Three patients with mutations not associated with breast cancer were not included in this analysis.
One patient with BRCA2 and ATM mutations is included with BRCA1/2 Mutation (not with Other BC Mutation).
Excludes in situ cancers and nonmelanoma skin cancers.
Tumor grade was missing for one patient without a mutation.
Ten patients were missing family history information. These patients were excluded from analysis. If age at diagnosis was unavailable, it was conservatively considered to be older than 50 years.