Table 2.
Characteristics of the patients with age at primary breast cancer diagnosis <40 years, radiotherapy vs. no radiotherapy
| Total (n = 325)* | RT after lumpectomy (n = 166) | No RT after mastectomy (n = 115) | RT after mastectomy (n = 42) | p value | |
|---|---|---|---|---|---|
| n (%) | n (%) | n (%) | n (%) | ||
| Age at primary BC | |||||
| <30 years | 55 (16.9) | 29 (17.5) | 19 (16.5) | 7 (16.7) | 0.996 |
| 30–34 years | 115 (35.4) | 59 (35.5) | 39 (33.9) | 15 (35.7) | |
| 35–39 years | 155 (47.7) | 78 (47.0) | 57 (49.6) | 20 (47.6) | |
| Mutation status | |||||
| BRCA1 | 261 (80.3) | 143 (86.1) | 89 (77.4) | 27 (64.3) | 0.004 |
| BRCA2 | 64 (19.7) | 23 (13.9) | 26 (22.6) | 15 (35.7) | |
| Period of primary BC | |||||
| 1980–1989 | 43 (13.2) | 33 (19.9) | 5 (4.4) | 5 (11.9) | <0.001 |
| 1990–1999 | 114 (35.1) | 68 (41.0) | 35 (30.4) | 10 (23.8) | |
| 2000–2013 | 168 (51.7) | 65 (39.2) | 75 (65.2) | 27 (64.3) | |
| Tumor stage | |||||
| Tis | 9 (2.9) | 4 (2.6) | 5 (4.5) | 0 | <0.001 |
| T1 | 179 (58.5) | 95 (60.5) | 70 (63.6) | 14 (35.9) | |
| T2 | 103 (33.7) | 57 (36.3) | 31 (28.2) | 15 (38.5) | |
| T3 | 8 (2.6) | 0 | 3 (2.7) | 5 (12.8) | |
| T4 | 7 (2.3) | 1 (0.6) | 1 (0.9) | 5 (12.8) | |
| Unknown | 19 | 9 | 5 | 3 | |
| Nodal status | |||||
| N0 | 206 (66.0) | 120 (74.5) | 78 (70.3) | 7 (17.9) | <0.001 |
| N1–3 | 106 (34.0) | 41 (25.5) | 33 (29.7) | 32 (82.1) | |
| Unknown | 13 | 5 | 4 | 3 | |
| Histological grade | |||||
| Grade 1 | 6 (2.5) | 2 (1.7) | 2 (2.1) | 2 (6.5) | 0.561 |
| Grade 2 | 45 (18.4) | 21 (17.7) | 17 (18.1) | 7 (22.6) | |
| Grade 3 | 193 (79.1) | 96 (80.7) | 75 (79.8) | 22 (71.0) | |
| Unknown | 81 | 47 | 21 | 11 | |
| Hormone receptor status | |||||
| Positive | 93 (33.1) | 41 (29.5) | 31 (30.7) | 21 (52.5) | 0.020 |
| Negative | 188 (66.9) | 98 (70.5) | 70 (69.3) | 19 (47.5) | |
| Unknown | 44 | 27 | 14 | 2 | |
| HER2 status | |||||
| Positive | 10 (7.6) | 4 (7.8) | 3 (5.5) | 3 (12.0) | 0.592 |
| Negative | 122 (92.4) | 47 (92.2) | 52 (94.5) | 22 (88.0) | |
| Unknown | 193 | 115 | 60 | 17 | |
| (Neo-) adjuvant chemotherapy | |||||
| No | 125 (38.9) | 75 (45.7) | 33 (28.9) | 16 (39.0) | 0.019 |
| Yes | 196 (61.1) | 89 (54.3) | 81 (71.1) | 25 (61.0) | |
| Unknown | 4 | 2 | 1 | 1 | |
| Adjuvant endocrine therapy | |||||
| No | 262 (81.4) | 148 (90.2) | 90 (78.9) | 22 (52.4) | <0.001 |
| Yes | 60 (18.6) | 16 (9.8) | 24 (21.1) | 20 (47.6) | |
| Unknown | 3 | 0 | 1 | 0 | |
| Contralateral risk-reducing mastectomy | |||||
| No | 174 (55.8) | 105 (66.0) | 46 (41.1) | 23 (56.1) | <0.001 |
| Yes | 138 (44.2) | 54 (34.0) | 66 (58.9) | 18 (43.9) | |
| Unknown | 13 | 7 | 3 | 1 | |
| Salpingo-oophorectomy | |||||
| No | 128 (42.8) | 66 (43.7) | 43 (40.6) | 18 (45.0) | 0.825 |
| Yes | 171 (57.2) | 85 (56.3) | 63 (59.4) | 22 (55.0) | |
| Unknown | 26 | 15 | 9 | 2 | |
RT radiotherapy; BC breast cancer
* Data on type of surgery (either lumpectomy or mastectomy) were missing in 2 patients who were treated with radiotherapy