Table 2. Overall risk of second cancer, adjusted by age and calendar year at diagnosis, by tumor and patients characteristics, and by therapeutic approach, using risk set sampling.
| Case* (n=305) No. (%) |
Control* (n=1,525) No. (%) |
OR (95% CI) | p-value† | ||
|---|---|---|---|---|---|
| Tumour and patients characteristics | |||||
| Grading | 1-2 | 184 (62) | 968 (66) | 1.00 | |
| 3 | 112 (38) | 500 (34) | 1.21 (0.92-1.59) | 0.174 | |
| Unknown | 9 (3) | 57 (4) | 0.83 (0.42-1.67) | 0.610 | |
| Primary tumor size (T) | T1mic-T1b | 101 (35) | 471 (32) | 1.00 | |
| T1c | 119 (41) | 646 (44) | 0.87 (0.65-1.17) | 0.349 | |
| T2 | 71 (24) | 353 (24) | 0.93 (0.65-1.34) | 0.702 | |
| Unknown | 14 (5) | 55 (4) | 1.26 (0.64-2.44) | 0.503 | |
| ER (%) | ≥ 10 | 233 (80) | 1,212 (82) | 1.00 | |
| < 10 | 62 (20) | 269 (18) | 1.19 (0.88-1.62) | 0.262 | |
| Unknown | 10 (3) | 44 (3) | 1.15 (0.56-2.38) | 0.702 | |
| PR (%) | ≥ 10 | 193 (66) | 954 (65) | 1.00 | |
| < 10 | 101 (34) | 524 (35) | 0.95 (0.73-1.24) | 0.698 | |
| Unknown | 11 (4) | 47 (3) | 1.13 (0.56-2.87) | 0.732 | |
| Ki-67 (%) | < 20 | 185 (63) | 969 (66) | 1.00 | |
| ≥ 20 | 108 (37) | 488 (34) | 1.16 (0.90-1.50) | 0.261 | |
| Unknown | 12 (4) | 68 (5) | 0.92 (0.48-1.74) | 0.793 | |
| HER2‡ | Negative | 115 (78) | 633 (86) | 1.00 | |
| Positive | 32 (22) | 102 (14) | 1.73 (1.10-2.70) | 0.017 | |
| Unknown | 158 (52) | 790 (52) | 1.01 (0.65-1.58) | 0.957 | |
| Genetic predisposition | Sporadic | 277 (91) | 1,403 (93) | 1.00 | |
| Fam. | 19 (6) | 95 (6) | 1.04 (0.62-1.73) | 0.889 | |
| Inher. | 7 (2) | 12 (1) | 3.53 (1.29-9.64) | 0.014 | |
| Unknown | 2 (1) | 15 (1) | 0.69 (0.17-2.82) | 0.601 | |
| Therapeutic approach (mutually exclusive) | |||||
| Surgery alone | No | 277 (91) | 1,409 (91) | 1.00 | |
| Yes | 28 (9) | 116 (9) | 1.19 (0.76-1.86) | 0.440 | |
| Surgery+CHT | No | 283 (93) | 1,459 (96) | 1.00 | |
| Yes | 22 (7) | 66 (4) | 1.76 (1.07-2.91) | 0.026 | |
| Surgery+RT | No | 268 (88) | 1,388 (91) | 1.00 | |
| Yes | 37 (12) | 137 (9) | 1.44 (0.96-2.16) | 0.078 | |
| Surgery+CHT+RT | No | 281 (92) | 1,423 (93) | 1.00 | |
| Yes | 24 (8) | 102 (7) | 1.20 (0.74-1.95) | 0.464 | |
| Surgery+HT | No | 258 (85) | 1,272 (83) | 1.00 | |
| Yes | 47 (15) | 253 (17) | 0.88 (0.61-1.27) | 0.494 | |
| Surgery+RT+HT | No | 227 (74) | 1,127 (74) | 1.00 | |
| Yes | 78 (26) | 398 (26) | 0.98 (0.73-1.31) | 0.878 | |
| Surgery+CHT+HT | No | 282 (92) | 1,375 (90) | 1.00 | |
| Yes | 23 (8) | 150 (10) | 0.74 (0.47-1.16) | 0.188 | |
| Surgery+CHT+RT+HT | No | 259 (85) | 1,224 (80) | 1.00 | |
| Yes | 46 (15) | 301 (20) | 0.72 (0.50-1.03) | 0.074 | |
| Surgery +/-CHT+/-RT+HT | No | 111 (36) | 423 (28) | 1.00 | |
| Yes | 194 (64) | 1,102 (72) | 0.66 (0.50-0.86) | 0.003 | |
| Therapeutic approach | |||||
| Surgery+HT+CHT+/-RT | 69 (23) | 451 (30) | 1.00 | ||
| Surgery alone/Surgery+HT+/-RT | 153 (50) | 769 (50) | 1.30 (0.93-1.83) | 0.125 | |
| Surgery+RT | 37 (12) | 137 (9) | 1.85 (1.15-2.98) | 0.011 | |
| Surgery+CHT | 22 (7) | 66 (4) | 2.24 (1.30-3.85) | 0.004 | |
| Surgery+CHT+RT | 24 (8) | 102 (7) | 1.58 (0.93-2.70) | 0.093 |
OR=odds ratio; CI=confidence interval; ER=estrogen receptor; PR=progesterone receptor; HER2=human epidermal growth factor receptor; Fam.=familial; the woman have at least two first-degree relatives (mother, father, daughter, son, sister, brother) with breast cancer; Inher.=inheritance; mutation of breast cancer gene (BRCA1 or BRCA2); CHT=chemotherapy; RT=radiotherapy; HT=hormone therapy.
*Case control 1:5 matched by age group, stage, year of diagnosis of primary breast cancer, using risk set sampling; Multiple conditional logistic regression where the factors were adjusted by age and calendar year of diagnosis of primary breast cancer; †p-value were two-sided Wald test; ‡HER2 evaluation was routinely performed from 2001.