Table 3. Subgroup analyses for the effect of PMRT on the 5-year OS rate in the primary analysis.
| Factors | 5-year OS Rate (%) | P | |
|---|---|---|---|
| No PMRT | PMRT | ||
| Age | |||
| ≤40 | 90.2 | 86.7 | 0.136 |
| 41-60 | 82.8 | 85.4 | 0.151 |
| >60 | 67.8 | 78.9 | 0.053 |
| Clinical AJCC stage | |||
| II | 83.9 | 86.5 | 0.424 |
| IIIA | 86.8 | 89.5 | 0.247 |
| IIIB/IIIC | 71.2 | 79.3 | 0.027 |
| Clinical T-stage | |||
| T1/T2 | 86.0 | 87.8 | 0.329 |
| T3/T4 | 76.6 | 82.8 | 0.025 |
| Clinical N-stage | |||
| N1 | 81.7 | 84.8 | 0.191 |
| N2/N3 | 81.5 | 84.0 | 0.359 |
| Pathologic T-stage (after NAC) | |||
| T0/Tis | 86.9 | 86.0 | 0.891 |
| T1/T2 | 78.0 | 83.6 | 0.041 |
| Hormone receptor* | |||
| Negative | 82.6 | 83.4 | 0.587 |
| Positive | 82.9 | 87.6 | 0.178 |
Abbreviations: PMRT, postmastectomy radiotherapy; OS, overall survival; AJCC, American Joint Committee on Cancer (fifth or sixth edition); NAC, neoadjuvant chemotherapy
*
We created a joint hormone receptor status using estrogen receptor (ER) and progesterone receptor (PR) status. Those with either ER or PR positive status (ER or PR positive groups included those with borderline results) were grouped as hormone receptor positive, and those with ER and PR negative status were grouped as hormone receptor negative.