Abstract 99P
Background
MAOB is one of the rarest types of breast tumors which represents less than 0.2% of all breast tumors and is associated with a poor prognosis. Mastectomy or BCs are the best therapeutic techniques in patients with MAOB, but there is a debate about the need for postoperative RT. We aimed to study the effectiveness of postoperative RT for MAOB over a long period.
Methods
Patients with MAOB, who underwent a mastectomy and BCS, were identified through the SEER database from 2000 to 2020. Descriptive analyses were conducted to evaluate the clinical characteristics of patients with MAOB.Cancer-specific survival (CSS) was predestined using the Kaplan Meier and compared using the log rank test. Univariate and multivariate Cox proportional hazards regressions were performed to evaluate the prognostic power of factors on CSS.
Results
A total of 542 women with MAOB were included in this study. Most women 82.8% underwent mastectomy, while 17.2% underwent BCS. postoperative RT was performed in 102 women 18.8%, with 27,29.0% in the BCS group and 75,16.7% in the mastectomy group. Postoperative RT was more likely to be performed in women with adverse risk factors, including larger tumor size in the mastectomy group and higher tumor grade in both groups. lymph node metastasis was unwillingly found in MAOB, only 11 patients had positive lymph node metastasis, and among them, 9 patients underwent mastectomy, and 2 patient underwent BCs. Additionally, lymph node involvement increased the chance of postoperative RT in the mastectomy group. In both groups, the need for postoperative RT decreased as the tumor became more invasive. However, this pattern was less obvious in the BCS group. In multivariate analysis, there weren’t any significant prognostic factors impact on CSS in mastectomy group, postoperative RT (P=0.656). In BCS group, age, tumor size and lymph node metastasis were significant predictive factors on CSS, meantime postoperative RT had no effect on (CSS) (P=0.152).
Conclusions
MAOB patients with more inverse prognostic factors were received postoperativeRT, and CSS was not statistically varied from the non-postoperative RT group, independent of surgical type mastectomy or BCs.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.