by Di Zhang, Lixi Li, Fei Ma
The Breast: September 10, 2022
Purpose
Adenoid cystic carcinoma of the breast (ACCB) is a rare
malignancy with a favorable prognosis. Little information exists regarding the
impact of postoperative radiation therapy (RT) on survival outcome in patients
with ACCB. This study aimed to evaluate the clinical significance of
postoperative RT in ACCB.
Methods
Data of patients with ACCB were extracted from the
Surveillance, Epidemiology, and End Results database (2000–2019). Univariate
and multivariable Cox regression analyses were performed to identify prognostic
factors. In addition, a nomogram model was constructed and internally validated
for discrimination and calibration. The value of postoperative RT was
respectively accessed in each risk subgroup according to nomogram-deduced
individualized score.
Results
A total of 689 eligible patients were included in the
analysis. Partial mastectomy was associated with an increased risk of death
compared with partial mastectomy plus postoperative RT (P = 0.020), but total
mastectomy with or without postoperative RT was comparable (P = 0.624). Then,
in-depth analysis was performed for patients receiving breast-conversing
therapy (n = 485, the training set vs. the testing set = 340 vs. 145). Age at
diagnosis, histological grade, and T stage were identified as prognostic
factors for overall survival (OS) (All P < 0.05). A nomogram was
constructed to provide predictive accuracy toward individual OS rates of ACCB
and to divide patients into different risk subgroups. Notably, compared with
non-RT, postoperative RT significantly improved OS in the high-risk subgroup (P = 0.006
for the training set, and P = 0.013 for the overall population) but not in
the low-risk subgroup (P = 0.807 for the training set, and P = 0.293 for
the overall population), suggesting that these patients may be able to exempt
from postoperative RT.
Conclusion
A robust and effective nomogram was developed to predict
prognosis and assist in treatment decisions in patients with ACCB undergoing
partial mastectomy.
