Cancer Res Treat.  2018 Apr;50(2):551-561. 10.4143/crt.2017.189.

Evaluation of the Benefit of Radiotherapy in Patients with Occult Breast Cancer: A Population-Based Analysis of the SEER Database

• Kim BH
• Kwon J
• Kim K

• KMID: 2411143
• DOI: http://doi.org/10.4143/crt.2017.189

Abstract

PURPOSE
Few studies for occult breast cancer (OBC) have evaluated the effect of radiotherapy (RT) after mastectomy or axillary lymph node dissection (ALND) with/without breast surgery. Therefore, we investigated clinicopathologic factors of OBC with the impact of postoperative RT to determine its prognostic significance using large population-based data.
MATERIALS AND METHODS
We performed a retrospective cohort study using the Surveillance, Epidemiology, and End Results (SEER) database from 1983 to 2013. A total of 1,045 eligible patients with OBC were identified. We compared overall survival (OS) using Cox proportional hazards regression with propensity score matching after verifying an imbalance of prognosticators between RT group (n=518) and non-RT group (n=479).
RESULTS
Patients with age < 70 (p=0.033), married marital status (p < 0.001), undergoing ALND (p < 0.001), more examined lymph nodes (LNs) (p < 0.001), and more metastatic LNs (p < 0.001) were more likely to receive RT. Multivariate analysis after propensity score matching (n=798) showed that patients treated with RT survived significantly longer than those without RT (5-year OS, 81.5% vs. 78.3%; p=0.014). A significantly prolonged OS was observed when RT was given to patients treated with mastectomy (p=0.033), those treated with ALND (p=0.036), or those with more than seven metastatic LNs (p=0.016).
CONCLUSION
RT may offer survival benefit in OBC even after mastectomy or ALND, especially in patients with more than seven metastatic LNs. Further prospective studies are needed to validate these findings.

Keyword

Occult breast cancer; Radiotherapy; SEER program

MeSH Terms

Breast Neoplasms*
Breast*
Cohort Studies
Epidemiology
Humans
Lymph Node Excision
Lymph Nodes
Marital Status
Mastectomy
Multivariate Analysis
Propensity Score
Prospective Studies
Radiotherapy*
Retrospective Studies
SEER Program

Figure

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  Fig. 1. Kaplan-Meier curve of overall survival in propensity score matched cohort according to the axillary lymph node dissection (ALND) (A), radiotherapy (RT) (B), and type of breast operation (C). ALNS, axillary lymph node sampling.

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  Fig. 2. Hazard ratio and 95% confidence interval for overall survival according to the receipt of radiotherapy (RT) in the subgroup of patients for each characteristic. ER, estrogen receptor; PR, progesterone receptor; LN, lymph node; ALNS, axillary lymph node sampling; ALND, axillary lymph node dissection.

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  Fig. 3. Kaplan-Meier curve of overall survival in propensity score matched cohort according to the receipt of radiotherapy (RT) in the subgroup of patients treated with mastectomy (A) and axillary lymph node dissection (ALND) (B).

Reference

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