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

Best treatment options for occult breast cancer: A meta-analysis

Objectives

Occult breast cancer (OBC) is a rare malignant breast tumor. Because of the rare cases and limited clinical experience, a huge therapeutic difference has existed all over the world and standardized treatments have yet been established.

Methods

A meta-analysis was conducted using MEDLINE and Embase databases to identify the choice of OBC surgical procedures in all studies: (1) patients undergoing axillary lymph node dissection (ALND) or sentinel lymph node biopsy (SLNB) only; (2) patients undergoing ALND with radiotherapy (RT); (3) patients undergoing ALND with breast surgery (BS); (4) patients undergoing ALND with RT and BS; and (5) patients undergoing observation or RT only. The primary endpoints were mortality rates, the second endpoints were distant metastasis and locoregional recurrence.

Results

Among the 3,476 patients, 493 (14.2%) undergo ALND or SLNB only; 632 (18.2%) undergo ALND with RT; 1483 (42.7%) undergo ALND with BS; 467 (13.4%) undergo ALND RT and BS, and 401 (11.5%) undergo observation or RT only. After comparing the multiple groups, both groups 1 and 3 have higher mortality rates than group 4 (30.7% vs. 18.6%, p < 0.0001; 25.1% vs. 18.6%, p = 0.007), and group 1 has higher mortality rates than groups 2 and 3 (30.7% vs.14.7%, p < 0.00001; 30.7 vs. 19.4%, p < 0.0001). Group (1 + 3) had a prognosis advantage over group 5 (21.4% vs. 31.0%, p < 0.00001). There was no significant difference both in the distant recurrence rates and locoregional rates between group (1 + 3) and group (2 + 4) (21.0% vs. 9.7%, p = 0.06; 12.3% vs. 6.5%, p = 0.26).

Conclusion

On the basis of this meta-analysis, our study indicates that BS including modified radical mastectomy (MRM) and breast-conserving surgery (BCS) combined RT may appear as the optimal surgical approach in patients with OBC. RT cannot prolong both the time of distant metastasis and the local recurrences.

Prognostic Models Using Machine Learning Algorithms and Treatment Outcomes of Occult Breast Cancer Patients

BACKGROUND

Occult breast cancer (OBC) is an uncommon malignant tumor and the prognosis and treatment of OBC remain controversial. Currently, there exists no accurate prognostic clinical model for OBC, and the treatment outcomes of chemotherapy and surgery in its different molecular subtypes are still unknown.

METHODS

The SEER database provided the data used for this study's analysis (2010-2019). To identify the prognostic variables for patients with ODC, we conducted Cox regression analysis and constructed prognostic models using six machine learning algorithms to predict overall survival (OS) of OBC patients. A series of validation methods, including calibration curve and area under the curve (AUC value) of receiver operating characteristic curve (ROC) were employed to validate the accuracy and reliability of the logistic regression (LR) models. The effectiveness of clinical application of the predictive models was validated using decision curve analysis (DCA). We also investigated the role of chemotherapy and surgery in OBC patients with different molecular subtypes, with the help of K-M survival analysis as well as propensity score matching, and these results were further validated by subgroup Cox analysis.

RESULTS

The LR models performed best, with high precision and applicability, and they were proved to predict the OS of OBC patients in the most accurate manner (test set: 1-year AUC = 0.851, 3-year AUC = 0.790 and 5-year survival AUC = 0.824). Interestingly, we found that the N1 and N2 stage OBC patients had more favorable prognosis than N0 stage patients, but the N3 stage was similar to the N0 stage (OS: N0 vs. N1, HR = 0.6602, 95%CI 0.4568-0.9542, p < 0.05; N0 vs. N2, HR = 0.4716, 95%CI 0.2351-0.9464, p < 0.05; N0 vs. N3, HR = 0.96, 95%CI 0.6176-1.5844, p = 0.96). Patients aged >80 and distant metastases were also independent prognostic factors for OBC. In terms of treatment, our multivariate Cox regression analysis discovered that surgery and radiotherapy were both independent protective variables for OBC patients, but chemotherapy was not. We also found that chemotherapy significantly improved both OS and breast cancer-specific survival (BCSS) only in the HR-/HER2+ molecular subtype (OS: HR = 0.15, 95%CI 0.037-0.57, p < 0.01; BCSS: HR = 0.027, 95%CI 0.027-0.81, p < 0.05). However, surgery could help only the HR-/HER2+ and HR+/HER2- subtypes improve prognosis.

CONCLUSIONS

We analyzed the clinical features and prognostic factors of OBC patients; meanwhile, machine learning prognostic models with high precision and applicability were constructed to predict their overall survival. The treatment results in different molecular subtypes suggested that primary surgery might improve the survival of HR+/HER2- and HR-/HER2+ subtypes, however, only the HR-/HER2+ subtype could benefit from chemotherapy. The necessity of surgery and chemotherapy needs to be carefully considered for OBC patients with other subtypes.

Reconceptualizing the clinicopathological features, locoregional therapy and prognostic factors of occult breast cancer in the era of molecular subtyping

To evaluate the clinical features, molecular subtypes, therapeutic strategies, and prognostic factors of occult breast cancer (OBC). Patients with T0-3/N1-3/M0 breast cancer diagnosed in 2010-2018 (n = 114,303, including 691 with OBC) were retrieved from the Surveillance, Epidemiology, and End-Results (SEER) database. The endpoints were overall survival (OS) and breast cancer-specific survival (BCSS). Compared with non-OBC, OBC presented significantly more adverse clinicopathological prognostic features. More patients with OBC underwent breast-conserving treatment (BCT) and less had axillary lymphadenectomy (ALD). Outcomes were more favorable in OBC cases compared with non-OBC cases (p = .002 for OS, p = .002 for BCSS). Triple-negative (TNBC) and HER2-enriched were the subtypes with the worst prognosis in OBC (p < .05). Prognosis was better for triple-negative OBC compared with the same subtype of non-OBC. N-stage was not a strong prognostic indicator of OBC (p > .05 for OS). Cases who underwent systemic chemotherapy alone without surgery had the worst prognosis among OBC patients. For locoregional therapy, mastectomy and radiotherapy could confer survival advantage; standard axillary lymph node dissection (ALND) and positive lymph node dissection (PLND) contributed notably to OS in OBC patients. Both OS and BCSS were better in OBC cases compared with non-OBC. Systemic chemotherapy alone without surgery is not appropriate for OBC treatment, and mastectomy plus standard axillary surgery is recommended. Patients with hormone receptor-positive and low burden of axillary lymph node metastasis may be spared from radiotherapy after undergoing standard axillary lymphadenectomy.

Surgical treatment trends and identification of primary breast tumors after surgery in occult breast cancer: a study based on the Japanese National Clinical Database-Breast Cancer Registry

BACKGROUND

Occult breast cancer (OBC) is classified as carcinoma of an unknown primary site, and the adequate therapy for OBC remains controversial. This retrospective study aimed to reveal the transition in breast cancer therapy and the frequency of primary breast tumors after resection in clinical OBC (cT0N+) patients using the Japanese Breast Cancer Registry database.

METHODS

We enrolled OBC patients with cT0N+ from the registry between 2010 and 2018. On the basis of the period of diagnosis, OBC patients were divided into the following two groups: 2010-2014 and 2015-2018. We described the transition in treatments and tumor characteristics. After breast resection, the frequency of pathological identification of primary tumors and tumor sizes was assessed.

RESULTS

Of the 687,468 patients registered, we identified 148 cT0N+ patients with a median age of 61 years. Of these patients, 64.2% (n = 95) received breast surgery (2010-2014: 79.1%, 2015-2018: 50.0%). Axillary lymph node dissection was performed in 92.6% (n = 137, 2010-2014: 91.6%, 2015-2018: 93.4%). The breast tumor size in the resected breast was 0-7.0 cm (median: 0 cm, 2010-2014: 0-7.0 cm [median: 0 cm], 2015-2018: 0-6.2 cm [median: 0 cm]). The pathological identification rate of the primary tumor was 41.1% (n = 39, 2010-2014: 40.4%, 2015-2018: 42.1%).

CONCLUSIONS

Breast surgery for cT0N+ decreased between 2010 and 2018. Despite the high identification rate of primary tumors, most tumors were small, and there was no significant change in the identification rate or invasive diameter of the identified tumors after 2010.

Treatment for occult breast cancer: A propensity score analysis of the National Cancer Database

BACKGROUND

Controversy exists regarding optimal treatment of occult breast cancer (OBC). Treatment options include mastectomy alone (MAST), radiation alone (XRT), or mastectomy with radiation (MXRT).

METHODS

We queried the National Cancer Database from 2004 to 2014 for patients with OBC who underwent MAST, XRT, or MXRT. We utilized propensity score matching to perform three head-to-head comparisons. Kaplan-Meier analysis was performed to compare overall survival (OS).

RESULTS

A total of 190 patients received XRT, 237 received MAST, and 244 received MXRT. In the MXRT vs. XRT comparison, 5-year OS was 78.2% and 82.8%, respectively. In the MXRT vs. MAST comparison, 5-year OS was 81.5% and 86.7%, respectively. In the MAST vs. XRT comparison, 5-year OS was 83.2% and 82.5%, respectively. There was no difference in OS for all paired comparisons.

CONCLUSIONS

There were no OS differences in patients undergoing MAST, XRT, or MXRT, suggesting that breast conservation can be considered in patients with OBC.

Outcome of breast-conserving treatment for axillary lymph node metastasis from occult breast cancer with negative breast MRI

Purpose

We conducted this study to investigate the prognosis and failure pattern after breast-conserving treatment (BCT) in patients with occult breast cancer (OBC) with negative breast magnetic resonance imaging (MRI) (MRI-OBC).

Materials and methods

Survival rates and failure patterns in 66 patients who received axillary lymph node dissection (ALND) and BCT for MRI-OBC between 2001 and 2013 at seven hospitals were analyzed. OBC was defined as adenocarcinoma in the axillary lymph node (ALN) +/− supraclavicular (SCN) or internal mammary lymph node (IMN) with a negative breast MRI.

Results

Fifty-four patients had only ALN metastasis (ALN only), and 12 patients had ALN metastasis along with SCN or IMN metastasis (ALN + SCN/IMN). Median follow-up was 82 months. The 5-year overall, disease-free, and breast cancer-free survival rates were 93.4%, 92.1%, and 96.8%, respectively. Nine patients experienced recurrence: breast (n = 4), regional lymph nodes (RLN, n = 1), distant metastases (DM, n = 2), breast/RLN (n = 1), and breast/RLN/DM (n = 1). Five-year disease-free survival was significantly higher in ALN only patients compared to ALN + SCN/IMN patients (96.1% vs. 75.0%; p = 0.02).

Conclusions

Patients with MRI-OBC were successfully treated with BCT. There was a small risk of ipsilateral breast cancer recurrence. Failure patterns depended on the extent of initial disease.

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Occult breast cancer (OBC) presenting with axillary metastases is a rare disease.

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This study reports on the outcome of OBC with negative breast MRI (MRI-OBC).

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Patients with MRI-OBC were successfully treated with breast-conserving treatment.

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Very few breast recurrences occurred when whole breast radiotherapy was used.

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Failure patterns of MRI-OBC depended on the initial extent of nodal involvement.

Evaluation of the benefit of post-mastectomy radiotherapy in patients with early-stage breast cancer: A propensity score matching study

The present study aimed to evaluate the significance of post-mastectomy radiotherapy (PMRT) in patients with early stage (T1-2) breast cancer. The Surveillance, Epidemiology, and End Results database was searched, and data on female patients with early stage (T1-2) breast cancer with 1–3 positive axillary lymph nodes (LNs) were extracted. Patients were subdivided into two groups: Those who had received PMRT and those who had not (no PMRT). Data from the two groups were analyzed in order to identify associations between PMRT status, breast cancer-specific survival (BCSS) probability and overall survival (OS) probability using multivariate Cox proportional hazards regression and propensity score matching models. A total of 7,316 patients were included in the analysis. Prior to propensity score matching, outcome probabilities were increased in the PMRT group, compared with the no PMRT group (BCSS probabilities: 92.0 vs. 90.1%, respectively, P=0.015; OS probabilities: 89.8 vs. 86.0%, respectively, P<0.001). In multivariate analyses, tumor location was not identified as being a risk factor for BCSS (hazard ratio, 0.917; 95% confidence interval, 0.772–1.090; P=0.326). Following propensity score matching, differences between the two treatment groups (PMRT and no PMRT) in terms of their BCSS scores remained significant (93.7 vs. 90.1%, respectively; P=0.007). Compared with the no PMRT group, the OS probabilities of the PMRT group were increased (89.4 vs. 86.0%; P=0.025). In conclusion, the present results indicated that PMRT may benefit the prognosis of patients with breast cancer with early stage disease (T1-2), and those with one to three positive axillary LNs.

Clinicopathological characteristics and treatment outcomes of occult breast cancer: a SEER population-based study

Background

Occult breast cancer (OBC) is a rare type of breast cancer that has not been well studied. The clinicopathological characteristics and treatment recommendations for OBC are based on a limited number of retrospective studies and thus remain controversial.

Patients and methods

We identified 479 OBC patients and 115,739 non-OBC patients from 2004 to 2014 in and the Surveillance, Epidemiology, and End Results (SEER) database. The clinicopathological characteristics and survival outcomes were compared between OBC and non-OBC patients. We used the propensity score 1:1 matching analysis to evaluate OBC vs non-OBC comparison using balanced groups with respect to the observed covariates. We further divided the OBC population into four groups based on different treatment strategies. Univariable and multivariable analyses were used to calculate and compare the four treatment outcomes within the OBC population.

Results

OBC patients were older, exhibited a more advanced stage, a higher rate of negative estrogen receptor and progesterone receptor status, a higher rate of HER2-positive status, and a higher rate of ≥10 positive lymph nodes, and were less likely to undergo surgical treatment than non-OBC patients. After adjustments for clinicopathological factors, the OBC patients exhibited a significantly better survival than the non-OBC patients (P<0.001). This result was confirmed in a 1:1 matched case–control analysis. Within the four OBC treatment groups, we observed no difference in survival among the mastectomy group, the breast-conserving surgery (BCS) group, and the axillary lymph node dissection (ALND)-only group. The multivariable analysis revealed that the sentinel lymph node dissection-only group had the worst prognosis (P<0.001). Conclusion: OBC has unique clinicopathological characteristics and a favorable prognosis compared with non-OBC. BCS plus ALND and radiotherapy showed a survival benefit that was similar to that of mastectomy for OBC patients.

A retrospective study of optimal surgical management for occult breast carcinoma: Mastectomy or quadrantectomy?

The diagnosis and treatment for occult breast carcinoma (OBC) remain controversial because of no detectable primary lesions. We aimed to analyze optimal surgical management for OBC.A total of 26 female patients diagnosed with OBC, which were based on available criteria, were collected at a single clinic center from January 2005 to May 2016. We classified all patients into 4 groups: group A1, mastectomy with axillary lymph node dissection (ALND) + radiotherapy (RT); group A2, mastectomy with ALND; group B1, quadrantectomy with ALND + RT; group B2, quadrantectomy with ALND. Patient characteristics, disease-free survival, and overall survival were compared between groups.There were 14 cases in group A1, 5 cases in group A2, 4 cases in group B1, and 3 cases in group B2. Baseline characteristics were similar among groups. Compared with OBC patients treated with quadrantectomy, the disease-free survival (DFS) and overall survival (OS) rate of those treated with mastectomy had significantly improved (A1 vs. B1, DFS: hazard ratio [HR] 0.018, 95% confidence interval [CI] 0.001-0.241, P = .002; OS: HR 0.002, 95% CI 0.000-0.102, P = .002). Patients treated with radiotherapy had higher local recurrence and OS rate compared with patients treated with no radiotherapy on univariate survival analysis (A1 vs. A2, DFS: HR 0.018, 95% CI 0.001-0.240, P = .002; OS: HR 0.005, 95% CI 0.000-0.170, P = .003).The diagnosis of OBC will need continuous improvement with advances of diagnostic breast imaging. Modified radical mastectomy + RT is still a safe and effective choice.