Association between unilateral or bilateral mastectomy and breast cancer death in patients with unilateral ductal carcinoma

Current Status of Contralateral Prophylactic Mastectomy: Investigating Structural Racial Disparity

BACKGROUND

Contralateral prophylactic mastectomy (CPM) remains a personal decision, influenced by psychosocial factors, including cosmesis and peace of mind. Although use of CPM is disproportionately low among Black patients, the degree to which these disparities are driven by patient- vs hospital-level factors remains unknown.

STUDY DESIGN

Patients undergoing mastectomy for nonmetastatic ductal or lobular breast cancer were tabulated using the National Cancer Database from 2004 to 2020. The primary endpoint was receipt of CPM. Multivariable logistic regression models were constructed with interaction terms between Black-serving hospital (BSH) status and patient race to evaluate associations with CPM. Cox proportional hazard models were used to evaluate long-term survival.

RESULTS

Of 597,845 women studied, 70,911 (11.9%) were Black. After multivariable adjustment, Black race (adjusted odds ratio 0.65, 95% CI 0.64 to 0.67) and treatment at BSH (adjusted odds ratio 0.84, 95% CI 0.83 to 0.85) were independently linked to lower odds of CPM. Although predicted probability of CPM was universally lower at higher BSH, Black patients faced a steeper reduction compared with White patients. Receipt of CPM was linked to improved survival (hazard ratio [HR] 0.84, 95% CI 0.83 to 0.86), whereas Black race was associated with a greater HR of 10-year mortality (HR 1.14, 95% CI 1.12 to 1.17).

CONCLUSIONS

Hospitals serving a greater proportion of Black patients are less likely to use CPM, suggestive of disparities in access to CPM at the institutional level. Further research and education are needed to characterize surgeon-specific and institutional practices in patient counseling and shared decision-making that shape disparities in access to CPM.

Construction and Validation of a Nomogram Predicting the Overall Survival Benefit of Unilateral Breast Cancer Patients Undergoing Contralateral Prophylactic Mastectomy

BACKGROUND

Currently, research on the prognostic factors of unilateral breast cancer (UBC) patients receiving contralateral prophylactic mastectomy (CPM) is limited. This study aimed to construct a new nomogram to predict these patients' overall survival (OS).

METHODS

In this retrospective study, 88,477 patients who underwent CPM or unilateral mastectomy (UM) were selected from the Surveillance, Epidemiology, and End Results database. Kaplan-Meier curves and Cox regression analyses were used to determine the difference in the impact of the 2 surgical methods on the prognosis. Multivariate Cox analysis was used to determine the best prognostic variable and construct a nomogram. The concordance index (C-index), receiver operating characteristic (ROC) curve, calibration curve, decision curve analysis (DCA), net reclassification improvement (NRI), and integrated discrimination improvement (IDI) were used to evaluate the discrimination capability and clinical effectiveness of the nomogram.

RESULTS

The prognosis of patients receiving CPM and UM was significantly different. The DCA curves indicated that the nomogram could provide more excellent clinical net benefits for these patients. The NRI and IDI of the nomogram demonstrated that its performance was better than that of the classical tumor-node-metastasis (TNM) staging system.

CONCLUSION

This study developed and validated a practical nomogram to predict the OS of UBC patients undergoing CPM, which provided a beneficial tool for clinical decision-making management.

Canada follows the US in the rise of bilateral mastectomies for unilateral breast cancer: a 23-year population cohort study

INTRODUCTION

The use of contralateral prophylactic mastectomy (CPM) continues to grow despite the absence of evidence supporting a survival benefit. This study's objectives were to (1) describe the trends in the rates of unilateral and bilateral mastectomy (BM) in women diagnosed with unilateral breast cancer (UBC) in Ontario, Canada from 1991 to 2013, and (2) identify factors associated with BM to treat UBC.

METHODS

This retrospective cohort analysis included all women aged 18 and older diagnosed with UBC between January 1991 and December 2013. Health administrative data from the Institute for Clinical Evaluative Sciences, the Ontario Cancer Registry, and the Discharge Abstract Database were used to identify all breast cancer and mastectomy cases. Age-adjusted mastectomy rates were plotted over time. Univariable and multivariable analyses included clinically significant covariates.

RESULTS

From 1991 to 2013 there were 172,165 cases of UBC and 64,886 mastectomies (37.7%) performed in Ontario. 13.6% of the mastectomies were bilateral. BM rates increased over sixfold (from 4 to 25%) across all age groups under age 70 over a 23-year period. On multivariable analysis, younger age, higher income, rural community, earlier breast cancer stage, lobular histology, availability of reconstruction and teaching hospitals were associated with increased odds of BM.

CONCLUSIONS

This is the largest population study of breast cancer patients in Canada and shows an increasing rate of BM for UBC. The results are similar to those already described in the US and highlight the importance of continued efforts to promote efficient communication and evidence-based decision-making prior to breast surgery.

Second primary breast cancer after unilateral mastectomy alone or with contralateral prophylactic mastectomy

Background

An increasing number of patients undergo contralateral prophylactic mastectomy (CPM) for unilateral breast cancer. However, the benefit of CPM has not been quantified in the setting of contemporary breast cancer therapy.

Methods

We performed an analysis of 180 068 patients in the Surveillance, Epidemiology, and End Results (SEER) database, diagnosed with unilateral ductal breast carcinoma between 1998 and 2013 and treated with unilateral mastectomy (UM) or CPM. UM was performed in 146 213 patients (81.2%); CPM was performed in 33 855 patients (19.8%). Primary outcome of interest was cumulative incidence of a second primary breast cancer in the ipsilateral or contralateral breast greater than 3 months after initial diagnosis. Cumulative incidence analysis was based on a Cox proportional model to generate curves of second primary breast cancer in any breast, ipsilateral breast only, or contralateral breast only.

Results

Patients who underwent CPM had a significantly reduced incidence of second primary breast cancer 10 and 15 years after surgery (CPM 0.93% [0.73%, 1.12%] vs UM 4.44% [4.28%, 4.60%]). Patients who underwent CPM had significantly lower adjusted hazard of second primary breast cancer when compared with UM (HR 0.38 vs 1.0, P < .0001).

Conclusions

CPM offers some protection from a second primary breast cancer, attributable to a reduced incidence in the contralateral breast. These findings provide additional information to providers and patients as they make decisions regarding surgical management. They should also be interpreted in the context of the absolute incidence of second primary breast cancer after UM and previous literature demonstrating no survival benefit.

Magnitude of reduction in risk of second contralateral breast cancer with bilateral mastectomy in patients with breast cancer: Data from California, 1998 through 2015

BACKGROUND

Increasingly, patients with breast cancer undergo bilateral mastectomy (BLM). To the authors' knowledge, the magnitude of benefit is unknown.

METHODS

The authors used data from the Surveillance, Epidemiology, and End Results (SEER) program regarding all women diagnosed with American Joint Committee on Cancer stage 0 to stage III unilateral breast cancer in California from 1998 through 2015 and treated with BLM versus breast-conserving therapy including surgery and radiotherapy (BCT) or unilateral mastectomy (ULM). The authors measured relative risks of second contralateral breast cancer (CBC) and breast cancer death using Fine and Gray multivariable regression modeling adjusted for the competing risk of death and death from another cause, respectively, and potential confounding factors. Absolute excess risk of CBC was measured as the observed minus expected number of breast cancers in the general population divided by 10,000 person-years at risk.

RESULTS

Among 245,418 patients with a median follow-up of 6.7 years, 7784 patients (3.2%) developed CBC. Relative risks were lower after BLM (hazard ratio [HR], 0.10; 95% CI, 0.07-0.14) and higher after ULM (HR, 1.07; 95% CI, 1.02-1.13) versus BCT. Absolute excess risks were higher after BCT and ULM (5.0 and 13.6 more cases, respectively) compared with BLM (28.6 fewer cases). BLM reduced risk more among older women (38.0 fewer cases for women aged ≥50 years vs 17.9 fewer cases among women aged <50 years) but provided similar risk reduction across categories of tumor grade and tumor hormone receptor status. Compared with BCT, the risk of breast cancer death was equivalent after BLM (HR, 1.03; 95% CI, 0.96-1.11) and higher after ULM (HR, 1.21; 95% CI, 1.17-1.25).

CONCLUSIONS

BLM may reduce second breast cancer risk by 34 to 43 cases per 10,000 person-years compared with other surgical procedures, but is not associated with a lower risk of death. Second breast cancers are rare, and their reduction should be weighed against the harms associated with BLM.

No survival improvement of contralateral prophylactic mastectomy among women with invasive lobular carcinoma

BACKGROUND AND OBJECTIVE

The prognosis of contralateral prophylactic mastectomy (CPM) in women with breast cancer has been widely reported. Here, we evaluated the survival outcome among patients with invasive lobular carcinoma (ILC) to determine the potential benefit of CPM.

METHODS

We used the Surveillance, Epidemiology, and End Results database to identify patients with ILC diagnosed between 1998 and 2010. Survival differences were compared between unilateral mastectomy and CPM. Propensity score matching and risk-stratified subgroup analyses were conducted to reduce selection bias.

RESULTS

Among 10 226 patients with ILC, 21.8% women underwent CPM, and the rate of CPM nearly tripled over a 13-year period. Kaplan-Meier curves and hazard ratio (HR) of non-breast cancer-specific survival (non-BCSS) in multivariate analysis reflected a pre-existing selection bias in the present cohort. A Cox proportional hazard model confirmed that patients who received CPM had significantly better BCSS and overall survival (OS) in the prematching population (BCSS: HR = 0.90; OS: HR = 0.93). However, the survival improvement could not be achieved in the postmatching cohort. None of the defined subgroups had OS benefits when CPM was performed.

CONCLUSIONS

CPM offers no survival advantage to patients with ILC. The role of CPM among ILC women should be further investigated by incorporating more objective factors.