Prediction of contralateral breast cancer: external validation of risk calculators in 20 international cohorts

Society of Surgical Oncology Breast Disease Site Working Group Statement on Contralateral Mastectomy: Indications, Outcomes, and Risks

Rates of contralateral mastectomy (CM) among patients with unilateral breast cancer have been increasing in the United States. In this Society of Surgical Oncology position statement, we review the literature addressing the indications, risks, and benefits of CM since the society's 2017 statement. We held a virtual meeting to outline key topics and then conducted a literature search using PubMed to identify relevant articles. We reviewed the articles and made recommendations based on group consensus. Patients consider CM for many reasons, including concerns regarding the risk of contralateral breast cancer (CBC), desire for improved cosmesis and symmetry, and preferences to avoid ongoing screening, whereas surgeons primarily consider CBC risk when making a recommendation for CM. For patients with a high risk of CBC, CM reduces the risk of new breast cancer, however it is not known to convey an overall survival benefit. Studies evaluating patient satisfaction with CM and reconstruction have yielded mixed results. Imaging with mammography within 12 months before CM is recommended, but routine preoperative breast magnetic resonance imaging is not; there is also no evidence to support routine postmastectomy imaging surveillance. Because the likelihood of identifying an occult malignancy during CM is low, routine sentinel lymph node surgery is not recommended. Data on the rates of postoperative complications are conflicting, and such complications may not be directly related to CM. Adjuvant therapy delays due to complications have not been reported. Surgeons can reduce CM rates by encouraging shared decision making and informed discussions incorporating patient preferences.

Contralateral prophylactic mastectomy for unilateral breast cancer in Chinese female population: a retrospective cohort study

Background

Due to differences in socioeconomic and cultural backgrounds, the characteristics and prognosis of Asian female patients choosing contralateral prophylactic mastectomy (CPM) are likely to be different from Western patients. To fill the research gap of CPM in Asian populations, this study aims to explore the application trend, survival benefits, decision-making factors, and satisfaction of CPM based on the Chinese patients undergoing CPM.

Methods

The 0-III stage unilateral breast cancer (UBC) patients who received breast surgery in the Chinese PLA General Hospital from 2005 to 2017 were selected. The surgical procedures included simple mastectomy (SM), nipple-sparing mastectomy (NSM), breast conserving surgery (BCS), and CPM. Cox proportional regression analyses and Kaplan-Meier (KM) curve were performed to compare the overall survival (OS) and disease-free survival (DFS) rates between CPM group and unilateral mastectomy (UM) group. Proportional propensity score matching (PSM) with a 1:1 ratio was used to match the two groups and secondary survival analysis was performed. Logistic regression models were used to test predictive factors related to patients' CPM surgical decision-making.

Results

Four thousand two hundred and seventy-six patients were included in the study, with 73 patients receiving CPM, 3,567 receiving SM, 151 receiving NSM, and 485 receiving BCS. CPM surgery was first used in 2007, with a peak application rate of 3.02% in 2016. Three thousand seven hundred and ninety-one patients were included in the survival analysis, with a median follow-up time of 66.60 months. Compared to UM patients, neither the KM survival curve nor Cox regression hazard analyses of CPM showed better OS (P=0.963; P=0.834). After PSM, CPM also did not exhibit significant survival benefits in OS (P=0.335) and DFS (P=0.409). The logistic regression analyses showed that NSM surgery and lower tumor-node-metastasis (TNM) stage were independent factors to promote the CPM decision-making of patients. The CPM group showed high overall satisfaction (84.9%) and relatively low appearance satisfaction (69.9%).

Conclusions

CPM was practiced for the first time since 2007 in our hospital. CPM does not provide any OS and DFS benefits compared to UM and the appearance satisfaction procedure was relatively low. Therefore, clinicians should fully communicate with patients before surgery and be more cautious in giving CPM recommendations.

Trends in Radiation Dose to the Contralateral Breast During Breast Cancer Radiation Therapy

Over 4 million survivors of breast cancer live in the United States, 35% of whom were treated before 2009. Approximately half of patients with breast cancer receive radiation therapy, which exposes the untreated contralateral breast to radiation and increases the risk of a subsequent contralateral breast cancer (CBC). Radiation oncology has strived to reduce unwanted radiation dose, but it is unknown whether a corresponding decline in actual dose received to the untreated contralateral breast has occurred. The purpose of this study was to evaluate trends in unwanted contralateral breast radiation dose to inform risk assessment of second primary cancer in the contralateral breast for long-term survivors of breast cancer. Individually estimated radiation absorbed doses to the four quadrants and areola central area of the contralateral breast were estimated for 2,132 women treated with radiation therapy for local/regional breast cancers at age <55 years diagnosed between 1985 and 2008. The two inner quadrant doses and two outer quadrant doses were averaged. Trends in dose to each of the three areas of the contralateral breast were evaluated in multivariable models. The population impact of reducing contralateral breast dose on the incidence of radiation-associated CBC was assessed by estimating population attributable risk fraction (PAR) in a multivariable model. The median dose to the inner quadrants of the contralateral breast was 1.70 Gy; to the areola, 1.20 Gy; and to the outer quadrants, 0.72 Gy. Ninety-two percent of patients received ≥1 Gy to the inner quadrants. For each calendar year of diagnosis, dose declined significantly for each location, most rapidly for the inner quadrants (0.04 Gy/year). Declines in dose were similar across subgroups defined by age at diagnosis and body mass index. The PAR for CBC due to radiation exposure >1 Gy for women <40 years of age was 17%. Radiation dose-reduction measures have reduced dose to the contralateral breast during breast radiation therapy. Reducing the dose to the contralateral breast to <1 Gy could prevent an estimated 17% of subsequent radiation-associated CBCs for women treated under 40 years of age. These dose estimates inform CBC surveillance for the growing number of breast cancer survivors who received radiation therapy as young women in recent decades. Continued reductions in dose to the contralateral breast could further reduce the incidence of radiation-associated CBC.

EBCC-13 manifesto: Balancing pros and cons for contralateral prophylactic mastectomy

After a diagnosis of unilateral breast cancer, increasing numbers of patients are requesting contralateral prophylactic mastectomy (CPM), the surgical removal of the healthy breast after diagnosis of unilateral breast cancer. It is important for the community of breast cancer specialists to provide meaningful guidance to women considering CPM. This manifesto discusses the issues and challenges of CPM and provides recommendations to improve oncological, surgical, physical and psychological outcomes for women presenting with unilateral breast cancer: (1) Communicate best available risks in manageable timeframes to prioritise actions; better risk stratification and implementation of risk-assessment tools combining family history, genetic and genomic information, and treatment and prognosis of the first breast cancer are required; (2) Reserve CPM for specific situations; in women not at high risk of contralateral breast cancer (CBC), ipsilateral breast-conserving surgery is the recommended option; (3) Encourage patients at low or intermediate risk of CBC to delay decisions on CPM until treatment for the primary cancer is complete, to focus on treating the existing disease first; (4) Provide patients with personalised information about the risk:benefit balance of CPM in manageable timeframes; (5) Ensure patients have an informed understanding of the competing risks for CBC and that there is a realistic plan for the patient; (6) Ensure patients understand the short- and long-term physical effects of CPM; (7) In patients considering CPM, offer psychological and surgical counselling before surgery; anxiety alone is not an indication for CPM; (8) Eliminate inequality between countries in reimbursement strategies; CPM should be reimbursed if it is considered a reasonable option resulting from multidisciplinary tumour board assessment; (9) Treat breast cancer patients at specialist breast units providing the entire patient-centred pathway.

BRCA-CRisk: A Contralateral Breast Cancer Risk Prediction Model for BRCA Carriers

PURPOSE

The absolute cumulative risk of contralateral breast cancer (CBC) for patients with BRCA1/2 variants is unknown. The purpose of this study was to develop a CBC risk prediction model for assessing CBC risk for BRCA1/2 carriers.

METHODS

The primary cohort of 491 patients with BRCA1/2 variants was derived from a large series of unselected patients with breast cancer. A nomogram was established on the basis of the results of a multivariate Cox regression analysis from this cohort. This model, named BRCA-CRisk, was further validated by an independent cohort of 205 patients with BRCA1/2 variants. Discrimination and calibration of the model were assessed.

RESULTS

In the primary cohort of 491 patients, 66 developed contralateral breast cancer after a median follow-up of 7.0 years. Four variables were significantly associated with risk of CBC and were incorporated in the establishment of the BRCA-CRisk prediction model: younger age at first breast cancer (with continuous variable, P = .002), positive first-degree family history of breast and/or ovarian cancer (hazard ratio [HR], 1.89; 95% CI, 1.16 to 3.08; P = .011), variant located near the 3' region of BRCA (HR, 2.01; 95% CI, 1.23 to 3.30; P = .006), and endocrine therapy (HR, 0.54; 95% CI, 0.33 to 0.88; P = .013). The area under the time-dependent curves for the 5- and 10-year cumulative risks of CBC were 0.775 and 0.702, respectively. The model was well validated in the independent cohort of 205 BRCA1/2 carriers, with area under the curves of 0.750 and 0.691 for 5 and 10 years, respectively.

CONCLUSION

BRCA-CRisk model provides a useful tool for assessing the absolute cumulative risk of CBC for BRCA1/2 carriers and may help carriers and clinicians optimally select risk-reducing strategies on the basis of individual CBC risk.

The Contribution of Germline Pathogenic Variants in Breast Cancer Genes to Contralateral Breast Cancer Risk in BRCA1/BRCA2/PALB2-Negative Women

BACKGROUND

Contralateral breast cancer (CBC) is associated with younger age at first diagnosis, family history and pathogenic germline variants (PGVs) in genes such as BRCA1, BRCA2 and PALB2. However, data regarding genetic factors predisposing to CBC among younger women who are BRCA1/2/PALB2-negative remain limited.

METHODS

In this nested case-control study, participants negative for BRCA1/2/PALB2 PGVs were selected from the WECARE Study. The burden of PGVs in established breast cancer risk genes was compared in 357 cases with CBC and 366 matched controls with unilateral breast cancer (UBC). The samples were sequenced in two phases. Whole exome sequencing was used in Group 1, 162 CBC and 172 UBC (mean age at diagnosis: 42 years). A targeted panel of genes was used in Group 2, 195 CBC and 194 UBC (mean age at diagnosis: 50 years). Comparisons of PGVs burdens between CBC and UBC were made in these groups, and additional stratified sub-analysis was performed within each group according to the age at diagnosis and the time from first breast cancer (BC).

RESULTS

The PGVs burden in Group 1 was significantly higher in CBC than in UBC (p = 0.002, OR = 2.5, 95CI: 1.2-5.6), driven mainly by variants in CHEK2 and ATM. The proportions of PGVs carriers in CBC and UBC in this group were 14.8% and 5.8%, respectively. There was no significant difference in PGVs burden between CBC and UBC in Group 2 (p = 0.4, OR = 1.4, 95CI: 0.7-2.8), with proportions of carriers being 8.7% and 8.2%, respectively. There was a significant association of PGVs in CBC with younger age. Metanalysis combining both groups confirmed the significant association between the burden of PGVs and the risk of CBC (p = 0.006) with the significance driven by the younger cases (Group 1).

CONCLUSION

In younger BRCA1/BRCA2/PALB2-negative women, the aggregated burden of PGVs in breast cancer risk genes was associated with the increased risk of CBC and was inversely proportional to the age at onset.

PredictCBC-2.0: a contralateral breast cancer risk prediction model developed and validated in ~ 200,000 patients

BACKGROUND

Prediction of contralateral breast cancer (CBC) risk is challenging due to moderate performances of the known risk factors. We aimed to improve our previous risk prediction model (PredictCBC) by updated follow-up and including additional risk factors.

METHODS

We included data from 207,510 invasive breast cancer patients participating in 23 studies. In total, 8225 CBC events occurred over a median follow-up of 10.2 years. In addition to the previously included risk factors, PredictCBC-2.0 included CHEK2 c.1100delC, a 313 variant polygenic risk score (PRS-313), body mass index (BMI), and parity. Fine and Gray regression was used to fit the model. Calibration and a time-dependent area under the curve (AUC) at 5 and 10 years were assessed to determine the performance of the models. Decision curve analysis was performed to evaluate the net benefit of PredictCBC-2.0 and previous PredictCBC models.

RESULTS

The discrimination of PredictCBC-2.0 at 10 years was higher than PredictCBC with an AUC of 0.65 (95% prediction intervals (PI) 0.56-0.74) versus 0.63 (95%PI 0.54-0.71). PredictCBC-2.0 was well calibrated with an observed/expected ratio at 10 years of 0.92 (95%PI 0.34-2.54). Decision curve analysis for contralateral preventive mastectomy (CPM) showed the potential clinical utility of PredictCBC-2.0 between thresholds of 4 and 12% 10-year CBC risk for BRCA1/2 mutation carriers and non-carriers.

CONCLUSIONS

Additional genetic information beyond BRCA1/2 germline mutations improved CBC risk prediction and might help tailor clinical decision-making toward CPM or alternative preventive strategies. Identifying patients who benefit from CPM, especially in the general breast cancer population, remains challenging.

CBCRisk-Black: a personalized contralateral breast cancer risk prediction model for black women

PURPOSE

Black breast cancer (BC) survivors have a higher risk of developing contralateral breast cancer (CBC) than Whites. Existing CBC risk prediction tools are developed based on mostly White women. To address this racial disparity, it is crucial to develop tools tailored for Black women to help them inform about their actual risk of CBC.

METHODS

We propose an absolute risk prediction model, CBCRisk-Black, specifically for Black BC patients. It uses data on Black women from two sources: Breast Cancer Surveillance Consortium (BCSC) and Surveillance, Epidemiology, and End Results (SEER). First, a matched lasso logistic regression model for estimating relative risks (RR) is developed. Then, it is combined with relevant hazard rates and attributable risks to obtain absolute risks. Six-fold cross-validation is used to internally validate CBCRisk-Black. We also compare CBCRisk-Black with CBCRisk, an existing CBC risk prediction model.

RESULTS

The RR model uses data from BCSC on 744 Black women (186 cases). CBCRisk-Black has four risk factors (RR compared to baseline): breast density (2.13 for heterogeneous/extremely dense), family history of BC (2.28 for yes), first BC tumor size (2.14 for T3/T4, 1.56 for TIS), and age at first diagnosis of BC (1.41 for < 40). The area under the receiver operating characteristic curve (AUC) for 3- and 5-year predictions are 0.72 and 0.65 for CBCRisk-Black while those are 0.65 and 0.60 for CBCRisk.

CONCLUSION

CBCRisk-Black may serve as a useful tool to clinicians in counseling Black BC patients by providing a more accurate and personalized CBC risk estimate.

Effects of chemotherapy on contralateral breast cancer risk in BRCA1 and BRCA2 mutation carriers: A nationwide cohort study

Aim

BRCA1/2 mutation carriers with primary breast cancer (PBC) are at high risk of contralateral breast cancer (CBC). In a nationwide cohort, we investigated the effects of chemotherapeutic agents given for PBC on CBC risk separately in BRCA1 and BRCA2 mutation carriers.

Patients and methods

BRCA1 or BRCA2 mutation carriers with an invasive PBC diagnosis from 1990 to 2017 were selected from a Dutch cohort. We estimated cumulative CBC incidence using competing risks analysis. Hazard ratios (HR) for the effect of neo-adjuvant or adjuvant chemotherapy and different chemotherapeutic agents on CBC risk were estimated using Cox regression.

Results

We included 1090 BRCA1 and 568 BRCA2 mutation carriers; median follow-up was 8.9 and 8.4 years, respectively. Ten-year cumulative CBC incidence for treatment with and without chemotherapy was 6.7% [95%CI: 5.1–8.6] and 16.7% [95%CI: 10.8–23.7] in BRCA1 and 4.8% [95%CI: 2.7–7.8] and 16.0% [95%CI: 9.3–24.4] in BRCA2 mutation carriers, respectively. Chemotherapy was associated with reduced CBC risk in BRCA1 (multivariable HR: 0.46, 95%CI: 0.29–0.74); a similar trend was observed in BRCA2 mutation carriers (HR: 0.63, 95%CI: 0.29–1.39). In BRCA1, risk reduction was most pronounced in the first 5 years (HR: 0.32, 95%CI: 0.17–0.61). Anthracyclines and the combination of anthracyclines with taxanes were associated with substantial CBC risk reduction in BRCA1 carriers (HR: 0.34, 95%CI: 0.17–0.68 and HR: 0.22, 95%CI: 0.08–0.62, respectively).

Conclusion

Risk-reducing effects of chemotherapy are substantial for at least 5 years and may be used in personalised CBC risk prediction in any case for BRCA1 mutation carriers.

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Contralateral breast cancer (CBC) risk is high in BRCA1/2 mutation carriers.

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Chemotherapy for primary breast cancer results in decreased CBC risk in BRCA1.

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Anthracyclines with/without taxanes show the largest CBC risk reduction in BRCA1.

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For BRCA2 similar trends are observed as in BRCA1 mutation carriers.

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Chemotherapy must be considered in personalised CBC risk models.

The risk of contralateral breast cancer: a SEER-based analysis

BACKGROUND

We sought to estimate the annual risk and 25-year cumulative risk of contralateral breast cancer among women with stage 0-III unilateral breast cancer.

METHODS

We identified 812,851 women with unilateral breast cancer diagnosed between 1990 and 2015 in the SEER database and followed them for contralateral breast cancer for up to 25 years. Women with a known bilateral mastectomy were excluded. We calculated the annual risk of contralateral breast cancer by age at diagnosis, by time since diagnosis and by current age. We compared risks by ductal carcinoma in situ (DCIS) versus invasive disease, by race and by oestrogen receptor (ER) status of the first cancer.

RESULTS

There were 25,958 cases of contralateral invasive breast cancer diagnosed (3.2% of all patients). The annual risk of contralateral breast cancer over the 25-year follow-up period was 0.37% and the 25-year actuarial risk of contralateral invasive breast cancer was 9.9%. The annual risk varied to a small degree by age of diagnosis, by time elapsed since diagnosis and by current age. The 25-year actuarial risk was similar for DCIS and invasive breast cancer patients (10.1 versus 9.9%). The 25-year actuarial risk was higher for black women (12.7%) than for white women (9.7%) and was lower for women with ER-positive breast cancer (9.5%) than for women with ER-negative breast cancer (11.2%).

CONCLUSIONS

Women with unilateral breast cancer experience an annual risk of contralateral breast cancer ~0.4% per year, which persists over the 25-year follow-up period.

Outcomes Following Negative Screening MRI Results in Korean Women with a Personal History of Breast Cancer: Implications for the Next MRI Interval

Background There are limited data on outcomes following screening breast MRI in women with a personal history of breast cancer (PHBC). Purpose To investigate outcomes and factors associated with subsequent cancers following a negative screening MRI study in women with a PHBC. Materials and Methods Consecutive women with a PHBC and a negative prevalence screening breast MRI result between August 2014 and December 2016 were retrospectively identified. Inclusion criteria were prevalence screening MRI performed as part of routine surveillance protocol (1-3 years after treatment) and follow-up data for at least 12 months. The incidence and characteristics of subsequent cancers were reviewed. Logistic regression analysis was used to investigate associations between clinical-pathologic characteristics and subsequent cancers. Performance metrics were compared among screening MRI, mammography, and US. Results A total of 993 women (mean age ± standard deviation, 53 years ± 10) were evaluated. Ten second in-breast cancers (ie, ipsilateral or contralateral) occurred at a median interval of 31.8 months (range, 13.3-44.8 months) after MRI, of which eight (80%) were ductal carcinoma in situ (DCIS) or node-negative T1 cancers. Only one node-negative T1mi (tumor ≤1 mm) second in-breast cancer visible on a mammogram was detected within 24 months of MRI. Of second in-breast cancers, 40% (four of 10) were detected only at subsequent screening MRI, which was performed a median of 30.5 months after negative prevalence screening MRI. Ten local-regional recurrences occurred at a median interval of 16.9 months (range, 6-35 months). Previous treatment for DCIS was associated with second in-breast cancers (odds ratio, 3.73; 95% CI: 1.04, 13.38; P = .04). In 1048 women who underwent prevalence screening MRI (including all Breast Imaging Reporting and Data System categories), MRI showed a lower abnormal interpretation rate and higher specificity than mammography or US (P < .001 for all). Conclusion After a negative screening MRI result, 90% of subsequent cancers were detected at intervals longer than 24 months and there was a low second in-breast cancer rate (1%). © RSNA, 2021 Supplemental material is available for this article. See also the editorial by Chang in this issue.

Breast adipocyte size associates with ipsilateral invasive breast cancer risk after ductal carcinoma in situ

Although ductal carcinoma in situ (DCIS) is a non-obligate precursor to ipsilateral invasive breast cancer (iIBC), most DCIS lesions remain indolent. Hence, overdiagnosis and overtreatment of DCIS is a major concern. There is an urgent need for prognostic markers that can distinguish harmless from potentially hazardous DCIS. We hypothesised that features of the breast adipose tissue may be associated with risk of subsequent iIBC. We performed a case-control study nested in a population-based DCIS cohort, consisting of 2658 women diagnosed with primary DCIS between 1989 and 2005, uniformly treated with breast conserving surgery (BCS) alone. We assessed breast adipose features with digital pathology (HALO®, Indica Labs) and related these to iIBC risk in 108 women that developed subsequent iIBC (cases) and 168 women who did not (controls) by conditional logistic regression, accounting for clinicopathological and immunohistochemistry variables. Large breast adipocyte size was significantly associated with iIBC risk (odds ratio (OR) 2.75, 95% confidence interval (95% CI) = 1.25-6.05). High cyclooxygenase (COX)-2 protein expression in the DCIS cells was also associated with subsequent iIBC (OR 3.70 (95% CI = 1.59-8.64). DCIS with both high COX-2 expression and large breast adipocytes was associated with a 12-fold higher risk (OR 12.0, 95% CI = 3.10-46.3, P < 0.001) for subsequent iIBC compared with women with smaller adipocyte size and low COX-2 expression. Large breast adipocytes combined with high COX-2 expression in DCIS is associated with a high risk of subsequent iIBC. Besides COX-2, adipocyte size has the potential to improve clinical management in patients diagnosed with primary DCIS.

Bilateral Mastectomy in Women With Unilateral Breast Cancer: A Review

Importance

Rates of bilateral mastectomy continue to increase in average-risk women with unilateral in situ and invasive breast cancer. Contralateral prophylactic mastectomy rates increased from 5% to 12% of all operations for breast cancer in the US from 2004 to 2012. Among women having mastectomy, rates of contralateral prophylactic mastectomy have increased from less than 2% in 1998 to 30% in 2012.

Observations

The increased use of breast magnetic resonance imaging and genetic testing has marginally increased the number of candidates for bilateral mastectomy. Most bilateral mastectomies are performed on women who are at no special risk for contralateral cancer. The true risk of contralateral breast cancer is not associated with the decision for contralateral prophylactic mastectomy; rather, the clinical factors associated with the probability of distant recurrence are associated with bilateral mastectomy. Several changes in society and health care delivery appear to act concurrently and synergistically. First, the anxiety engendered by a fear of cancer recurrence is focused on the contralateral cancer because this is most easily conceptualized and provides a ready target that can be acted upon. Second, the modern woman with breast cancer is supported by the surgeon and the social community of breast cancer survivors. Surgeons want to respect patient autonomy, despite guidelines discouraging bilateral mastectomy, and most women have their expenses covered by a third-party payer. Satisfaction with the results is high, but the association with improved psychosocial well-being remains to be fully understood.

Conclusions and Relevance

Reducing the use of medically unnecessary contralateral prophylactic mastectomy in women with nonhereditary, unilateral breast cancer requires a social change that addresses patient-, physician-, cultural-, and systems-level enabling factors. Such a transformation begins with educating clinicians and patients. The concerns of women who want preventive contralateral mastectomy must be explored, and women need to be informed of the anticipated benefits (or lack thereof) and risks. Areas requiring further study are considered.

Contralateral prophylactic mastectomy: A narrative review of the evidence and acceptability

The uptake of contralateral prophylactic mastectomy (CPM) has increased steadily over the last twenty years in women of all age groups and breast cancer stages. Since contralateral breast cancer is relatively rare and the breast cancer guidelines only recommend CPM in a small subset of patients with breast cancer, the drivers of this trend are unknown. This review aims to evaluate the evidence for and acceptability of CPM, data on patient rationales for choosing CPM, and some of the factors that might impact patient preferences. Based on the evidence, future recommendations will be provided. First, data on contralateral breast cancer risk and CPM rates and trends are addressed. After that, the evidence is structured around four main patient rationales for CPM formulated as questions that patients might ask their surgeon: Will CPM reduce mortality risk? Will CPM reduce the risk of contralateral breast cancer? Can I avoid future screening with CPM? Will I have better breast symmetry after CPM? Also, three different guidelines regarding CPM will be reviewed. Studies indicate a large gap between patient preferences for radical risk reduction with CPM and the current approaches recommended by important guidelines. We suggest a strategy including shared decision-making to enhance surgeons’ communication with patients about contralateral breast cancer and treatment options, to empower patients in order to optimize the use of CPM incorporating accurate risk assessment and individual patient preferences.

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Contralateral prophylactic mastectomy rates have increased over the last 20 years.

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Patients may want CPM to reduce risk of contralateral breast cancer and mortality.

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Patients do not always have the tools available to make a well-informed decision.

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Patient and surgeon’s shared decision-making could optimize the use of CPM.

Clinical characteristics and the associated risk factors of the development of bilateral breast cancers: A case-control study

Background

The clinical impacts of bilateralism on prognosis and clinical decision-making remain contradictory particularly in areas with low incidence and delayed diagnosis of primary breast cancer. Identification of women at risk of bilateral breast cancer is required to improve patient management and to design the appropriate surveillance.

Methods

A total of 1083 women were enrolled and analyzed for the presence of synchronous and metachronous bilateral breast cancer as cases and unilateral breast cancer as controls during the median follow-up of 4.8 years.

Results

The incidence of bilateral breast cancer was 7.5% (81 of 1083). In comparison with unilateral breast cancers, bilateral cases were significantly diagnosed in younger women (P = 0.037, mean age was 35.6 years) who had a larger tumor size (P = 0.012, mean tumor size was 8 cm in diameter). Histological type of lobular cancer was identified as one of the risk factors for the development of contralateral breast cancer (OR 5.564, 95% CI: 3.219-9.620) and synchronous bilateral breast cancer (OR 2.561, 95% CI: 1.182-5.550). Bilateral breast cancer had significantly shorter progression-free survival (Mean survival was 26.6 vs 52.5 months for bilateral and unilateral breast cancers, respectively; P = 0.001) and shorter time to develop distant metastasis (Mean survival was 41.7 vs 104 months for bilateral and unilateral breast cancers, respectively; P = 0.001).

Conclusion

Patients with first primary breast tumors with lobular histological type and advanced stages were observed to have higher risks for the development of contralateral breast cancers.