Age-Related Incidence and Peak Occurrence of Contralateral Breast Cancer

Importance

Young patients with breast cancer have higher risk for developing contralateral breast cancer (CBC) and have epidemiologic characteristics different from those of older patients.

Objective

To examine the incidence and peak occurrence of CBC according to age at primary breast cancer (PBC) surgery.

Design, Setting, and Participants

This cohort study included patients who were diagnosed with and underwent surgery for unilateral nonmetastatic breast cancer at Asan Medical Center, Korea, between January 1, 1999, and December 31, 2013, with follow-up through December 31, 2018. Data were analyzed from December 1, 2021, through April 30, 2023. Patients were divided into 2 groups according to their age at surgery for PBC: younger (≤35 years) vs older (>35 years).

Main Outcomes and Measures

The main outcomes were cumulative incidence and hazard rate of CBC in the entire study population and in subgroups divided by cancer subtype, categorized according to hormone receptor (HR) and ERBB2 status.

Results

A total of 16 251 female patients with stage 0 to III breast cancer were analyzed; all patients were Korean. The mean (SD) age was 48.61 (10.06) years; 1318 patients (8.11%) were in the younger group, and 14 933 (91.89%) were in the older group. Median follow-up was 107 months (IQR, 79-145 months). Compared with the older group, the younger group had significantly higher incidence of CBC (10-year cumulative incidence, 7.1% vs 2.9%; P < .001) and higher risk (hazard ratio, 2.10; 95% CI, 1.62-2.74) of developing CBC. The hazard rate, which indicates risk for developing CBC at a certain time frame, differed according to the subtype of primary cancer. In patients with the HR+/ERBB2- subtype, the risk increased continuously in both age groups. In patients with the triple negative subtype, the risk increased until approximately 10 years and then decreased in both age groups. Meanwhile, in the HR-/ERBB2+ subtype, risk peaked earlier, especially in the younger group (1.7 years since first surgery in the younger group and 4.8 years in the older group).

Conclusions and Relevance

In this cohort study, patients aged 35 years or younger with breast cancer had a higher risk of developing CBC than older patients. Moreover, young patients with the HR-/ERBB2+ subtype tended to have a shorter interval for developing CBC. These findings might be useful in guiding treatment decisions, such as contralateral prophylactic mastectomy.

Survival After Development of Contralateral Breast Cancer in Korean Patients With Breast Cancer

Importance

Contralateral breast cancer (CBC) is the most frequently diagnosed primary cancer in patients with breast cancer. Although many studies have reported survival after the development of CBC, results have been inconsistent.

Objective

To investigate whether the development of CBC is associated with survival among patients with breast cancer.

Design, Setting, and Participants

This cohort study was conducted at the Asan Medical Center, Korea, among patients who were diagnosed with primary unilateral, nonmetastatic, stage 0 to III breast cancer between 1999 and 2013 and followed up through 2018. The median (IQR) follow-up was 107 (75-143) months. Patients were categorized into CBC and no-CBC groups by whether they developed CBC during the follow-up period. Data were analyzed from November 2021 to March 2023.

Exposure

Development of CBC.

Main outcomes and measures

Survival rates of CBC and no-CBC groups were compared using a time-dependent Cox proportional hazard model in the entire study population and in subgroup analyses by interval of CBC development and subtype of the primary breast cancer.

Results

Among 16 251 patients with breast cancer (all Asian, specifically Korean; mean [SD] age, 48.61 [10.06] years), 418 patients developed CBC. There was no significant difference in overall survival between CBC and no-CBC groups (hazard ratio, 1.166; 95% CI, 0.820-1.657). Patients who developed CBC within 1.5 years after the surgery of the primary breast cancer had a higher risk for overall death during the study period (hazard ratio, 2.014; 95% CI, 1.044-3.886), and those who developed CBC after 1.5 years showed no significant difference in survival compared with the no-CBC group. Patients with hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (ERBB2, formerly HER2)-negative breast cancer had a higher risk for overall death in the CBC group (hazard ratio, 1.882; 95% CI, 1.143-3.098) compared with the no-CBC group.

Conclusions and Relevance

This study found that development of CBC in patients with breast cancer was not associated with survival but that early development of CBC after diagnosis of the primary breast cancer or development of CBC in patients with HR-positive/ERBB2-negative breast cancer was associated with survival. These results may provide valuable information for patients seeking advice on opting for contralateral prophylactic mastectomy.

Pregnancy-associated breast cancer: a multicenter study comparing clinicopathological factors, diagnosis and treatment outcomes with non-pregnant patients

PURPOSE

Pregnancy-associated breast cancer (PABC), defined as breast carcinoma diagnosed during pregnancy or in the first post-partum year, is one of the most common gestation-related malignancies with reported differences in tumor characteristics and outcomes. This multicenter study aims to review cases of PABC in Singapore, including their clinicopathological features, treatment, and clinical outcomes compared to non-PABC patients.

METHODS

Demographic, histopathologic and clinical outcomes of 93 PABC patients obtained from our database were compared to 1424 non-PABC patients.

RESULTS

PABC patients presented at a younger age. They had higher tumor and nodal stages, higher tumor grade, were more likely to be hormone receptor negative and had a higher incidence of multicentric and multifocal tumors. Histological examination after definitive surgery showed no significant difference in tumor size and number of positive lymph nodes suggesting similar neoadjuvant treatment effects. Despite this, PABC patients had worse outcomes with poorer overall survival and disease-free survival, OS (P < 0.0001) and DFS (P < 0.0001). Termination of pregnancy did not improve survival.

CONCLUSION

Patients with PABC present at a higher stage with more aggressive disease and have poorer outcomes compared to non-PABC patients. Reducing delay in diagnosis and treatment may help improve survival.

Risk of metachronous contralateral breast cancer in patients with primary invasive lobular breast cancer: Results from a nationwide cohort

Lobular primary breast cancer (PBC) histology has been proposed as a risk factor for contralateral breast cancer (CBC), but results have been inconsistent. We investigated CBC risk and the impact of systemic therapy in lobular versus ductal PBC. Further, CBC characteristics following these histologic subtypes were explored. We selected 74,373 women diagnosed between 2003 and 2010 with stage I-III invasive PBC from the nationwide Netherlands Cancer Registry. We assessed absolute risk of CBC taking into account competing risks among those with lobular (n = 8903), lobular mixed with other types (n = 3512), versus ductal (n = 62,230) histology. Hazard ratios (HR) for CBC were estimated in a cause-specific Cox model, adjusting for age at PBC diagnosis, radiotherapy, chemotherapy and/or endocrine therapy. Multivariable HRs for CBC were 1.18 (95% CI: 1.04-1.33) for lobular and 1.37 (95% CI: 1.16-1.63) for lobular mixed versus ductal PBC. Ten-year cumulative CBC incidences in patients with lobular, lobular mixed versus ductal PBC were 3.2%, 3.6% versus 2.8% when treated with systemic therapy and 6.6%, 7.7% versus 5.6% in patients without systemic therapy, respectively. Metachronous CBCs were diagnosed in a less favourable stage in 19%, 26% and 23% and less favourable differentiation grade in 22%, 33% and 27% than the PBCs of patients with lobular, lobular mixed and ductal PBC, respectively. In conclusion, lobular and lobular mixed PBC histology are associated with modestly increased CBC risk. Personalised CBC risk assessment needs to consider PBC histology, including systemic treatment administration. The impact on prognosis of CBCs with unfavourable characteristics warrants further evaluation.

Use of beta-blockers and risk of contralateral breast cancer

Beta-blockers have shown antineoplastic effects in laboratory studies but epidemiologic evidence in relation to contralateral breast cancer (CBC) is sparse. We investigated postdiagnosis beta-blocker use and risk of CBC in a cohort of 52 723 women with breast cancer by using nationwide Danish health registers and the Danish Breast Cancer Group database. We defined postdiagnosis beta-blocker use as a time-varying covariate starting 1 year after a second prescription was redeemed. Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for CBC associated with beta-blocker use compared to nonuse. We identified 1444 women with CBC of whom 209 women were beta-blocker users. We found an overall HR of 1.08 (95% CI: 0.93-1.27) for beta-blocker use and risk of CBC with no substantial variation according to cumulative amount, intensity or selectivity of beta-blocker use. Hence, our cohort study of women with breast cancer did not sustain a protective effect of beta-blocker use on risk of CBC, irrespective of beta-blocker type.

Mortality After Late Breast Cancer Recurrence in Denmark

PURPOSE

Late breast cancer (BC) recurrence (ie, ≥ 10 years after primary diagnosis) may have a more favorable prognosis than earlier recurrence. We investigated the risk of BC death after late recurrence, identified prognostic factors, and compared survival after early and late recurrence.

METHODS

Using the Danish Breast Cancer Group and other nationwide databases, we identified women with early or late BC recurrence during 2004-2018, who were alive 6 months after recurrence. We followed them until BC death, death from other causes, emigration, 10 years, or December 31, 2018, whichever came first. We calculated mortality rates (MRs) per 1,000 person-years (PY) and cumulative BC mortality, for early versus late recurrence, and by characteristics of the primary tumor and the late recurrence. Using Cox regression, we calculated adjusted hazard ratios (HRs) for BC death, accounting for death from other causes as competing risks.

RESULTS

Among 2,004 patients with late recurrence, 721 died of BC with a median survival time of 10 years (MR = 84.8 per 1,000 PY; 10-year cumulative mortality = 50%). Among 1,528 patients with early recurrence, 1,092 BC deaths occurred with a median survival time of 4 years (MR = 173.9 per 1,000 PY; 10-year cumulative mortality = 72%). We observed a lower hazard of BC-specific death among patients who developed late compared with early recurrence (hazard ratio = 0.72; 95% CI, 0.62 to 0.85). Advanced stage at primary diagnosis, distant metastases, adjuvant treatment for locoregional recurrence, and systemic treatment for distant recurrence were associated with increased mortality after late recurrence. Breast-conserving surgery at primary diagnosis, locoregional recurrence, and surgery for recurrence were associated with lower mortality after late recurrence.

CONCLUSION

Patients with late recurrence had more favorable prognosis than patients with early recurrence. The localization of recurrent disease was the main prognostic factor for BC death.

The Incidence of Breast Cancer Recurrence 10-32 Years after Primary Diagnosis

Background

Extended, more effective breast cancer treatments have increased the prevalence of long-term survivors. We investigated the risk of late breast cancer recurrence (BCR), 10 years or more after primary diagnosis, and associations between patient and tumor characteristics at primary diagnosis and late BCR up to 32 years after primary breast cancer diagnosis.

Methods

Using the Danish Breast Cancer Group clinical database, we identified all women with an incident early breast cancer diagnosed during 1987-2004. We restricted to women who survived 10 years without a recurrence or second cancer (10-year disease-free survivors) and followed them from 10 years after breast cancer diagnosis date until late recurrence, death, emigration, second cancer, or December 31, 2018. We calculated incidence rates per 1000 person-years and cumulative incidences for late BCR, stratifying by patient and tumor characteristics. Using Cox regression, we calculated adjusted hazard ratios for late BCR accounting for competing risks.

Results

Among 36 924 women with breast cancer, 20 315 became 10-year disease-free survivors. Of these, 2595 developed late BCR (incidence rate = 15.53 per 1000 person-years, 95% confidence interval = 14.94 to 16.14; cumulative incidence = 16.6%, 95% confidence interval = 15.8% to 17.5%) from year 10 to 32 after primary diagnosis. Tumor size larger than 20 mm, lymph node–positive disease, and estrogen receptor–positive tumors were associated with increased cumulative incidences and hazards for late BCR.

Conclusions

Recurrences continued to occur up to 32 years after primary diagnosis. Women with high lymph node burden, large tumor size, and estrogen receptor–positive tumors had increased risk of late recurrence. Such patients may warrant extended surveillance, more aggressive treatment, or new therapy approaches.

Individualizing Surveillance Mammography for Older Patients After Treatment for Early-Stage Breast Cancer: Multidisciplinary Expert Panel and International Society of Geriatric Oncology Consensus Statement

Importance

There is currently no guidance on how to approach surveillance mammography for older breast cancer survivors, particularly when life expectancy is limited.

Objective

To develop expert consensus guidelines that facilitate tailored decision-making for routine surveillance mammography for breast cancer survivors 75 years or older.

Evidence

After a literature review of the risk of ipsilateral and contralateral breast cancer events among breast cancer survivors and the harms and benefits associated with mammography, a multidisciplinary expert panel was convened to develop consensus guidelines on surveillance mammography for breast cancer survivors 75 years or older. Using an iterative consensus-based approach, input from clinician focus groups, and critical review by the International Society for Geriatric Oncology, the guidelines were refined and finalized.

Findings

The literature review established a low risk for ipsilateral and contralateral breast cancer events in most older breast cancer survivors and summarized the benefits and harms associated with mammography. Draft mammography guidelines were iteratively evaluated by the expert panel and clinician focus groups, emphasizing a patient's risk for in-breast cancer events, age, life expectancy, and personal preferences. The final consensus guidelines recommend discontinuation of routine mammography for all breast cancer survivors when life expectancy is less than 5 years, including those with a history of high-risk cancers; consideration to discontinue mammography when life expectancy is 5 to 10 years; and continuation of mammography when life expectancy is more than 10 years. Individualized, shared decision-making is encouraged to optimally tailor recommendations after weighing the benefits and harms associated with surveillance mammography and patient preferences. The panel also recommends ongoing clinical breast examinations and diagnostic mammography to evaluate clinical findings and symptoms, with reassurance for patients that these practices will continue.

Conclusions and Relevance

It is anticipated that these expert guidelines will enhance clinical practice by providing a framework for individualized discussions, facilitating shared decision-making regarding surveillance mammography for breast cancer survivors 75 years or older.

What is the most appropriate period to define synchronous cancers?

BACKGROUND

Studies about second primary cancers (SPC) incidence exclude a period following the first cancer diagnosis given the high probability of diagnosing another primary cancer during this phase (synchronous cancers). However, definition of synchronicity period varies widely, from one to six months, without clear epidemiological justification. The objective of this study was to determine the most appropriate synchronicity period.

METHODS

Data from 13 French population-based cancer registries were used to establish a cohort of all patients diagnosed with a first cancer between 1989 and 2010. The incidence rate of subsequent cancer was computed by day within 1 year of follow-up after the first diagnosis. Incidence was modelized by joinpoint regression models with an initial quadratic trend and a second constant part (plateau). The joinpoint was the point from which the plateau began and defining the synchronicity period.

RESULTS

Our cohort included 696,775 patients with a first cancer, of which 12,623 presented a SPC. The median joinpoint for all sites combined was estimated at 120.5 days [112.0-129.0]. Analysis by gender reported a higher difference in 32 days for males (127.8 vs 96.1 days). Noteworthy differences were found depending on patient age and the site of first cancer, with joinpoint ranging from 84.7 (oesophagus cancer) to 250.1 days (bladder cancer).

CONCLUSION

Although some heterogeneity was observed based on the characteristic of the patients, the appropriate synchronicity period appears to be 4 months after the diagnosis of first cancer.

Validation of an Algorithm to Ascertain Late Breast Cancer Recurrence Using Danish Medical Registries

Purpose

About 70% of women with breast cancer survive at least 10 years after diagnosis. We constructed an algorithm to ascertain late breast cancer recurrence—which we define as breast cancer that recurs 10 years or more after primary diagnosis (excluding contralateral breast cancers)—using Danish nationwide medical registries. We used clinical information recorded in medical records as a reference standard.

Methods

Using the Danish Breast Cancer Group clinical database, we ascertained data on 21,134 women who survived recurrence-free 10 years or more after incident stage I–III breast cancer diagnosed in 1987–2004. We used a combination of Danish registries to construct the algorithm—the Danish National Patient Registry for information on diagnostic, therapeutic and procedural codes; and cancer diagnoses from the Danish Pathology Registry, the Danish Cancer Registry and the Contralateral Breast Cancer database. To estimate the positive predictive value (PPV), we selected 105 patients who, according to our algorithm, had late recurrence diagnosed at Aarhus University Hospital. To estimate the sensitivity, specificity and negative predictive value (NPV), we selected 114 patients diagnosed with primary breast cancer at Aalborg University Hospital. We abstracted clinical information on late recurrence for patients with medical record-confirmed late recurrence at Aarhus University Hospital.

Results

Our algorithm had a PPV of late recurrence of 85.7% (95% CI: 77.5–91.3%), a sensitivity of 100.0% (95% CI, 39.8–100.0%), a specificity of 97.3 (95% CI, 92.2–99.4) and a NPV of 100% (95% CI, 96.6–100.0%).

Conclusion

Our algorithm for late recurrence showed a moderate to high PPV and high sensitivity, specificity and negative predictive value. The algorithm could be an important tool for future studies of late breast cancer recurrence.

Bilateral Disease Common Among Slovenian CHEK2-Positive Breast Cancer Patients

BACKGROUND

Currently, data on pathogenic variants in the CHEK2 gene and their impact on cancer risk are lacking. This study aimed to explore the characteristics of breast cancer (BC) patients from families with CHEK2 pathogenic variants in Slovenia.

METHODS

In the years 2014 to 2019, CHEK2 pathogenic variants/likely pathogenic variants (PV/LPVs) were found in probands from 50 different families who underwent genetic counseling and testing using a multigene panel at the authors' institution. Altogether, the study enrolled 75 individuals from 50 CHEK2 families who were carriers of a CHEK2 PV/LPV. The clinical data on 41 BC patients with CHEK2 PV/LPV and other carriers of CHEK2 PV/LPV from Slovenia were collected and analyzed.

RESULTS

Breast cancer was diagnosed in 41 of 75 CHEK2 PV/LPV carriers (40 females, 1 male). The mean age at BC diagnosis was 42.8 years (range, 21-63 years), and 27 (65.8%) of the 41 of patients with BC had a positive family history for BC. Contralateral BC (CBC) was observed in 8 (19.5%) of the 41 patients (mean age, 55.6 years). Of 12 patients with human epidermal growth factor receptor 2 (HER2)-positive tumor type, a c.444+1G > A PV/LPV was detected in 4 patients, c.349A > G in 3 patients, deletion of exons 9-10 in 3 patients, deletion of exon 8 in 1 patient, and c.1427C > T PV/LPV in 1 patient.

CONCLUSION

Bilateral BC was diagnosed in as many as 19.5% of the Slovenian BC patients with CHEK2 PV/LPVs. Breast cancer associated with a germline CHEK2 PV/LPV occurs in younger patients compared with sporadic BC.

Local staging of ipsilateral breast tumor recurrence: mammography, ultrasound, or MRI?

BACKGROUND

Despite increasingly effective curative breast-conserving treatment (BCT) regimens for primary breast cancer, patients remain at risk for an ipsilateral breast tumor recurrence (IBTR). With increasing interest for repeat BCT in selected patients with IBTR, a reliable assessment of the size of IBTR is important for surgical planning.

AIM

The primary aim of this study is to establish the performance in size estimation of XMG, US, and breast MRI in patients with IBTR. The secondary aim is to compare the detection of multifocality and contralateral lesions between XMG and MRI.

PATIENTS AND METHODS

The sizes of IBTR on mammography (XMG), ultrasound (US), and magnetic resonance imaging (MRI) in 159 patients were compared to the sizes at final histopathology. The accuracy of the size estimates was addressed using Pearson's coefficient and Bland-Altman plots. Secondary outcomes were the detection of multifocality and contralateral lesions between XMG and MRI.

RESULTS

Both XMG and US significantly underestimated the tumor size by 3.5 and 4.8 mm, respectively, while MRI provided accurate tumor size estimation with a mean underestimation of 1.1 mm. The sensitivity for the detection of multifocality was significantly higher for MRI compared to XMG (25.5% vs. 5.5%). A contralateral malignancy was found in 4.4% of patients, and in 1.9%, it was detected by MRI only.

CONCLUSION

The addition of breast MRI to XMG and US in the preoperative workup of IBTR allows for more accurate size estimation. MRI provides a higher sensitivity for the detection of multifocality compared to XMG.

Impact of genetic counseling on the uptake of contralateral prophylactic mastectomy among younger women with breast cancer

Background: Preoperative genetic testing affects the surgical decision-making among women with breast cancer. To avoid breast-conserving surgery and to offer the possibility of mastectomy with immediate reconstruction in high-risk patients, genetic testing for pathogenic variants in BRCA1 or BRCA2 and a pedigree-based familial breast cancer risk assessment was offered to younger women with breast cancer in Denmark. We evaluated the impact of the risk stratification through genetic counseling on the uptake of contralateral prophylactic mastectomy (CPM).Material and methods: The prospective cohort study included all women with unilateral breast cancer before the age of 45 who participated in a genetic counseling program during their primary diagnostics in the Central Denmark Region (2013-2018). Each patient was followed from the time of the genetic test result to the end of follow-up to estimate the long-term uptake of CPM as a competing risk-adjusted cumulative incidence. We compared the uptake of CPM between the various genetic risk categories, ages of onset, and family histories in a multivariable Cox proportional hazards regression model, reporting hazard ratios (HR) with two-sided 95% confidence intervals (CIs).Results: 156 females, aged 21-44, learned their genetic test result within a median of 92 days [interquartile range (IQR): 75-114]. The maximal follow-up was 3.8 years (median 1.8; IQR: 0.49-2.5), after which 33% (95% CI: 24-42%) of the patients had undergone CPM. The uptake of CPM was inversely associated with the age of onset (HR 0.92; 95% CI: 0.86-0.98) and significantly higher among BRCA carriers (HR 2.9; 95% CI: 1.3-6.8) and patients from the high risk of breast cancer families (HR 5.6; 95% CI: 1.9-16) compared to the lower genetic risk categories.Conclusion: The risk stratification obtained through genetic counseling had a considerable impact on the surgical decision-making among younger women with breast cancer at long-term follow-up.

Breast cancer risk in BRCA1/2 mutation carriers and noncarriers under prospective intensified surveillance

Comparably little is known about breast cancer (BC) risks in women from families tested negative for BRCA1/2 mutations despite an indicative family history, as opposed to BRCA1/2 mutation carriers. We determined the age-dependent risks of first and contralateral breast cancer (FBC, CBC) both in noncarriers and carriers of BRCA1/2 mutations, who participated in an intensified breast imaging surveillance program. The study was conducted between January 1, 2005, and September 30, 2017, at 12 university centers of the German Consortium for Hereditary Breast and Ovarian Cancer. Two cohorts were prospectively followed up for incident FBC (n = 4,380; 16,398 person-years [PY], median baseline age: 39 years) and CBC (n = 2,993; 10,090 PY, median baseline age: 42 years). Cumulative FBC risk at age 60 was 61.8% (95% CI 52.8-70.9%) for BRCA1 mutation carriers, 43.2% (95% CI 32.1-56.3%) for BRCA2 mutation carriers and 15.7% (95% CI 11.9-20.4%) for noncarriers. FBC risks were significantly higher than in the general population, with incidence rate ratios of 23.9 (95% CI 18.9-29.8) for BRCA1 mutation carriers, 13.5 (95% CI 9.2-19.1) for BRCA2 mutation carriers and 4.9 (95% CI 3.8-6.3) for BRCA1/2 noncarriers. Cumulative CBC risk 10 years after FBC was 25.1% (95% CI 19.6-31.9%) for BRCA1 mutation carriers, 6.6% (95% CI 3.4-12.5%) for BRCA2 mutation carriers and 3.6% (95% CI 2.2-5.7%) for noncarriers. CBC risk in noncarriers was similar to women with unilateral BC from the general population. Further studies are needed to confirm whether less intensified surveillance is justified in women from BRCA1/2 negative families with elevated risk.

Distant metastasis dynamics following subsequent surgeries after primary breast cancer removal

Background

The aim of the research was to separate the distant metastasis (DM) enhancing effect due to breast tumour removal from that due to surgical manoeuvre by itself.

Methods

DM dynamics following surgery for ipsilateral breast tumour recurrence (IBTR), contralateral breast cancer (CBC) and delayed reconstruction (REC), which was performed after the original breast cancer surgical removal, was analysed. A total of 338 patients with IBTR, 239 with CBC and 312 with REC were studied.

Results

The DM dynamics following IBTR, CBC and REC, when assessed with time origin at their surgical treatment, is similar to the analogous pattern following primary tumour removal, with a first major peak at about 18 months and a second lower one at about 5 years from surgery. The time span between primary tumour removal and the second surgery is influential on DM risk levels for IBTR and CBC patients, not for REC patients.

Conclusions

The role of breast tumour removal is different from the role of surgery by itself. Our findings suggest that the major effect of reconstructive surgery is microscopic metastasis acceleration, while breast tumour surgical removal (either primary or IBTR or CBC) involves both tumour homeostasis interruption and microscopic metastasis growth acceleration. The removal of a breast tumour would eliminate its homeostatic restrains on metastatic foci, thus allowing metastasis development, which, in turn, would be supported by the forwarding action of the mechanisms triggered by the surgical wounding.

Breast cancer mortality in synchronous bilateral breast cancer patients

Background

Evidence suggests that patients with synchronous bilateral breast cancer (SBBC), diagnosed within 4 months, have an inferior prognosis compared to unilateral breast cancer (UBC) patients. Using data from nationwide Danish clinical databases, this cohort study investigated whether the inferior prognosis could be explained by SBBC patients having a more aggressive disease, or whether the prognosis could be explained by the fact that they have two simultaneous cancers.

Methods

Patients were diagnosed from 1999–2015. The main outcome was excess mortality, subtracting background population mortality from observed mortality. Differences between SBBC and UBC patients were evaluated by rate ratios (RR) and estimated by Poisson regression.

Results

In total, 1214 SBBC and 59 177 UBC patients were included. SBBC patients had a significantly higher excess mortality than UBC patients after adjustment for age and period (RR = 1.73; 95% CI:1.44–2.08; p < 0.01) and after adjusting for characteristics of the worst tumour as traditionally done (RR = 1.31; 95% CI:1.08–1.57; p = 0.01). However, adjusting for characteristics of both tumours, using a more advanced competing risks model, no difference was observed (RR = 1.01; 95% CI:0.83–1.22; p = 0.93).

Conclusions

Our study does not support that the inferior prognosis in SBBC patients is due to having more aggressive tumours per se, but rather the combined effect of having two simultaneous cancers.

Obesity-Linked Cancers: Current Knowledge, Challenges and Limitations in Mechanistic Studies and Rodent Models

The worldwide prevalence of obesity has doubled during the last 50 years, and according to the World Obesity Federation, one third of the people on Earth will be obese by the year 2025. Obesity is described as a chronic, relapsing and multifactorial disease that causes metabolic, biomechanical, and psychosocial health consequences. Growing evidence suggests that obesity is a risk factor for multiple cancer types and rivals smoking as the leading preventable cause for cancer incidence and mortality. The epidemic of obesity will likely generate a new wave of obesity-related cancers with high aggressiveness and shortened latency. Observational studies have shown that from cancer risk to disease prognosis, an individual with obesity is consistently ranked worse compared to their lean counterpart. Mechanistic studies identified similar sets of abnormalities under obesity that may lead to cancer development, including ectopic fat storage, altered adipokine profiles, hormone fluctuations and meta-inflammation, but could not explain how these common mechanisms produce over 13 different cancer types. A major hurdle in the mechanistic underpinning of obesity-related cancer is the lack of suitable pre-clinical models that spontaneously develop obesity-linked cancers like humans. Current approaches and animal models fall short when discerning the confounders that often coexist in obesity. In this mini-review, we will briefly survey advances in the different obesity-linked cancers and discuss the challenges and limitations in the rodent models employed to study their relationship. We will also provide our perspectives on the future of obesity-linked cancer research.

Risk factors for metachronous contralateral breast cancer: A systematic review and meta-analysis

BACKGROUND

The risk of developing metachronous contralateral breast cancer (CBC) is a recurrent topic at the outpatient clinic. We aimed to provide CBC risk estimates of published patient, pathological, and primary breast cancer (PBC) treatment-related factors.

METHODS

PubMed was searched for publications on factors associated with CBC risk. Meta-analyses were performed with grouping of studies by mutation status (i.e., BRCA1, BRCA2, CHEK2 c.1100delC), familial cohorts, and general population-based cohorts.

RESULTS

Sixty-eight papers satisfied our inclusion criteria. Strong associations with CBC were found for carrying a BRCA1 (RR = 3.7; 95%CI:2.8-4.9), BRCA2 (RR = 2.8; 95%CI:1.8-4.3) or CHEK2 c.1100delC (RR = 2.7; 95%CI:2.0-3.7) mutation. In population-based cohorts, PBC family history (RR = 1.8; 95%CI:1.2-2.6), body mass index (BMI) ≥30 kg/m² (RR = 1.5; 95%CI:1.3-1.9), lobular PBC (RR = 1.4; 95%CI:1.1-1.8), estrogen receptor-negative PBC (RR = 1.5; 95%CI:1.0-2.3) and treatment with radiotherapy <40 years (RR = 1.4; 95%CI:1.1-1.7) was associated with increased CBC risk. Older age at PBC diagnosis (RR per decade = 0.93; 95%CI:0.88-0.98), and treatment with chemotherapy (RR = 0.7; 95%CI:0.6-0.8) or endocrine therapy (RR = 0.6; 95%CI:0.5-0.7) were associated with decreased CBC risk.

CONCLUSIONS

Mutation status, family history, and PBC treatment are key factors for CBC risk. Age at PBC diagnosis, BMI, lobular histology and hormone receptor status have weaker associations and should be considered in combination with key factors to accurately predict CBC risk.

Nonaspirin NSAIDs and contralateral breast cancer risk

Laboratory studies suggest that inhibition of the cyclooxygenase (COX)-2 enzymes inhibits breast cancer development. We aimed to evaluate whether postdiagnosis use of COX-2 selective or other nonaspirin nonsteroidal anti-inflammatory drugs (NSAIDs) reduce the risk of contralateral breast cancer (CBC) among Danish breast cancer patients. From the clinical database of the Danish Breast Cancer Group, we identified 52,723 women diagnosed with breast cancer between 1996 and 2012. Data on nonaspirin NSAID use, CBC and potential confounding variables were obtained from nationwide registries. We defined postdiagnosis use (two or more prescriptions) as a time-varying covariate with a one-year lag. Cox proportional hazard regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for CBC associated with nonaspirin NSAID use. During a median follow-up of 4.8 years (interquartile range: 2.3-9 years), 1,444 patients were diagnosed with CBC. Overall, postdiagnosis use of nonaspirin NSAID was associated with an adjusted HR for CBC of 0.98 (95% CI: 0.87-1.11). The HRs did not vary substantially with duration or intensity of nonaspirin NSAID use. Moreover, similar associations were found for COX-2 selective (HR: 1.02; 95% CI: 0.85-1.23) and nonselective (HR: 0.96; 95% CI: 0.82-1.13) nonaspirin NSAIDs. In conclusion, our nationwide cohort study of breast cancer patients does not suggest a reduced risk of CBC with nonaspirin NSAID use regardless of the COX-2 selectivity.

Low-dose aspirin use and risk of contralateral breast cancer: a Danish nationwide cohort study

Observational studies of aspirin use and breast cancer risk have provided inconsistent results. The occurrence of contralateral breast cancer (CBC) among breast cancer survivors may serve as a useful high-risk model to identify preventive drug effects. Using this model, we examined the association between post-diagnosis use of low-dose aspirin and risk of CBC. We identified all women recorded with a first primary breast cancer in the Danish Breast Cancer Cooperative Group Database between 1996 and 2012. Information on drug use, tumor and patient characteristics, treatment, and CBC was obtained from nationwide registries. In the main analysis, we defined time-varying post-diagnosis low-dose aspirin use as two or more prescriptions filled during follow-up and applied a one-year exposure lag. Cox proportional hazard regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between post-diagnosis low-dose aspirin use and CBC risk. Among 52,723 breast cancer patients, 1,444 women developed CBC during a median follow-up of 4.8 years. The adjusted HR for CBC associated with post-diagnosis use of low-dose aspirin was 0.91 (95% CI: 0.75-1.09). We observed no substantial variation in HRs according to pattern of low-dose aspirin use or estrogen receptor status of the first or the contralateral breast cancer. In conclusion, this large nationwide cohort study of breast cancer survivors does not provide strong evidence suggesting an association between post-diagnosis use of low-dose aspirin and risk of CBC.

Mortality after contralateral breast cancer in Denmark

PURPOSE

How a second breast cancer diagnosis affects survival in comparison with unilateral breast cancer (UBC) is unclear. Prognostic factors for contralateral breast cancer (CBC) are also not well established. We aimed to investigate the survival pattern after CBC with particular focus on time between first and second breast cancer diagnosis and age at CBC diagnosis.

METHODS

Within the nationwide Danish Breast Cancer Cooperative Group database, we identified 68,466 breast cancer patients diagnosed during 1978-2012. Patients who subsequently developed CBC were identified in a previously established database (N = 3004). Patients were followed for breast cancer-specific death in the Danish Register of Causes of Death until 2015. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazard regression models. Cumulative breast cancer mortality from date of CBC was estimated using the Aalen-Johansen method.

RESULTS

Compared with UBC patients, the rate of dying from breast cancer was more than twofold higher following a CBC diagnosis, after adjustment for age, period, tumor characteristics, and treatment of the first breast cancer (HR 2.48; 95% CI 2.31-2.66). Short time interval (< 5 years) was associated with higher breast cancer-specific mortality after CBC among patients < 70 years at CBC diagnosis compared with longer time intervals, but not among patients ≥ 70 years at CBC diagnosis.

CONCLUSION

Breast cancer-specific mortality rates were markedly higher after compared with before a CBC diagnosis. We found higher breast cancer-specific mortality after CBC associated with a short interval between diagnoses among patients diagnosed with CBC before age 70 years.

Incidence of isolated local breast cancer recurrence and contralateral breast cancer: A systematic review

An increasing number of women is surviving breast cancer and due to that at risk of developing an isolated ipsilateral breast tumor recurrence (IBTR) or a contralateral breast cancer (CBC). Patients' main concern is cancer recurrence. Patient counseling on breast cancer recurrence is challenging. In order to provide healthcare professionals and patients more guidance, a systematic literature review of the incidence of isolated IBTR and CBC in women diagnosed with early invasive breast cancer was performed. Medline, EMBASE and the Cochrane Library were searched from 2000 until October 2015. Multicenter studies reporting an IBTR or CBC rate in curatively treated adult females diagnosed with invasive breast cancer were included. The initial search yielded 6998 potentially relevant articles. Twenty were eligible for inclusion, representing 25 recurrence incidence rates. Both isolated IBTR and CBC incidence rates steadily increased with the length of follow-up, indicating that IBTR and CBC occur even more than 15 years after diagnosis. The annual incidence rate of isolated IBTR and CBC in women diagnosed with an early invasive breast cancer was 0.6% (range: 0.4-1.1%) and 0.5% (range: 0.2-0.7%), respectively. Analyzed data were lacking information about important risk factors and given treatment with regard to the incidence of recurrence, which hampers the prediction of patient tailored recurrence risks. The presented rates are therefore the best available estimates of isolated IBTR and CBC annual incidence rates based on the current literature. Healthcare professionals could use these rates in their communication with patients diagnosed with early invasive breast cancer.

Dissecting Time- from Tumor-Related Gene Expression Variability in Bilateral Breast Cancer

Metachronous (MBC) and synchronous bilateral breast tumors (SBC) are mostly distinct primaries, whereas paired primaries and their local recurrences (LRC) share a common origin. Intra-pair gene expression variability in MBC, SBC, and LRC derives from time/tumor microenvironment-related and tumor genetic background-related factors and pairs represents an ideal model for trying to dissect tumor-related from microenvironment-related variability. Pairs of tumors derived from women with SBC (n = 18), MBC (n = 11), and LRC (n = 10) undergoing local-regional treatment were profiled for gene expression; similarity between pairs was measured using an intraclass correlation coefficient (ICC) computed for each gene and compared using analysis of variance (ANOVA). When considering biologically unselected genes, the highest correlations were found for primaries and paired LRC, and the lowest for MBC pairs. By instead limiting the analysis to the breast cancer intrinsic genes, correlations between primaries and paired LRC were enhanced, while lower similarities were observed for SBC and MBC. Focusing on stromal-related genes, the ICC values decreased for MBC and were significantly different from SBC. These findings indicate that it is possible to dissect intra-pair gene expression variability into components that are associated with genetic origin or with time and microenvironment by using specific gene subsets.

Low Lifetime Risk of Contralateral Breast Cancer in a Middle-Income Asian Country: Evidence to Guide Post-treatment Surveillance

BACKGROUND

The rate of contralateral risk-reducing mastectomy (CRRM) is increasing in the West with controversial evidence of improved survival in early breast cancer patients. Although uptake of CRRM in Asia appears low, the trends may rise, and there is currently an urgent need to provide evidence for informed decision-making in clinical practice. This study aims to determine the risk of contralateral breast cancer (CBC) and its associated factors in an Asian setting.

METHOD

A total of 2937 newly diagnosed patients with stage I and stage II breast cancer in University Malaya Medical Centre between Jan 1993 to Dec 2012 were included in the study. Multinomial logistic regression analysis allowing death to compete with CBC as a study outcome was used; patients with unilateral breast cancer who were alive were taken as reference. A stepwise backward regression analysis including age at diagnosis, ethnicity, family history of breast cancer, TNM stage, hormonal receptor status, HER2 status, chemotherapy, radiotherapy, and hormone therapy was conducted.

RESULTS

Fifty women developed CBC, over a median follow-up of 6 years. The 5- and 10-year cumulative risk of contralateral breast cancer was 1.0% (95% CI 0.6-1.4%) and 2.8% (95% CI 2.0-3.6%), respectively. Young age at diagnosis of first cancer, positive family history, and stage I disease were independent predictors of CBC.

DISCUSSION

The current study suggests that the risk of CBC is very low in a Southeast Asian setting. Any recommendations or practice of CRRM should be reviewed with caution and patients must be counseled appropriately.

Use of Surveillance Mammography Among Older Breast Cancer Survivors by Life Expectancy

Purpose The benefits of annual surveillance mammography in older breast cancer survivors with limited life expectancy are not known, and there are important risks; however, little is known about mammography use among these women. Materials and Methods We used National Health Interview Study data from 2000, 2005, 2008, 2010, 2013, and 2015 to examine surveillance mammography use among women age ≥ 65 years who reported a history of breast cancer. Using multivariable logistic regression, we assessed the probability of mammography within the last 12 months by 5- and 10-year life expectancy (using the validated Schonberg index), adjusting for survey year, region, age, marital status, insurance, educational attainment, and indicators of access to care. Results Of 1,040 respondents, 33.7% were age ≥ 80 years and 88.6% were white. Approximately 8.6% and 35.1% had an estimated life expectancy of ≤ 5 and ≤ 10 years, respectively. Overall, 78.9% reported having routine surveillance mammography in the last 12 months. Receipt of mammography decreased with decreasing life expectancy ( P < .001), although 56.7% and 65.9% of those with estimated ≤ 5-year and ≤ 10-year life expectancy, respectively, reported mammography in the last year. Conversely, 14.1% of those with life expectancy > 10 years did not report mammography. In adjusted analyses, lower ( v higher) life expectancy was significantly associated with lower odds of mammography (odds ratio, 0.4; 95% CI, 0.3 to 0.8 for ≤ 5-year life expectancy and OR, 0.4; 95% CI, 0.3 to 0.6 for ≤ 10-year life expectancy). Conclusion Many (57%) older breast cancer survivors with an estimated short life expectancy (< 5 years) receive annual surveillance mammography despite unknown benefits, whereas 14% with estimated life expectancy > 10 years did not report mammography. Practice guidelines are needed to optimize and tailor follow-up care for older patients.

Surveillance Mammography in Older Patients With Breast Cancer-Can We Ever Stop?: A Review

IMPORTANCE

Approximately 4% to 5% of breast cancer survivors will develop a new ipsilateral or contralateral cancer (in-breast event) over the 5 years following diagnosis, and annual surveillance mammography is recommended for those with residual breast tissue. The risk for such in-breast events persists over time, though increasing age at cancer diagnosis and treatment with hormonal therapy are associated with lower risk, and most older survivors of breast cancer will ultimately die from nonbreast cancer-related causes. Specific guidelines for surveillance strategies in older patients are limited. Prospective data on the benefits and harms of surveillance mammography in this population are lacking, and most of the evidence is derived from observational, retrospective data, often in the general population.

OBSERVATIONS

We review the current recommendations for breast cancer screening and surveillance for older patients, the current evidence for ipsilateral and contralateral breast cancer risks in older survivors of breast cancer, and suggested approaches for discussions about surveillance mammography with older patients. We recommend individualized decision making for surveillance breast imaging in older survivors of breast cancer, with consideration of the following strategy for women 70 years or older: 1-time imaging 6 to 12 months after completion of local therapy followed by annual or biennial surveillance mammography for healthy women and cessation of mammography in patients whose life expectancy is less than 5 years to 10 years, regardless of age. Decisions on mammographic surveillance should also incorporate whether hormonal therapy is being administered, whether a patient's anticipated life expectancy is extraordinary, and whether a patient's individual risk for in-breast events is higher (or lower) than average risk for breast cancer survivors.

CONCLUSIONS AND RELEVANCE

We propose reframing discussions around surveillance mammography in older breast cancer survivors and to consider cessation while taking into account life expectancy, the estimated risk for subsequent in-breast events, and patient preferences.