The Impact of Primary Tumor Surgery on Survival in HER2 Positive Stage IV Breast Cancer Patients in the Current Era of Targeted Therapy

Guidance for Canadian Breast Cancer Practice: National Consensus Recommendations for the Systemic Treatment of Patients with HER2+ Breast Cancer in Both the Early and Metastatic Setting

Human epidermal growth factor receptor 2-positive (HER2+) breast cancer is an aggressive subtype of breast cancer associated with a poor prognosis when sub-optimally treated. Recent advances include new and effective targeted therapies that have significantly improved outcomes for patients. Despite these advances, there are significant gaps across Canada, underscoring the need for evidence-based consensus guidance to inform treatment decisions. Addressing these gaps is crucial to ensuring that effective therapies are integrated into clinical practice, so as to improve the lives of patients affected by this aggressive form of breast cancer. The Research Excellence, Active Leadership (REAL) Canadian Breast Cancer Alliance is a standing nucleus committee of clinical-academic oncologists across Canada and Breast Cancer Canada, a patient organization. The mandate of this group is to provide evidence-based guidance on best practices in the management of patients with breast cancer. These consensus recommendations were developed using a modified Delphi process with up to three rounds of anonymous voting. Consensus was defined a priori as ≥75% of voters agreeing with the recommendation as written. There are 9 recommendations in the early setting; 7 recommendations in the metastatic setting; and 10 recommendations for patients with brain metastases.

Distinguishing optimal candidates for primary tumor resection in patients with metastatic lung adenocarcinoma: A predictive model based on propensity score matching

Background

Primary tumor resection is associated with survival benefits in patients with metastatic lung adenocarcinoma (mLUAD). However, there are no established methods to determine which individuals would benefit from surgery. Therefore, we developed a model to predict the patients who are likely to benefit from surgery in terms of survival.

Methods

Data on patients with mLUAD were extracted from the Surveillance, Epidemiology, and End Results (SEER) database. Depending on whether surgery was performed on the primary tumor, patients were categorized into two groups: cancer-directed surgery (CDS) and no-cancer-directed surgery (No-CDS). Propensity Score Matching (PSM) was utilized to address bias between the CDS and No-CDS groups. The prognostic impact of CDS was assessed using Kaplan-Meier analysis and Cox proportional hazard models. Subsequently, we constructed a nomogram to predict the potential for surgical benefits based on multivariable logistic regression analysis using preoperative factors.

Results

A total of 89,039 eligible patients were identified, including 6.4% (5705) who underwent surgery. Following PSM, the CDS group demonstrated a significantly longer median overall survival (mOS) compared with the No-CDS group (23 [21-25] vs. 7 [7-8] months; P < 0.001). The nomogram showed robust performance in both the training and validation sets (area under the curve [AUC]: 0.698 and 0.717, respectively), and the calibration curves exhibited high consistency. The nomogram proved clinically valuable according to decision curve analysis (DCA). According to this nomogram, surgical patients were categorized into two groups: no-benefit candidates and benefit candidates groups. Compared with the no-benefit candidate group, the benefit candidate group was associated with longer survival (mOS: 25 vs. 6 months, P < 0.001). Furthermore, no difference in survival was observed between the no-benefit candidates and the no-surgery groups (mOS: 6 vs. 7 months, P = 0.9).

Conclusions

A practical nomogram was developed to identify optimal CDS candidates among patients with mLUAD.

Systemic Treatment of Patients With Metastatic Breast Cancer: ASCO Resource-Stratified Guideline

PURPOSE

To guide clinicians and policymakers in three global resource-constrained settings on treating patients with metastatic breast cancer (MBC) when Maximal setting-guideline recommended treatment is unavailable.

METHODS

A multidisciplinary, multinational panel reviewed existing ASCO guidelines and conducted modified ADAPTE and formal consensus processes.

RESULTS

Four published resource-agnostic guidelines were adapted for resource-constrained settings; informing two rounds of formal consensus; recommendations received ≥75% agreement.

RECOMMENDATIONS

Clinicians should recommend treatment according to menopausal status, pathological and biomarker features when quality results are available. In first-line, for hormone receptor (HR)-positive MBC, when a non-steroidal aromatase inhibitor and CDK 4/6 inhibitor combination is unavailable, use hormonal therapy alone. For life-threatening disease, use single-agent chemotherapy or surgery for local control. For premenopausal patients, use ovarian suppression or ablation plus hormone therapy in Basic settings. For human epidermal growth factor receptor 2 (HER2)-positive MBC, if trastuzumab, pertuzumab, and chemotherapy are unavailable, use trastuzumab and chemotherapy; if unavailable, use chemotherapy. For HER2-positive, HR-positive MBC, use standard first-line therapy, or endocrine therapy if contraindications. For triple-negative MBC with unknown PD-L1 status, or if PD-L1-positive and immunotherapy unavailable, use single-agent chemotherapy. For germline BRCA1/2 mutation-positive MBC, if poly(ADP-ribose) polymerase inhibitor is unavailable, use hormonal therapy (HR-positive MBC) and chemotherapy (HR-negative MBC). In second-line, for HR-positive MBC, Enhanced setting recommendations depend on prior treatment; for Limited, use tamoxifen or chemotherapy. For HER2-positive MBC, if trastuzumab deruxtecan is unavailable, use trastuzumab emtansine; if unavailable, capecitabine and lapatinib; if unavailable, trastuzumab and/or chemotherapy (hormonal therapy alone for HR-positive MBC).Additional information is available at www.asco.org/resource-stratified-guidelines. It is ASCO's view that healthcare providers and system decision-makers should be guided by the recommendations for the highest stratum of resources available. The guideline is intended to complement but not replace local guidelines.

Survival nomograms for colorectal carcinoma patients with lung metastasis and lung-only metastasis, based on the SEER database and a single-center external validation cohort

Background

We analysed the survival of colorectal cancer (CRC) patients with lung metastasis and lung-only metastasis and determined the risk factors for lung metastasis in CRC patients.

Methods

Data from colorectal cancer patients with lung metastasis diagnosed from 2010 to 2015 were obtained from the SEER database. Survival was analysed using the Kaplan–Meier method and log-rank test, the Cox proportional hazards regression model, and a competing risk model. The predictive ability of the nomgram was assessed by the concordance index (C-index) and calibration curves. The data from the SEER database for the period 2016–2019 was used as an external validation set. The characteristics of 70 CRC patients treated at Shanghai East Hospital between 2016 and 2019 were retrospectively analysed and data from China was chosen as an external validation set.

Results

The median survival time for colorectal cancer patients with lung metastasis was 12 months, while this value was 24 months in patients with lung-only metastasis. Among all CRC patients with lung metastasis, age, grade, T stage, N stage, presence of liver, brain or bone metastasis, anatomic site and surgery were related to overall survival (OS). In CRC patients with lung-only metastasis, age, T stage, marital status, chemotherapy and surgery were independent prognostic factors affecting OS. Two nomograms predicting OS were established, with great discrimination (C-index between 0.67 and 0.81) and excellent calibration. Factors including age, race, sex, tumour grade, T stage, N stage, presence of liver, brain or bone metastasis, marital status, insurance status and anatomic location were related to the occurrence of lung metastasis in CRC patients.

Conclusion

We developed two reliable clinical prediction models among CRC patients to predict the OS rates in patients with lung metastasis and lung metastasis only.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-022-02547-9.

The Timing, the Treatment, the Question: Comparison of Epidemiologic Approaches to Minimize Immortal Time Bias in Real-World Data Using a Surgical Oncology Example

BACKGROUND

Studies evaluating the effects of cancer treatments are prone to immortal time bias that, if unaddressed, can lead to treatments appearing more beneficial than they are.

METHODS

To demonstrate the impact of immortal time bias, we compared results across several analytic approaches (dichotomous exposure, dichotomous exposure excluding immortal time, time-varying exposure, landmark analysis, clone-censor-weight method), using surgical resection among women with metastatic breast cancer as an example. All adult women diagnosed with incident metastatic breast cancer from 2013-2016 in the National Cancer Database were included. To quantify immortal time bias, we also conducted a simulation study where the "true" relationship between surgical resection and mortality was known.

RESULTS

24,329 women (median age 61, IQR 51-71) were included, and 24% underwent surgical resection. The largest association between resection and mortality was observed when using a dichotomized exposure [HR, 0.54; 95% confidence interval (CI), 0.51-0.57], followed by dichotomous with exclusion of immortal time (HR, 0.62; 95% CI, 0.59-0.65). Results from the time-varying exposure, landmark, and clone-censor-weight method analyses were closer to the null (HR, 0.67-0.84). Results from the plasmode simulation found that the time-varying exposure, landmark, and clone-censor-weight method models all produced unbiased HRs (bias -0.003 to 0.016). Both standard dichotomous exposure (HR, 0.84; bias, -0.177) and dichotomous with exclusion of immortal time (HR, 0.93; bias, -0.074) produced meaningfully biased estimates.

CONCLUSIONS

Researchers should use time-varying exposures with a treatment assessment window or the clone-censor-weight method when immortal time is present.

IMPACT

Using methods that appropriately account for immortal time will improve evidence and decision-making from research using real-world data.

Exploring the Value of Additional Primary Tumour Excision Combined with Systemic Therapy Administered in Different Sequences for Patients with de Novo Metastatic Breast Cancer

Introduction

Uncertainty still remains regarding the survival improvement derived from immediate surgery or subsequent surgery in addition to systemic therapy for patients with de novo metastatic breast cancer. The current study aimed to examine the effect of combined treatment administered in different sequences on the survival of these patients.

Materials and Methods

We conducted a retrospective cohort study of patients with de novo stage IV breast cancer in the Surveillance, Epidemiology, and End Results (SEER) database from 2010 to 2019. Patients were categorized into 3 groups: (1) systemic therapy without primary surgery, (2) systemic therapy after primary surgery, and (3) systemic therapy before primary surgery. Cumulative incidence curves with Gray's test were used to compare breast cancer-specific death (BCSD) between groups. Kaplan–Meier curves with the log-rank test were applied to compare overall survival (OS) between groups. A competing risk model and a proportional hazards model were generated to adjust for important prognostic factors. Propensity score matching (PSM) was performed in the primary survival analysis. Stratified analysis was also performed.

Results

Patients who underwent systemic therapy after primary surgery and who underwent systemic therapy before primary surgery both showed a significantly reduced risk of BCSD compared to patients who received systemic therapy without primary surgery [subdistribution hazard ratio (SHR): 0.74; 95% confidence interval (CI): 0.69–0.79; and P < 0.001, and SHR: 0.62; 95% CI: 0.56–0.67; and P < 0.001, respectively]. A statistically significant disparity was also noted in OS. In the setting of single-organ metastasis, including the bone, lung, and liver, patients receiving the combination therapy showed an improved prognosis compared with patients receiving systemic therapy without primary surgery.

Conclusions

Additional primary tumour excision, whether before or after systemic therapy, may provide survival benefits for patients presenting with de novo metastatic breast cancer, especially for patients with single-organ disease involving the bone, lung, and liver but not the brain. Further investigations mainly focused on these carefully selected candidates are required to improve personalized treatment for metastatic breast cancer.

Clinical outcomes and a nomogram for de novo metastatic breast cancer with lung metastasis: a population-based study

To better understand the clinical characteristics of newly diagnosed lung metastatic breast cancer (LMBC) and quantify its prognosis, we retrieved data on patients with LMBC from the Surveillance, Epidemiology, and End Results database. Eligible patients were randomly assigned to training and validation cohorts (ratio 7:3) to establish a nomogram using the Cox proportional hazards regression model. In total, 4310 patients with LMBC were enrolled, including 52.4% (2259/4310) HR+/HER2-, 17.6% (757/4310) HR+/HER2+, 10.8% (467/4310) HR-/HER2+, and 19.2% (827/4310) HR-/HER2- subtype patients. Inclinations of lung and brain involvement in HR-/HER2+ and HR-/HER2- subgroups, liver involvement in the HER2 overexpressing subgroup, and bone involvement in the HR-positive subgroup were detected in the LMBC population. Regarding prognosis, HR+/HER2+ subtype patients presented the most favorable profile (mOS 35.0 months, 95% CI 30.1-39.9), while HR-/HER2- patients exhibited the worst (mOS 11.0 months, 95% CI, 10.0-11.9). A nomogram was developed in the training cohort and validated internally (C-index 0.70) and externally (C-index 0.71), suggestive of decent performance. This study assessed the clinical outcomes associated with molecular subtypes, metastatic patterns, and surgical intervention and provided a robust nomogram for the estimation of survival probabilities, which are promising for the management of LMBC in clinical practice.

Prognostic factors and survival prediction in HER2-positive breast cancer with bone metastases: A retrospective cohort study

BACKGROUND

Bone is the most common metastatic site of breast cancer. The developmental pattern of bone metastasis differs in different molecular subtypes. The prognostic factors of HER2-positive breast cancer with bone metastases require further investigation. The goal of this retrospective study was to identify the clinical features and prognostic factors for HER2-positive patients with bone metastases.

METHODS

A total of 34,084 HER2-positive breast cancer cases and 1204 cases of bone metastases from the Surveillance, Epidemiology, and End Results (SEER) database from 2010 to 2015 were analyzed to identify clinical characteristics and prognostic factors. A nomogram was constructed based on the Cox proportional hazards regression model. The C-index, calibration curve, and receiver operating characteristic (ROC) were utilized for model validation.

RESULTS

In the HER2-positive breast cancer total population (34,084 cases), 6.2% developed metastatic diseases. Bone metastases accounted for 3.5% of the entire cohort and 56.7% of all metastatic cases. Univariate and multivariate Cox regression analyses identified seven prognostic factors for predicting cancer-specific survival (CSS) for HER2-positive breast cancer patients with bone metastases, including age, brain metastases, liver metastases, lung metastases, PR status, surgery, and chemotherapy. The C-index of the nomogram was 0.74 vs. 0.78 (for 3-year CSS) and 0.77 vs. 0.81 (for 5-year CSS) in the model and validation cohorts, respectively. The AUCs were 0.74 vs. 0.78 (for 3-year CSS) and 0.77 vs. 0.81 (for 5-year CSS) in the model and validation cohorts, respectively. The calibration curves indicated favorable agreement between the actual observations and the predictions.

CONCLUSION

Our study provided population-based clinical features and prognostic factors for HER2-positive breast cancer patients with bone metastases and we constructed a prognostic nomogram with reliable accuracy.

Primary Surgery with Systemic Therapy in Patients with de Novo Stage IV Breast Cancer: 10-year Follow-up; Protocol MF07-01 Randomized Clinical Trial

BACKGROUND

The aim of this randomized clinical trial was to evaluate the overall survival (OS) data of patients diagnosed with de novo stage IV breast cancer (BC) who received locoregional treatment (LRT) over a 10-year follow-up.

STUDY DESIGN

The MF07-01 is a 1:1 multicenter, randomized clinical trial comparing the LRT with systemic therapy (ST), where ST was given to all patients either immediately after randomization or after surgical resection of the intact primary tumor.

RESULTS

A total of 278 patients were randomized and 265 patients were in the final analysis. At 10-year follow-up, survivals were 19% (95% CI 13%-28%) and 5% (95% CI 2%-12%) in the LRT group and ST group, respectively. Median survival was 46 months for the LRT group and 35 months for the ST group, and hazard of death was 29% lower in the LRT group compared with the ST group (hazard ratio [HR] 0.71; 95% CI 0.59-0.86; p = 0.0003).

CONCLUSIONS

Patients with a diagnosis of de novo stage IV BC who underwent LRT followed by ST had a 14% higher chance of OS by the end of the 10-year follow-up compared with the patients who received only ST. The longer study follow-up revealed that LRT should be presented to patients when discussing treatment options.

Debulking surgery for malignant tumors: the current status, evidence and future perspectives

Debulking surgery, also called cytoreductive surgery, is a resection of the tumor as much as possible and an intended incomplete resection for unresectable malignant tumors. Since the most important principle in surgical oncology is complete R0 resection, debulking surgery goes against the basic principle and obscures the concept of operability. However, debulking surgery has been advocated for various types of advanced malignant tumors, including gynecological cancers, urological cancers, gastrointestinal cancers, breast cancers and other malignancies, with or without adjuvant therapy. Positive data from randomized trials have been shown in subsets of ovarian cancer, renal cell carcinoma, colorectal cancer and breast cancer. However, recent trials for renal cell carcinoma, colorectal cancer and breast cancer have tended to show controversial results, mainly according to the survival improvement of nonsurgical systemic therapy alone. On the other hand, debulking surgery still has a therapeutic role for slow-growing and borderline malignant tumors, such as pseudomyxoma peritonei and thymomas. The recent understanding of tumor heterogeneity and clonal evolution responsible for malignancy and drug resistance indicates that select patients may obtain prolonged survival by the synergistic effect of debulking surgery and novel systemic therapy. This review aimed to describe the current status and evidence of debulking surgery in a cross-organ manner and to discuss future perspectives in the current era with advances in systemic therapy.

Breast cancer

Breast cancer is still the most common cancer worldwide. But the way breast cancer is viewed has changed drastically since its molecular hallmarks were extensively characterised, now including immunohistochemical markers (eg, ER, PR, HER2 [ERBB2], and proliferation marker protein Ki-67 [MKI67]), genomic markers (eg, BRCA1, BRCA2, and PIK3CA), and immunomarkers (eg, tumour-infiltrating lymphocytes and PD-L1). New biomarker combinations are the basis for increasingly complex diagnostic algorithms. Neoadjuvant combination therapy, often including targeted agents, is a standard of care (especially in HER2-positive and triple-negative breast cancer), and the basis for de-escalation of surgery in the breast and axilla and for risk-adapted post-neoadjuvant strategies. Radiotherapy remains an important cornerstone of breast cancer therapy, but de-escalation schemes have become the standard of care. ER-positive tumours are treated with 5-10 years of endocrine therapy and chemotherapy, based on an individual risk assessment. For metastatic breast cancer, standard therapy options include targeted approaches such as CDK4 and CDK6 inhibitors, PI3K inhibitors, PARP inhibitors, and anti-PD-L1 immunotherapy, depending on tumour type and molecular profile. This range of treatment options reflects the complexity of breast cancer therapy today.

The Effect of Primary Surgery in Patients with De Novo Stage IV Breast Cancer with Bone Metastasis Only (Protocol BOMET MF 14-01): A Multi-Center, Prospective Registry Study

BACKGROUND

More evidence shows that primary surgery for de novo metastatic breast cancer (BC) prolongs overall survival (OS) in selected cases. The aim of this study was to evaluate the role of locoregional treatment (LRT) in BC patients with de novo stage IV bone only metastasis (BOM).

METHODS

The prospective, multicenter registry study BOMET MF14-01 was initiated in May 2014. Patients with de novo stage IV BOM BC were divided into two groups: those receiving systemic treatment (ST group) and those receiving LRT (LRT group). Patients who received LRT were further divided into two groups: ST after LRT (LRT + ST group) and ST before LRT (ST + LRT group).

RESULTS

We included 505 patients in this study; 240 (47.5%) patients in the ST group and 265 (52.5%) in the LRT group. One hundred and thirteen patients (26.3%) died in the 34-month median follow-up, 85 (35.4%) in the ST group and 28 (10.5%) in LRT group. Local progression was observed in 39 (16.2%) of the patients in the ST group and 18 (6.7%) in the LRT group (p = 0.001). Hazard of death was 60% lower in the LRT group compared with the ST group (HR 0.40, 95% CI 0.30-0.54, p < 0.0001).

CONCLUSION

In this prospectively maintained registry study, we found that LRT prolonged survival and decreased locoregional recurrence in the median 3-year follow-up. Timing of primary breast surgery either at diagnosis or after ST provided a survival benefit similar to ST alone in de novo stage IV BOM BC patients.

A population-based predictive model predicting candidate for primary tumor surgery in patients with metastatic esophageal cancer

Background

The survival benefit of primary tumor surgery for metastatic esophageal cancer (mEC) patients has been observed, but methods for discriminating which individual patients would benefit from surgery have been poorly defined. Herein, a predictive model was developed to test the hypothesis that only certain metastatic patients would gain a survival benefit from primary tumor surgery.

Methods

Clinical data for patients with mEC were extracted from the Surveillance, Epidemiology and End Results (SEER) database [2004-2016] and then divided into surgery and no-surgery groups according to whether surgery was performed on the primary tumor. Propensity-score-matching (PSM) was performed to balance the confounding factors. We hypothesized that the patients who had undergone surgery and lived longer than the median cancer-specific-survival (CSS) of the no-surgery group could benefit from surgery. We constructed a nomogram to predict surgery benefit potential based on multivariable logistic-regression analysis using preoperative factors. The predictive performance of the nomogram was evaluated by the area under the receiver operating characteristic (AUC) and calibration curves. The clinical application value of the nomogram was estimated with decision curve analysis (DCA).

Results

A total of 5,250 eligible patients with mEC were identified, and 9.4% [492] received primary tumor surgery. After PSM, CSS for the surgery group was significantly longer [median: 19 vs. 9 months; hazard ratio (HR) 0.52, P<0.001] compared with the no-surgery group. Among the surgery group, 69.3% [327] survived >9 months (surgery-beneficial group). The prediction nomogram showed good discrimination both in training and validation sets (AUC: 0.72 and 0.70, respectively), and the calibration curves indicated a good consistency. DCA demonstrated that the nomogram was clinically useful. According to this nomogram, surgery patients were classified into two groups: no-benefit-candidate and benefit-candidate. The benefit-candidate group was associated with longer survival than the no-benefit-candidate group (median CSS: 19 vs. 6.5 months, P<0.001). Additionally, there was no difference in survival between the no-benefit-candidate and no-surgery groups (median CSS: 6.5 vs. 9 months, P=0.070).

Conclusions

A predictive model was created for the selection of candidates for surgical treatment among mEC patients. This predictive model might be used to select patients who may benefit from primary tumor surgery.

Benefits of Surgical Treatment of Stage IV Breast Cancer for Patients With Known Hormone Receptor and HER2 Status

BACKGROUND

For the 6% of breast cancer patients with a diagnosis of stage IV disease, systemic therapy is the cornerstone of treatment, with an unclear role for surgery. Limited evidence exists to delineate treatment methods with regard to hormone receptor and human epidermal growth factor receptor 2 (HER2) status.

METHODS

The National Cancer Database was used to identify 12,838 stage IV breast cancer patients with known hormone receptor and HER2 status from 2010 to 2015. Chi square tests examined subgroup differences between the treatment methods received. Using the Kaplan-Meier method, 5-year overall survival (OS) was assessed. Multivariate Cox proportional hazard models examined factors associated with survival.

RESULTS

A survival advantage was noted for patients who received either systemic therapy and surgery (ST + Surg: hazard ratio [HR] 0.723; 95% confidence interval [CI] 0.671-0.779) or systemic therapy, surgery, and radiation (Trimodality: HR 0.640; 95% CI 0.591-0.694) (both p < 0.0001) compared with systemic therapy alone (ST). The HER2+ patients who received Trimodality or ST + Surg had a better 5-year OS rate than those who received ST (Trimodality [48%], ST + Surg [41%], ST [29%]; p < 0.0001). The sequence of chemotherapy in relation to surgery is significant, with the greatest survival advantage noted for recipients of neoadjuvant chemotherapy (NAC) compared with patients who had adjuvant chemotherapy when they had positive hormone receptor and HER2 status (HER2 + NAC: HR 0.477; estrogen receptor-positive [ER+] NAC: HR 0.453; progesterone receptor-positive [PR+] NAC: HR 0.448; all p < 0.0001).

CONCLUSIONS

Surgery in addition to ST has a survival benefit for stage IV breast cancer patients with known hormone receptor and HER2 status and should be considered after NAC for patients with ER+, PR+, or HER2+ disease.

Development of an Individualized Prediction Calculator for the Benefit of Postoperative Radiotherapy in Patients with Surgically Resected De Novo Stage IV Breast Cancer

PURPOSE

Locoregional treatment has been increasingly adopted for metastatic breast cancer at presentation. This study aims to develop an individualized calculator to predict the benefit of postoperative radiotherapy (PORT) for patients with surgically resected de novo stage IV breast cancer.

METHODS AND MATERIALS

We searched the Surveillance, Epidemiology, and End Results (SEER) database for patients diagnosed with stage IV breast cancer between 2010 and 2014. After applying exclusion criteria, a total of 4473 patients were included in the analysis. Propensity score matching was used to balance the individual characteristics of the patients. After identifying the significant prognosticators, a nomogram was developed using multivariate regression models and internally validated. A web-based calculator was then constructed using a fitted survival prediction model.

RESULTS

With a median follow-up of 34 months, the three-year overall survival (OS) rates were 54.1% in the surgery alone group and 63.5% in the surgery + PORT group (p < 0.001). The survival benefit of PORT was maintained after propensity score matching (p < 0.001). Interaction testing of the prognostic variables found significant interactions between PORT and the presence of brain metastasis (p = 0.001), and between PORT and hormonal receptor expression (p = 0.018). After reviewing the performance of various models, a log-normal distributed survival model was adopted, with a C-index of 0.695. A calibration plot verified that the predicted survival rates were strongly correlated with the actual OS rates. A web-based survival calculator was constructed to provide individualized estimates of survival according to PORT.

CONCLUSION

PORT significantly improved OS rates, though the individual benefit was affected by a number of factors. We successfully developed a nomogram and web-based calculator that predicted the prognosis according to PORT in patients with surgically resected de novo stage IV breast cancer. These tools are expected to be useful in clinical practice and in the design of related trials.