Hormone receptor status influences the locoregional benefit of trastuzumab in patients with nonmetastatic breast cancer

Population-level impact of adjuvant trastuzumab emtansine on the incidence of metastatic breast cancer: an epidemiological prediction model of women with HER2-positive early breast cancer and residual disease following neoadjuvant therapy

PURPOSE

Treating early-stage breast cancer (eBC) may delay or prevent subsequent metastatic breast cancer (mBC). In the phase 3 KATHERINE study, women with human epidermal growth factor receptor 2 (HER2)-positive eBC with residual disease following neoadjuvant therapy containing trastuzumab and a taxane experienced 50% reductions in disease recurrence or death when treated with adjuvant trastuzumab emtansine (T-DM1) vs adjuvant trastuzumab. We predicted the population-level impact of adjuvant T-DM1 on mBC occurrence in five European countries (EU5) and Canada from 2021-2030.

METHODS

An epidemiological prediction model using data from national cancer registries, observational studies, and clinical trials was developed. Assuming 80% population-level uptake of adjuvant treatment, KATHERINE data were extrapolated prospectively to model projections. Robustness was evaluated in alternative scenarios.

RESULTS

We projected an eligible population of 116,335 women in Canada and the EU5 who may be diagnosed with HER2-positive eBC and have residual disease following neoadjuvant therapy from 2021-2030. In EU5, the cumulative number of women projected to experience relapsed mBC over the 10-year study period was 36,009 vs 27,143 under adjuvant trastuzumab vs T-DM1, a difference of 8,866 women, equivalent to 25% fewer cases with the use of adjuvant T-DM1 in EU5 countries from 2021-2030. Findings were similar for Canada.

CONCLUSION

Our models predicted greater reductions in the occurrence of relapsed mBC with adjuvant T-DM1 vs trastuzumab in the indicated populations in EU5 and Canada. Introduction of T-DM1 has the potential to reduce population-level disease burden of HER2-positive mBC in the geographies studied.

Controversies of radiotherapy in human epidermal growth factor receptor (HER)-2 positive breast cancer patients

Tumor biology plays a crucial role in the systemic treatment, specifically in HER2-positive tumors. Distinct biological behavior of breast cancer subtypes is associated with different rates of locoregional recurrence (LRR). HER2- positive breast cancer patients treated with surgery in combination with radiation, without trastuzumab have poor outcome, including high LRR. The efficacy of radiotherapy in HER-2-positive breast cancer appears to be associated with the expression of estrogen receptors. In patients with HER-2-positive breast cancer, studies conducted before the introduction of trastuzumab indicated higher benefit of adjuvant radiation in patients with hormone receptor-positive tumors compared to patients with tumors not expressing hormone receptors. The introduction of agents targeting HER-2 has transformed the management of these patients, resulting in improved outcomes. The data of clinical studies show that the administration of trastuzumab as part of a multimodality approach (with radiation based on standard guidelines) results in improved outcomes, including lower locoregional recurrence. The risk of cardiac toxicity associated with radiation to the heart and administration of potential cardiotoxic trastuzumab is not clear. In patients treated concomitantly with regional lymph node irradiation and anti-HER-2 agents after prior anthracycline-based chemotherapy minimizing the dose to the myocardium, e.g. respiratory gating or proton beam radiotherapy, have been suggested.

Trastuzumab Provides a Comparable Prognosis in Patients With HER2-Positive Breast Cancer to Those With HER2-Negative Breast Cancer: Post Hoc Analyses of a Randomized Controlled Trial of Post-Mastectomy Hypofractionated Radiotherapy

Background and Purpose

We investigated the locoregional effect of trastuzumab, and determined whether patients with human epidermal growth factor receptor (HER)2-positive breast cancer (BC) treated with trastuzumab could achieve comparable efficacy to that of patients with HER2-negative BC.

Materials and Methods

This was post hoc analyses of data of 793 BC patients from a randomized controlled trial comparing post-mastectomy hypofractionated radiotherapy with conventional fractionated radiotherapy. Survival rates were analyzed by the Kaplan–Meier method and compared by the log-rank test.

Results

Patients were classified into three groups: HER2-negative (HER2⁻; n = 547), HER2-positve with trastuzumab (HER2⁺ + T; n = 136), and HER2-positive without trastuzumab (HER2⁺ − T; n = 110). The HER2⁺ + T group had significantly lower locoregional recurrence (LRR, 6.0% vs. 13.9%), distant metastasis (DM, 17.4% vs. 33.8%) and higher disease-free survival (DFS, 81.2% vs. 61.9%) at 5 years than that of the HER2⁺ − T group (P <.05). The HER2⁻ group had significantly lower LRR (6.8% vs. 13.9%), DM (22.4% vs. 33.8%) and higher DFS (76.1% vs. 61.9%) at 5 years than that of the HER2⁺ − T group (P <.05). The difference in LRR, DM and DFS at 5 years was not significant between the HER2⁺ + T group and HER2⁻ group (P >.05). Different annual LRR patterns was found among groups according to HR status.

Conclusion

Trastuzumab reduces LRR in patients with locally advanced HER2-positive BC who have received post-mastectomy radiotherapy. It provides comparable DFS to that with patients with HER2-negative BC.

Impact of Trastuzumab on Ipsilateral Breast Tumor Recurrence for Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer after Breast-Conserving Surgery

Purpose

Trastuzumab is effective in early and advanced human epidermal growth factor receptor 2 (HER2)-positive breast cancer. However, few studies have reported the effect of trastuzumab on ipsilateral breast tumor recurrence (IBTR), whose incidence is higher in the HER2-positive subtype than in other subtypes.

Methods

We retrospectively investigated 959 patients who underwent breast-conserving surgery (BCS), chemotherapy, and radiotherapy for HER2-positive breast cancer between 2000 and 2017. IBTR was compared between the patients who received neoadjuvant or adjuvant trastuzumab (Tmab group) for a total duration of 1 year and those who received no trastuzumab (N-Tmab group).

Results

Propensity score matching designated 426 and 142 patients in the Tmab and N-Tmab groups, respectively. The median follow-up period for all patients after matching was 73.79 months. The IBTR-free survival rate was significantly higher in the Tmab group than in the N-Tmab group (10-year IBTR-free survival rate, 92.9% vs. 87.3%; p = 0.002). The multivariate analysis showed a significant association between the N-Tmab and Tmab group (hazard ratio, 3.03; 95% confidence interval, 1.07–8.59) and IBTR in addition to close or positive resection margin and hormone receptor (HR) positivity. The subgroup analysis showed that adjuvant treatment with trastuzumab significantly reduced IBTR among the patients with HR-negative or lymph node-negative breast cancer.

Conclusion

Significantly reduced IBTR after BCS was observed in the patients who received 1 year of adjuvant/neoadjuvant trastuzumab treatment for HER2-positive breast cancer.

Effects of trastuzumab on locoregional recurrence in human epidermal growth factor receptor 2-overexpressing breast cancer patients treated with chemotherapy and radiotherapy

PURPOSE

In the present study, the ability of adjuvant trastuzumab to reduce locoregional recurrence in patients with human epidermal growth factor receptor 2 (HER2)-overexpressing breast cancer receiving adjuvant chemotherapy and radiotherapy (RT) was investigated.

MATERIALS AND METHODS

We retrospectively included 520 patients with HER2-overexpressing breast cancer who received surgery followed by adjuvant RT and cytotoxic chemotherapy from 2003 to 2011. Adjuvant trastuzumab was administered to 286 patients. Propensity score matching was conducted to compare trastuzumab-treated and non-treated cohorts.

RESULTS

Median follow-up duration was 7.1 years (range 1.1-14.1 years). Propensity score matching yielded 171 matched pairs of patients with no significantly different clinical factors. An improved 7-year locoregional control (LRC) rate was observed in the trastuzumab-treated cohort compared with the non-treated cohort (95.6% vs. 89.9%, p = 0.014). Based on multivariate analysis, hormone receptor negativity (hazard ratio [HR] = 5.348, p = 0.007), positive lymph node ratio > 0.25 (HR = 2.549, p = 0.040), and lack of adjuvant trastuzumab (HR = 3.401, p = 0.017) were identified as significant risk factors for poor LRC. Adjuvant trastuzumab significantly reduced the locoregional recurrence rate in patients with one or two risk factors (7-year LRC = 95.0% vs. 84.2%, p = 0.007); however, the benefit of adjuvant trastuzumab was non-significant in patients with no risk factors (7-year LRC = 95.8% vs. 97.9%, p = 0.75).

CONCLUSIONS

Adjuvant trastuzumab improved LRC in patients with HER2-overexpressing breast cancer receiving adjuvant RT and cytotoxic chemotherapy, especially in hormone receptor-negative, HER2-enriched subtype, and high positive lymph node ratio breast cancer.

Breast Cancer Biology: Clinical Implications for Breast Radiation Therapy

Historically, prognosis and treatment decision making for breast cancer patients have been dictated by the anatomic extent of tumor spread. However, in recent years, "breast cancer" has proven to be a collection of unique phenotypes with distinct prognoses, patterns of failure, and treatment responses. Recent advances in biologically based assays and targeted therapies designed to exploit these unique phenotypes have profoundly altered systemic therapy practice patterns and treatment outcomes. Data associating locoregional outcomes with tumor biology are emerging. However, the likelihood of obtaining level I evidence for fundamental radiation therapy questions within each of the specific subtypes in the immediate future is low. As such, this review aims to summarize the existing data and provide practical context for the incorporation of breast tumor biology into clinical practice.

Differential impact of hormone receptor status on survival and recurrence for HER2 receptor-positive breast cancers treated with Trastuzumab

INTRODUCTION

Hormone receptor status has major implications for treatment and survival of breast cancer. Yet the impact of hormone receptor status on outcome after Trastuzumab has received little attention. The objective here was to explore any differential effects of Trastuzumab treatment (Trast +ve) on Luminal B HER2 or HER2+(ER-) breast cancer subtypes.

METHODS

A cohort of 469 HER2 receptor-positive breast cancers was categorised by molecular subtype and Trastuzumab treatment. Effects of Trastuzumab treatment on survival, locoregional recurrence and distant metastasis were investigated by subtype, using univariate and multivariate analysis.

RESULTS

Trast +ve Luminal B HER2 patients had significant improvements in 5-year DFS (p < 0.001) and OS (p < 0.001), while Trast +ve HER2+(ER-) patients had significant improvements in 5-year DFS (p = 0.012) alone. Only Trast +ve Luminal B HER2 cancers displayed a significant reduction in LRR rates (p < 0.001). A significant reduction in distant metastasis rates was seen in Trast +ve Luminal B HER2 (p < 0.001) and HER2+(ER-) (p = 0.009) cancers. Interestingly, bone metastasis rates in Trast +ve Luminal B HER2 cancers demonstrated the greatest reduction (36.2-6.7%). Multivariate analysis of Trast +ve patients found no difference in distant metastasis rates (p = 0.96) between subtypes. Significantly, lower LRR rates were seen in Trast +ve Luminal B HER2 cancers, compared to Trast +ve HER2+(ER-) (p = 0.018).

CONCLUSION

An enhanced response to Trastuzumab was seen in Luminal B HER2 cancers. We highlight how Trastuzumab treatment changed the natural history of the HER2 receptor-positive breast cancer, demonstrating improved efficacy in changing the outcome of hormone receptor-positive patients.

How could breast cancer molecular features contribute to locoregional treatment decision making?

Systemic treatments are tailored to breast cancer (BC) heterogeneity, which is not yet taken into account for radiotherapy (RT) personalization. The primary objective of this review is to summarize existing data suggesting BC subtypes and genetic assays are prognostic and predictive biomarkers useful for RT decision-making and to provide implications for their incorporation into future translational and clinical research. The evidence suggesting that BC subtypes also exhibit distinct "locoregional recurrence (LRR)" patterns is retrospective but consistent and validated in over fifteen studies. The HER-2 positive and triple negative subtypes are the most susceptible to locoregional failure. The high risk of the HER-2 positive subtype can be reversed with trastuzumab administration. Very little is known on the subtypes' intrinsic radiosensitivity properties. Genetic assays have assessed retrospectively signatures' prognostic and predictive value in patients' cohorts (several coming from prospective studies) for LRR risk and radiotherapy (RT) benefit. Further confirmation is needed before their introduction into clinical routine. Evidence on the use of molecular biomarkers for adjuvant RT tailoring is emerging but needs validation and introduction into prospective studies. The plethora of modern RT options (partial breast irradiation, hypofractionation), as well as recent evidence pointing towards more extensive radiotherapy, demand introduction of biological features into clinical trials to improve therapeutic decisions. Open questions, such as tailoring of irradiation after neo-adjuvant chemotherapy in complete responders and the understanding of the interplay between local control, systemic recurrence and survival given modern systemic treatments, need to be addressed under the prism of biology within this heterogeneous disease. Intrinsic radiobiological properties within this heterogeneity need to be highlighted in order to further improve outcomes.

Trastuzumab improves locoregional control in HER2-positive breast cancer patients following adjuvant radiotherapy

The benefit of adjuvant trastuzumab in disease-free and overall survival for human epidermal receptor 2-positive (HER2+) breast cancer patients is well established. However, the effect of trastuzumab on locoregional control remains unclear, particularly in patients treated with adjuvant radiotherapy (RT). In this study, we investigated the locoregional benefit of trastuzumab in patients with HER2+ breast cancer after adjuvant RT.Using a single institutional database, we identified 278 patients with stage II/III invasive HER2+ breast tumors receiving adjuvant RT between January 2008 and July 2011. We compared the locoregional outcomes of 134 patients who received trastuzumab to 144 patients without trastuzumab within the same period. Clinical and biological factors that might impact on the locoregional benefit of trastuzumab were also assessed.At the median follow-up of 45 months, trastuzumab significantly lowered the risk of locoregional recurrence (LRR) with a 3-year LRR rate of 2.4% versus 7.5% for the cohort with and without trastuzumab (P = 0.019). Trastuzumab was associated with a more significant locoregional benefit in the hormone receptor-positive (HR+)/HER2+ subgroup, with a 3-year LRR of 0% versus 6.7% in the cohort with and without trastuzumab (P = 0.027). For HR-/HER2+ breast tumor patients, the 3-year LRR rate was still lower for the cohort with trastuzumab (4.7% vs 8.6%). However, statistical significance was not found (P = 0.179). Both univariate and multivariate analyses confirmed that trastuzumab treatment was the only significant predictive factor for LRR (hazard ratio, 4.05; 95% confidence interval, 1.07-15.35; P = 0.039).Adjuvant trastuzumab in addition to RT is associated with significant reduced LRR risk in HER2+ breast cancer.

Hormone receptor status does not alter the effect of trastuzumab in breast cancer

Overexpression of human epidermal growth factor receptor 2 (HER2) predicts response to anti-HER2 therapy in breast cancer. We investigated whether hormone receptor (HR) status influences the treatment benefit of trastuzumab in patients with breast cancer. Data from 8338 patients with primary nonmetastatic breast cancer from the cancer registry of Saxony-Anhalt Germany were analyzed. A total of 5554 patients were eligible for analysis. The median follow-up of the study was 6 years. Of the 5554 patients investigated, 1128 (20.3%) showed HER2 overexpression and 656 (58.2%) of them received adjuvant trastuzumab. The 10-year overall survival (OS) in the study cohort according to HR, HER2 status, and trastuzumab treatment was as follows: 78.4% for HR-/HER2-, 85.0% for HR+/HER2-, 70.4% HR-/HER2+/TRA-, 71.4% for HR+/HER2+/TRA-, 80.9% for HR-/HER2+/TRA+, and 89.2% for HR+/HER2+/TRA+. Trastuzumab treatment improved OS in the HR- patients only in the first 3 years, whereas in the HR+ group the effect of trastuzumab was still apparent 5 years after diagnosis. Notably, the relative improvement in a patient outcome was higher for HR+ patients. Nevertheless, matching for age, histological type, tumor stage, tumor grade, and performance status between patients with HR- and HR+ tumors demonstrated that the survival effect of trastuzumab was not affected by HR status; P=0.890. Trastuzumab treatment improves patients' survival regardless of HR status and should be offered to all HER2+ patients.

Identification of early breast cancer patient cohorts who may benefit from lapatinib therapy

In resource-constrained environments many patients with human epidermal growth factor receptor 2 (HER2)+ early breast cancer are currently not offered adjuvant anti-HER2 therapy. For patients who might be able to receive the tyrosine kinase inhibitor (TKI) lapatinib (e.g. after patent expiration), it is important to identify subgroups of patients for whom anti-HER2 TKI therapy could be beneficial. To do this, we used data from 2489 patients with centrally confirmed HER2+ disease enrolled in the adjuvant Tykerb Evaluation After Chemotherapy (TEACH) trial, investigating the effect of lapatinib in patients with HER2+ early breast cancer not treated with trastuzumab. We performed subgroup analyses and number-needed-to-treat (NNT) calculations using patient and tumour associated predictors. Hormone receptor negative (HR-) patients on lapatinib had a significantly prolonged disease-free survival (DFS) compared to HR- patients on placebo (hazard ratio 0.64, P=0.003). For patients with HR- disease, starting treatment with lapatinib ≤1 year from diagnosis improved DFS by 12.1% [2.1-22.1] at 2 years and 15.7% [4.1-27.2] at 5 years. Depending on lymph node status and time since diagnosis the NNT for recurrence (at 5 years) was between 5.9 (node positive patients <1 year from diagnosis) and 15.9. These numbers are in range with numbers reported for up-front adjuvant trastuzumab for HR unselected patients (e.g. 15.6 for DFS at 4 years in HERA). In a subgroup analysis of the adjuvant TEACH trial, we show that anti-HER2 monotherapy with a TKI is beneficial as adjuvant therapy in a subgroup of patients. NNT in HER2+ HR- patients are in range with those reported from up-front adjuvant trastuzumab trials.

Biological Subtype Predicts Risk of Locoregional Recurrence After Mastectomy and Impact of Postmastectomy Radiation in a Large National Database

PURPOSE

To evaluate locoregional recurrence (LRR) after mastectomy and impact of postmastectomy radiation (PMRT) by breast cancer subtype.

METHODS AND MATERIALS

Between 2000 and 2009, 5673 patients with stage I to III breast carcinoma underwent mastectomy and nodal evaluation; 30% received PMRT. Isolated LRR (iLRR) and LRR were compared across groups defined by biological subtype and receipt of trastuzumab: luminal A (estrogen [ER]/progesterone [PR]+, HER2-, low/intermediate grade), luminal B (ER/PR+, HER2-, high grade), HER2 with trastuzumab, HER2 without trastuzumab, and triple negative (TN; ER-, PR-, HER2-). LRR hazard ratios (HR) were estimated with multivariable Fine and Gray models. The effect of PMRT on LRR was evaluated with Fine and Gray models stratified by propensity for PMRT.

RESULTS

With a median follow-up time of 50.1 months, there were 19 iLRR and 109 LRR events. HER2 patients with trastuzumab had no iLRR and only a single LRR. Compared with luminal A patients, TN patients had significantly greater adjusted risk of iLRR (HR 14.10; 95% CI 2.97%-66.90%), with a similar trend among luminal B (HR 4.94; 95% CI 0.94%-25.82%) and HER2 patients without trastuzumab (HR 4.41; 95% CI 0.61%-32.11%). Although PMRT reduced LRR, the effect of PMRT varied by subgroup, with the greatest and smallest effects seen among luminal A (HR 0.17; 95% CI 0.05%-0.62%) and TN patients (HR 0.59; 95% CI 0.25%-1.35%), respectively.

CONCLUSIONS

TN patients had the highest risk of LRR and the least benefit from PMRT; these patients may benefit from alternative treatment strategies. In contrast, in the era of HER2-directed therapy, the role of local therapy may need to be reassessed among HER2 patients.

Effect of margin width on local recurrence in triple-negative breast cancer patients treated with breast-conserving therapy

BACKGROUND

The effect of increasing negative margin width after breast-conserving therapy (BCT) on local recurrence (LR) is controversial. LR rates vary by subtype, with the highest rates seen in triple-negative breast cancer (TNBC). This study examined LR rates in relationship to margin width in TNBC treated with BCT.

METHODS

Women with TNBC who underwent BCT between 1999 and 2009 were identified. Margins were defined as positive (ink on tumor), 0.1-2.0, and 2 mm. Patients with positive margins were excluded. Statistical comparisons were by t test, Fisher's exact test, and Wilcoxon rank sum test. Cumulative incidence of LR was compared by competing-risks methodology.

RESULTS

Of 535 cancers, 71 had margins ≤2 mm and 464 had margins >2 mm. At a median follow-up of 84 months (range 8-165 months), there were 37 local, 18 regional, and 77 distant recurrences or deaths as first events. Ten patients had a locoregional recurrence before planned radiotherapy and were excluded from cumulative incidence analyses. The cumulative incidence of LR at 60 months for margins ≤2 mm was 4.7 % (95 % confidence interval 0-10.0) and for >2 mm was 3.7 % (1.8, 5.5) (p = 0.11). After controlling for chemotherapy and tumor size, there was no difference in LR between the two margin groups (p = 0.06). A difference in the risk of distant recurrence or death was not observed (p = 0.53).

CONCLUSIONS

Margin width of >2 mm was not associated with reduced LR rates. These data support a negative margin definition of no ink on tumor, even in this high-risk TNBC cohort.

Local recurrence following breast-conserving treatment in women aged 40 years or younger: trends in risk and the impact on prognosis in a population-based cohort of 1143 patients

AIM

To evaluate trends in the risk of local recurrences after breast-conserving treatment (BCT) and to examine the impact of local recurrence (LR) on distant relapse-free survival in a large, population-based cohort of women aged ≤40 years with early-stage breast cancer.

METHODS

All women (n=1143) aged ≤40 years with early-stage (pT1-2/cT1-2, N0-2, M0) breast cancer who underwent BCT in the south of the Netherlands between 1988 and 2010 were included. BCT consisted of local excision of the tumour followed by irradiation of the breast.

RESULTS

After a median follow-up of 8.5 (0.1-24.6)years, 176 patients had developed an isolated LR. The 5-year LR-rate for the subgroups treated in the periods 1988-1998, 1999-2005 and 2006-2010 were 9.8% (95% confidence interval (CI) 7.1-12.5), 5.9% (95% CI 3.2-8.6) and 3.3% (95% CI 0.6-6.0), respectively (p=0.006). In a multivariate analysis, adjuvant systemic treatment was associated with a reduced risk of LR of almost 60% (hazard ratio (HR) 0.42; 95%CI 0.28-0.60; p<0.0001). Patients who experienced an early isolated LR (≤5 years after BCT) had a worse distant relapse-free survival compared to patients without an early LR (HR 1.83; 95% CI 1.27-2.64; p=0.001). Late local recurrences did not negatively affect distant relapse-free survival (HR 1.24; 95% CI 0.74-2.08; p=0.407).

CONCLUSION

Local control after BCT improved significantly over time and appeared to be closely related to the increased use and effectiveness of systemic therapy. These recent results underline the safety of BCT for young women with early-stage breast cancer.