Potential reduction of contralateral second breast-cancer risks by prophylactic mammary irradiation: validation in a breast-cancer-prone mouse model

Novel Cancer Prevention Strategies in Individuals With Hereditary Cancer Syndromes: Focus on BRCA1, BRCA2, and Lynch Syndrome

Germline pathogenic variants (PVs) in the BRCA1 and BRCA2 genes confer elevated risks of breast, ovarian, and other cancers. Lynch syndrome (LS) is associated with increased risks of multiple cancer types including colorectal and uterine cancers. Current cancer risk mitigation strategies have focused on pharmacologic risk reduction, enhanced surveillance, and preventive surgeries. While these approaches can be effective, they stand to be improved on because of either limited efficacy or undesirable impact on quality of life. The current review summarizes ongoing investigational efforts in cancer risk prevention strategies for patients with germline PVs in BRCA1, BRCA2, or LS-associated genes. These efforts span radiation, surgery, and pharmacology including vaccine strategies. Understanding the molecular events involved in the premalignant to malignant transformation in high-risk individuals may ultimately contribute significantly to novel prevention strategies.

A New Systemic Disease Mouse Model for Glioblastoma Capable of Single-Tumour-Cell Detection

BACKGROUND

Glioblastoma is characterised by extensive infiltration into the brain parenchyma, leading to inevitable tumor recurrence and therapeutic failure. Future treatments will need to target the specific biology of tumour recurrence, but our current understanding of the underlying mechanisms is limited. Significantly, there is a lack of available methods and models that are tailored to the examination of tumour recurrence.

METHODS

NOD-SCID mice were orthotopically implanted with luciferase-labelled donor U87MG or MU20 glioblastoma cells. Four days later, an unlabelled recipient tumor was implanted on the contralateral side. The mice were euthanised at a humane end-point and tissue and blood samples were collected for ex vivo analyses.

RESULTS

The ex vivo analyses of the firefly-labelled MU20 tumours displayed extensive invasion at the primary tumour margins, whereas the firefly-labelled U87MG tumours exhibited expansive phenotypes with no evident invasions at the tumour margins. Luciferase signals were detected in the contralateral unlabelled recipient tumours for both the U87MG and MU20 tumours compared to the non-implanted control brain. Remarkably, tumour cells were uniformly detected in all tissue samples of the supratentorial brain region compared to the control tissue, with single tumour cells detected in some tissue samples. Circulating tumour cells were also detected in the blood samples of most of the xenografted mice. Moreover, tumour cells were detected in the lungs of all of the mice, a probable event related to haematogenous dissemination. Similar results were obtained when the U87MG cells were alternatively labelled with gaussian luciferase.

CONCLUSIONS

These findings describe a systemic disease model for glioblastoma which can be used to investigate recurrence biology and therapeutic efficacy towards recurrence.

Effect of breast-conserving surgery plus radiotherapy versus mastectomy on breast cancer-specific survival for early-stage contralateral breast cancer

Background

Breast-conserving surgery followed by radiotherapy is recommended in most women with early-stage unilateral breast cancer. However, its role in contralateral breast cancer (CBC) patients remains unclear. This retrospective study aimed to evaluate the breast cancer-specific survival (BCSS) outcomes after breast-conserving surgery plus radiotherapy compared with mastectomy in women with early-stage (T1-2N0-1M0) CBC.

Methods

Data were extracted from the Surveillance, Epidemiology, and End Results database. BCSS was analyzed using the log-rank method, competing risks regression model, and propensity score matching method.

Results

A total of 9,336 early-stage CBC patients were included. After multivariable adjustment, no significant difference in BCSS was found between early-stage CBC patients undergoing breast-conserving surgery plus radiotherapy and those undergoing mastectomy [hazard ratio (HR) 1.11, 95% confidence interval (CI): 0.90-1.37, P=0.329]. BCSS was similar in both treatment groups and in the subgroups stratified by age at first primary breast cancer or CBC diagnosis (≤50, 51-60, and >60 years), time interval between cancers (<0.25, 0.25-4, 5-9, and ≤10 years), stage of first primary breast cancer, T classification of CBC, histology and hormone receptors status of both cancers (all P>0.05). Among patients with N1 disease at CBC diagnosis, breast-conserving surgery plus radiotherapy was associated with a boundary significantly improved BCSS (HR 1.45, 95% CI: 1.00-2.12, P=0.050). Among patients who underwent breast-conserving surgery for first primary cancer, bilateral mastectomy for contralateral cancer did not improve BCSS compared with breast-conserving surgery plus radiotherapy (P>0.05). There was no significant difference in BCSS between breast-conserving surgery plus radiotherapy and mastectomy plus radiotherapy (P>0.05). Stable results were obtained after propensity score matching.

Conclusions

Breast-conserving surgery plus radiotherapy did not significantly influence BCSS outcomes of patients with early-stage CBC. Bilateral mastectomy and mastectomy plus radiotherapy did not confer a survival advantage over breast-conserving surgery plus radiotherapy in these patients. Future prospective studies are necessary to expand on these results.

Contralateral risk-reducing local therapy in breast cancer patients with BRCA1/2 mutations: systemic review and meta-analysis

BACKGROUND

Unilateral breast cancer (UBC) patients with germline pathogenic BRCA1/2 variants have a higher risk of developing contralateral breast cancer (CBC) and need contralateral risk-reducing local treatments, including contralateral risk-reducing mastectomy (CRRM) and prophylactic irradiation (CPI). The aim of our study was to systematically explore the efficacy of CRRM and CPI in reducing CBC risk and increasing survival.

METHODS

A search was done, and eligible randomized trials and cohort studies should include and compare UBC patients with germline pathogenic BRCA1/2 variants who have and have not received contralateral risk-reducing local treatment. Random-effects meta-analysis was used in this study. Primary outcomes of the studies included overall survival (OS) and the incidence of contralateral breast cancer (CBC), and secondary outcomes included breast cancer-specific survival (BCSS).

RESULTS

A total of five studies with 1769 UBC patients with germline pathogenic BRCA1/2 variants were enrolled in our meta-analysis. CRRM was correlated with a lower risk of CBC in UBC patients with germline pathogenic BRCA1/2 variants (summary RR = 0.07; 95%CI 0.03-0.13, I2 = 3%), a significantly increased OS (summary RR, 1.15; 95%CI 1.04-1.26, I2 = 26%) and a significantly increased BCSS (summary RR, 1.18; 95%CI 1.07-1.31, I2 = 64%) compared with surveillance. CPI also decreased the risk of CBC (RR 0.02; 95%CI 0.05-0.88) but did not significantly improve OS (RR 0.97; 95%CI 0.90-1.05) and BCSS (RR 0.97; 95%CI 0.90-1.05) compared with surveillance.

CONCLUSIONS

CRRM reduces CBC risk and increases OS and BCSS in UBC patients with germline pathogenic BRCA1/2 variants, and could be offered as a risk-reducing local treatment. For those who oppose CRRM, CPI could be offered for CBC-risk reduction, while its survival benefit is still uncertain.

Prophylactic irradiation to the contralateral breast for BRCA mutation carriers with early-stage breast cancer

BACKGROUND

Women who carry germ-line mutations in BRCA1/2 are at very high risk of developing breast and ovarian cancer. Breast conserving therapy is associated with a similar risk of ipsilateral cancer recurrence in BRCA carriers compared with non-carriers. However, the risk of subsequent contralateral breast cancer in carriers is markedly increased. Therefore, mastectomy of the diseased breast along with risk reducing mastectomy of the contralateral breast is often advocated for BRCA carriers who are treated for early breast cancer. Yet, many BRCA carriers forgo this option for fear of harmful effects and choose breast conserving treatment and observation instead. In Israel, BRCA-associated breast cancer is relatively common. Accordingly, a national protocol was devised for this enriched population.

PATIENTS AND METHODS

In this Institutional Review Board-approved phase II trial, the option of prophylactic irradiation to the contralateral breast, in addition to standard loco-regional treatment, was offered to BRCA carrier patients treated for early breast cancer who declined contralateral mastectomy. The primary end point was contralateral breast cancer.

RESULTS

Between May 2007 and October 2017, 162 patients were enrolled. Eighty-one patients opted for standard loco-regional treatment including surgery and radiation to the involved side (control arm) and 81 patients chose additional contralateral breast irradiation (intervention arm). At a median follow-up of 58 months, 10 patients developed contralateral breast cancer in the control arm at a median of 32 months, as compared with 2 patients in the intervention arm who developed contralateral breast cancer 80 and 105 months after bilateral breast irradiation (log-rank P = 0.011).

CONCLUSIONS

Among BRCA carrier patients treated for early breast cancer, the addition of contralateral breast irradiation was associated with a significant reduction of subsequent contralateral breast cancers and a delay in their onset.

CLINICAL TRIAL

Phase II, comparative two-arm trial (NCT00496288).

Prophylactic breast irradiation reduces background parenchymal enhancement (BPE) on MRI: A secondary analysis

PURPOSE

We recently showed that prophylactic breast irradiation (PBI) reduces the risk of contralateral breast cancer in BRCA mutation carriers undergoing treatment for early breast cancer. It has been suggested that Background Parenchymal Enhancement (BPE) may be a biomarker for increased risk of breast cancer.

METHODS

For participants in the trial we reviewed the MRI prior to enrollment and following radiation treatment and scored the contralateral breast for BPE and density.

RESULTS

Significant reduction of BPE was more commonly noted following PBI (p = 0.011) compared to the control group.

CONCLUSION

Reduction of BPE by PBI may contribute to its prophylactic effect.

Recombinant human endostatin enhances the radioresponse in esophageal squamous cell carcinoma by normalizing tumor vasculature and reducing hypoxia

The aim of this study was to investigate the effect of recombinant human endostatin (rh-Endo) in combination with radiation therapy (RT) on esophageal squamous cell carcinoma (ESCC) and explore the potential mechanisms. ECA109-bearing nude mice were administered RT and/or rh-Endo treatment. Tumor volume, survival, hypoxia and vascular parameters were recorded during the treatment schedule and follow-up as measures of treatment response. ESCC cell lines (ECA109 and TE13) and human umbilical vein endothelial cells (HUVECs) were developed to investigate the outcomes and toxicities of rh-Endo and RT in vitro. Hypoxia inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) were also evaluated. In vivo studies of ECA109-bearing xenografts showed that rh-Endo improved the radioresponse, with normalization of tumor vasculature and a reduction in hypoxia. In vitro studies showed that rh-Endo did not radiosensitize ESCC cell lines but did affect endothelial cells with a time- and dose-dependent manner. Studies of the molecular mechanism indicated that the improved radioresponse might be due to crosstalk between cancer cells and endothelial cells involving HIF and VEGF expression. Our data suggest that rh-Endo may be a potential anti-angiogenic agent in ESCC especially when combined with RT. The improved radioresponse arises from normalization of tumor vasculature and a reduction in hypoxia.

Effects of Radiation Therapy on Breast Epithelial Cells in BRCA1/2 Mutation Carriers

Women carrying BRCA1 and BRCA2 mutations have significantly elevated risk of developing breast and ovarian cancers. BRCA1-associated breast cancer likely originates from progenitors of the luminal epithelial lineage. Recent studies indicate that radiation therapy (RT) for BRCA1 cancer patients is associated with lower incidence of developing subsequent ipsilateral breast cancer. In the current study, we analyzed tumor-free breast tissue procured via prophylactic bilateral mastectomy from three BRCA1 and one BRCA2 mutation carriers, who had been previously treated with RT for unilateral breast cancers. Freshly isolated breast cells from the irradiated and nonirradiated breast tissue of the same individuals were subjected to flow cytometry, using established cell-surface markers. Two out of the three BRCA1 carriers and one BRCA2 carrier exhibited significantly diminished luminal cell population in the irradiated breast versus the nonirradiated side. There was also RT-associated reduction in the colony-forming ability of the breast epithelial cells. Our finding suggests that prior RT could result in the depletion of the luminal epithelial compartment and thus reduced incidence of BRCA1/2-associated breast cancer.

Advances in the use of radiotherapy to reduce second breast cancers

David Brenner* speaks to Ruth Williamson, Commissioning Editor of Breast Cancer Management: David Brenner focuses on developing mechanistic models for the effects of ionizing radiation on living systems, dividing his research between the effects of high doses of ionizing radiation (relating to radiation therapy) and the effects of low doses of radiation (relating to medical, environmental and occupational exposures). In the field of medical imaging, he has focused on the risk–benefit balance of higher-dose imaging techniques; and in the field of radiotherapy, he has focused on optimizing fractionation schemes for different tumor types, to maximize tumor killing and minimize serious side effects. As well as being Director of the Center for Radiological Research (Columbia University, CO, USA), Brenner is the Director of the Radiological Research Accelerator Facility (Columbia University) and principal investigator of the Center for High-Throughput Minimally-Invasive Radiation Biodosimetry (Columbia University).