Survival outcomes after omission of surgery for ductal carcinoma in situ: A National Cancer Database (NCDB) analysis

e12574

Background: Clinical trials of active surveillance (AS) for Ductal Carcinoma in Situ (DCIS) are underway. We sought to understand the historical management of biologically favorable DCIS and to determine the long-term outcomes of patients who did not have surgery at time of diagnosis. We hypothesized that women who had biologically favorable DCIS and underwent AS would have excellent long-term outcomes. Methods: The NCDB was queried from 2004 to 2017 for women diagnosed with DCIS. This cohort was further refined to identify those with biologically favorable DCIS defined as grade 1 or 2 and hormone receptor (HR) positive. Women under age 40 were excluded. AS was defined as either no surgery or surgery >12 months from diagnosis. A Cochran-Armitage test was used to assess the trend of surgery omission over year of diagnosis. Multivariable logistic regression was used to assess association between baseline factors and AS. Kaplan-Meier curves were estimated to show overall survival (OS) in this biologically favorable DCIS group that underwent AS, stratified by age (<50, 50-65, >65). Univariate and multivariable Cox proportional hazard models were used to determine the effects of prognostic factors on survival distributions. Results: There were 74,868 women with grade 1 or 2, HR positive DCIS, of whom 2,384 (3.2%) were treated with AS. The proportion of patients with biologically favorable DCIS who underwent AS increased over time, peaking in 2017 with 4.2% of DCIS cases diagnosed that year treated with observation (p<0.001). Only 17% of the patients in the AS group received hormonal therapy. On multivariable analysis, increasing age (OR 1.02, p<0.001), black race (OR 1.7, p<0.001), and being uninsured (OR 2.2, p<0.001) were all associated with increased likelihood of AS. In an unadjusted analysis, receipt of surgery was associated with improved OS in the entire cohort. However, the OS benefit from surgery differed when stratified by age. In women <50 years of age, OS outcomes were similar, with 10-year OS of 97.4% in the immediate surgery cohort vs 99.1% in AS cohort (p=0.43). In contrast, in women >50 years of age, 10-year OS was higher for women undergoing surgery (85.3% vs 70.0% in AS group, p <0.001). This association with OS in this older cohort persisted even after adjusting for age, race and comorbidity as well as facility demographics. Conclusions: The proportion of patients with low or intermediate grade, hormone receptor positive DCIS not treated with surgery has remained small but is increasing over time. AS of biologically favorable DCIS in younger, healthier women is not associated with adverse survival. In older women, the finding of benefit of surgery over AS is very likely confounded by underlying health factors that are not fully captured with co-morbidity scores.

RIG-I-Like Receptor LGP2 Is Required for Tumor Control by Radiotherapy

Dendritic cells (DC) play an essential role in innate immunity and radiation-elicited immune responses. LGP2 is a RIG-I-like receptor involved in cytoplasmic RNA recognition and antiviral responses. Although LGP2 has also been linked to cell survival of both tumor cells and T cells, the role of LGP2 in mediating DC function and antitumor immunity elicited by radiotherapy remains unclear. Here, we report that tumor DCs are linked to the clinical outcome of patients with breast cancer who received radiotherapy, and the presence of DC correlates with gene expression of LGP2 in the tumor microenvironment. In preclinical models, host LGP2 was essential for optimal antitumor control by ionizing radiation (IR). The absence of LGP2 in DC dampened type I IFN production and the priming capacity of DC. In the absence of LGP2, MDA5-mediated activation of type I IFN signaling was abrogated. The MDA5/LGP2 agonist high molecular weight poly I:C improved the antitumor effect of IR. This study reveals a previously undefined role of LGP2 in host immunity and provides a new strategy to improve the efficacy of radiotherapy. SIGNIFICANCE: These findings reveal an essential role of LGP2 in promoting antitumor immunity after radiotherapy and provide a new strategy to enhance radiotherapy.

DNA Methylation Controls Metastasis-Suppressive 14q32-Encoded miRNAs

Expression of 14q32-encoded miRNAs is a favorable prognostic factor in patients with metastatic cancer. In this study, we used genomic inhibition of DNA methylation through disruption of DNA methyltransferases DNMT1 and DNMT3B and pharmacologic inhibition with 5-Aza-2'-deoxycytidine (5-Aza-dC, decitabine) to demonstrate that DNA methylation predominantly regulates expression of metastasis-suppressive miRNAs in the 14q32 cluster. DNA demethylation facilitated CCCTC-binding factor (CTCF) recruitment to the maternally expressed gene 3 differentially methylated region (MEG3-DMR), which acts as a cis-regulatory element for 14q32 miRNA expression. 5-Aza-dC activated demethylation of the MEG3-DMR and expression of 14q32 miRNAs, which suppressed adhesion, invasion, and migration (AIM) properties of metastatic tumor cells. Cancer cells with MEG3-DMR hypomethylation exhibited constitutive expression of 14q32 miRNAs and resistance to 5-Aza-dC-induced suppression of AIM. Expression of methylation-dependent 14q32 miRNAs suppressed metastatic colonization in preclinical models of lung and liver metastasis and correlated with improved clinical outcomes in patients with metastatic cancer. These findings implicate epigenetic modification via DNA methylation in the regulation of metastatic propensity through miRNA networks and identify a previously unrecognized action of decitabine on the activation of metastasis-suppressive miRNAs. SIGNIFICANCE: This study investigates epigenetic regulation of metastasis-suppressive miRNAs and the effect on metastasis.