Staging the Metastatic Spectrum Through Integration of Clinical and Molecular Features

Characterization of an oligometastatic state in patients with metastatic pancreatic adenocarcinoma undergoing systemic chemotherapy

PURPOSE/OBJECTIVES

Most patients with pancreatic adenocarcinoma (PDAC) will present with distant metastatic disease at diagnosis. We sought to identify clinical characteristics associated with prolonged overall survival (OS) in patients presenting with metastatic PDAC.

MATERIALS/METHODS

Patients presenting with metastatic PDAC that received treatment at our institution with FOLFIRINOX or gemcitabine-based chemotherapies between August 1, 2011 and September 1, 2017 were included in the study. Metastatic disease burden was comprehensively characterized radiologically via individual diagnostic imaging segmentation. Landmark analysis was performed at 18 months, and survival curves were estimated using the Kaplan-Meier method and compared between groups via the log-rank test. ECOG and Charlson Comorbidity Index (CCI) were calculated for all patients.

RESULTS

121 patients were included with a median age of 62 years (37-86), 40% were female, 25% had ECOG 0 at presentation. Of the 121 patients included, 33% (n = 41) were alive at 12 months and 25% (n = 31) were alive at 18 months. Landmark analysis demonstrated a significant difference between patients surviving <18 months and ≥18 months regarding the presence of lung only metastases (36% vs. 16%, p = 0.04), number of organs with metastases (≥2 vs. 1, p = 0.04), and disease volume (mean of 19.1 cc vs. 1.4 cc, p = 0.04). At Year 1, predictors for improved OS included ECOG status at diagnosis (ECOG 0 vs. ECOG 1, p = 0.04), metastatic disease volume at diagnosis (≤0.1 cc vs. >60 cc, p = 0.004), metastasis only in the liver (p = 0.04), and normalization of CA 19-9 (p < 0.001). At Year 2, the only predictor of improved OS was normalization of the CA 19-9 (p = 0.03). In those patients that normalized their CA 19-9, median overall survival was 16 months.

CONCLUSIONS

In this exploratory analysis normalization of CA-19-9 or volumetric metastatic disease burden less than 0.2 cc demonstrated a remarkable OS, similar to that of patients with non-metastatic disease. These metrics are useful for counseling patients and identifying cohorts that may be optimal for trials exploring metastatic and/or local tumor-directed interventions.

The Management of Oligometastases in Non-small Cell Lung Cancer - is Stereotactic Ablative Radiotherapy now Standard of Care?

Oligometastatic non-small cell lung cancer encompasses a number of distinct clinical scenarios with a pattern of limited tumour burden on imaging. Delivering local ablative therapy to individual metastatic lesions may assist in disease modification and contribute to improved outcomes. We review the published randomised clinical trials that support the implementation of stereotactic ablative radiotherapy as a standard of care in certain oligometastatic non-small cell lung cancer clinical scenarios, and highlight the current knowledge gaps and areas of ongoing research.

Thorax radiotherapy using 18F-positron emission tomography/computed tomography-guided precision radiotherapy is a prognostic factor for survival in patients with extracranial oligometastatic non-small cell lung cancer:A two-center propensity score-matched analysis

Background

This retrospective study compared positron emission tomography (PET)/computed tomography (CT) and CT in the treatment of extracranial oligometastatic non-small-cell lung cancer (NSCLC) and explored the impact of thorax radiotherapy (TRT) on patient survival.

Methods

We reviewed the medical records of Chinese patients with stage IV extracranial oligometastatic NSCLC who underwent PET/CT or CT at two centers. Propensity score matching (PSM) was used to control differences in patient characteristics between the maintenance chemotherapy alone and TRT plus maintenance chemotherapy groups.

Results

We analyzed 192 eligible patients. The median survival time was better in patients who received PET/CT than in those who only received CT (n = 192, 16 months vs. 6 months, p<0.001). Subgroup analysis showed the median survival time was significantly longer in the TRT plus maintenance group than in the chemotherapy alone group in patients who underwent PET/CT examinations (n = 94, 25 months vs. 11 months, p<0.001). However, there was no statistical difference in survival between both groups in patients who underwent CT examinations (n = 98, 8 months vs. 5 months, p = 0.180). A multifactorial analysis revealed a more favorable prognosis in patients who underwent PET/CT evaluation (HR: 0.343, 95% CI: 0.250-0.471, p <0.001) and TRT (HR: 0.624, 95% CI: 0.464-0.840, p = 0.002), than in those who did not. PSM was consistent with these results.

Conclusions

PET/CT-guided TRT is associated with improved clinical outcomes in patients with stage IV extracranial oligometastatic NSCLC.

Circulating Tumor DNA Biomarkers for Early Detection of Oligometastasis

Oligometastasis represents an intermediate disease stage between localized and widely metastatic cancer. Efficient identification of patients with oligometastasis remains a barrier for accrual on clinical trials of oligometastasis-directed therapy. Here we review the prospect of circulating tumor DNA-based monitoring to promote sensitive, specific, and cost-efficient detection of cancer recurrence during posttreatment surveillance. Thus, an impetus for the development and implementation of clinical-grade circulating tumor DNA assays should be for the positive impact they will have on clinical investigations of oligometastasis-directed therapy.

Definition, Biology, and History of Oligometastatic and Oligoprogressive Disease

Historical theories of metastasis have been informed by the seed and soil hypothesis, the Halsteadian paradigm proposing an orderly spread from local to distant sites, and the presumption that cancer is an inherently systemic process even in the earliest cases. The more contemporary spectrum theory now suggests that the propensity for distant spread exists along a continuum of metastatic virulence. Tumors with limited metastatic potential represent one subset along this spectrum that could potentially be cured with local ablative therapy. Integrating clinical and molecular features to biologically inform the classification of not only oligometastatic or oligoprogressive disease but also the entire metastatic spectrum holds great promise to improve prognostication and inform clinical decision making. To this end, the inclusion of molecular correlative studies and biospecimen collection on prospective protocols is imperative.

Oligometastasis: Past, Present, Future

In this review, we discuss the oligometastatic state, with a focus on its current and future relevance within the field of radiation therapy. We first outline the scope of the problem and the evolving understanding of metastatic disease existing along a spectrum. We then transition to a discussion of the clinical data that led to the formulation of the oligometastatic hypothesis, delving in some detail into the clinical factors associated with improved outcomes in the setting of local therapy-whether surgical or radiotherapeutic. In particular, we highlight the marked limitations of using clinical criteria alone to determine the absence or presence of true extracranial oligometastatic disease. After this, we briefly discuss the radiation therapy literature that has recently demonstrated benefits in cancer-specific outcomes with ablative treatment of oligometastatic disease. We emphasize data in the setting of non-small cell lung cancer and prostate cancer and briefly discuss the importance of our enhanced ability to detect occult metastatic disease with improved imaging technologies. After noting that resulted and ongoing prospective trials of ablative radiation therapy use the most rudimentary of oligometastatic classifiers-number of metastases-as their inclusion criteria, we transition to our core argument: a growing body of preclinical and translational work aims to refine the definition of oligometastatic disease using molecular features. We address genomic, epigenetic, and immunologic features that have, across histology, demonstrated an improved ability to prognosticate when combined with classic clinical correlates of oligometastatic disease. We also discuss studies that suggest particular molecular targets which, when manipulated for therapeutic purposes, have the potential to revert the polymetastatic phenotype to the oligometastatic one. We conclude with what we believe are the repercussions of this work for radiation therapy trials and clinical practice, and the importance of enriching and supporting these inquiries for the future of our field.

Late Brain Oligometastases Diagnosed at Least 36 Months after Cancer Detection are Associated with Favorable Survival Outcome

Objective  The aim of this study was to investigate the impact of a long disease-free interval (at least 36 months from the first diagnosis of cancer) on survival in patients with brain oligometastases (maximum four lesions, no extracranial metastases). Methods This study involves a retrospective analysis in a group of 89 patients treated with different brain-directed approaches. Results We identified seven patients (8%) with an interval from cancer diagnosis to the development of brain metastases of at least 36 months. The median time interval was five months. The one-year survival rates were 80% (interval of at least 36 months) and 43% (shorter interval), respectively (p = 0.049). Correspondingly, a large difference in actuarial median survival was observed (39.9 months [95% confidence interval, 16.8-63.0 months] versus 9.7 months (95% confidence interval, 6.1-13.3 months). However, the two Kaplan-Meier curves were not statistically significantly different, p = 0.13. In addition to treatment-related differences, the two groups also differed with regard to the type of primary tumor (high versus low rates of non-small cell lung cancer) and gender. Conclusion Late dissemination was uncommon. The often applied strategy of effective local treatment for patients with brain-only oligometastases is warranted, especially if the disease-free interval had been at least 36 months. Larger studies are needed to fully understand the impact of confounding factors, such as gender and tumor biology.