About this Research Topic
Circulating tumor DNA (ctDNA) testing is rapidly emerging as a new tool for scientists and oncologists treating gastrointestinal cancers. The varied numbers of testing platforms, either research or the ones that are commercially available, are helping us understand several fundamental aspects of tumor biology. For example, tumor heterogeneity and tumor evolution is a concept that we as oncologists have always known about and seen in patients being treated for any of the gastrointestinal cancers. However, it is now through ctDNA testing that we are truly gaining an understanding of how things are evolving and what are the mechanisms underlying this change.
Its ease of use, non-invasiveness, dynamic nature of assessment and increasing sensitivity and specificity in terms of assessing the depth and breadth of the varying ctDNA aberrations, it has the potential of transforming care of patients with gastrointestinal cancers. In fact one can argue that it probably already is. It will not be too long before societies and guidelines endorse its use as we gain a better understanding of the impact it can have.
In the upcoming years, we foresee its routine use in the clinic to include:
(i) Detection of early recurrences
(ii) Identification of individuals as candidates for chemotherapy versus no chemotherapy in the adjuvant setting
(iii) Identification of individuals candidates for aggressive curative-intent approaches e.g. metastasectomies for patient with oligometastatic cancers
(iv) Identification of mechanisms of resistance for patients on chemotherapy and/or targeted therapies/biologics
(v) Early identification of treatment failures well before the next set of imaging
(vi) Identification of new targets that the patients may be eligible for
(vii) Predicting candidates for potentially immunotherapy and/or other targeted therapies
(viii) As a reliable biomarker; beyond just estimating prognosis
(ix) Identifying candidates who may not need surgery after neoadjuvant therapy e.g. patients with esophageal and rectal cancers receiving neoadjuvant chemoradiation
(x) Increasing the number of patients eligible for potential therapies by capturing the full spectrum of intra- and inter-tumor heterogeneity as well as capturing it early
(xi) Increase accrual as well as benefit that patients derive from clinical trials by identifying the right treatment for the right patient.
The aim of our Research Topic is provide a platform for articles of all types addressing the potential impact and challenges of ctDNA testing in patients with gastrointestinal cancers. As this field continues to evolve, it would be important to address the fundamental questions on why, when, how, and which patients with gastrointestinal cancers would be ideally suited to ctDNA testing.
Keywords: Gastrointestinal malignancies, circulating tumor DNA (ctDNA), colorectal cancer, liquid biopsy
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