Gastrointestinal tract, Other, Radiation therapy / Oncology, Blood, Radiotherapy techniques
M. Or, A. Koti, B. Arunasalan, J. Lam, E. Hau, H. Gee, P. Sundaresan; Westmead, NSW/AU
- A systematic search of electronic databases (MEDLINE, PubMed and EMBASE) was performed for relevant studies published until November 2019.
- Studies were screened as per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flowchart.
- The relevant studies were selected for full-text review.
Inclusion / Exclusion Criteria
- Studies that met the following criteria were included: human published studies with patients diagnosed with locoregional advanced rectal adenocarcinoma (T3/T4 tumours and/or nodal disease); patients whom received neoadjuvant long-course chemoradiation followed by surgery with concurrent chemotherapy; studies that report potential blood-based biomarker(s) obtained before neoadjuvant chemoradiation; and studies that report potential biomarker predictive for any pathological response (including pathological complete response).
- Colorectal cancer is one of the leading causes of mortality in developed countries. Rectal cancers accounts for a third.
- The current standard of care for patients with locally advanced rectal cancer (T3/T4 tumours and/or nodal disease) is neoadjuvant therapy (short-course radiation therapy or long-course concurrent chemoradiation) followed by radical surgery and adjuvant chemotherapy.
- Following neoadjuvant chemoradiation (nCRT), 15 to 27% of patients have a pathological complete response (pCR)1,2 at surgery, defined as no residual viable tumour at pathological examination.
- There has been increasing interest in predictive biomarker for response to nCRT. The prediction of response is of importance as those who have clinical complete response after nCRT could be managed by “watchful waiting” and avoid the potential morbidity of surgery such as a permanent colostomy3.
- The variation in nCRT response may be contributed by the differential interaction between the patient’s tumour microenvironment and the immune system4,5.
- Recently, blood-based biomarkers are increasingly recognized as a practical screening tool, as they are minimally invasive, easily accessible, and can be measured accurately using standardized methods.