Abstract
BackgroundThe aim of the present study was to evaluate MRI response rate and clinical outcome of short-course radiotherapy (SCRT) on rectal cancer as an alternative to chemoradiotherapy in patients where downstaging is indicated.MethodsA retrospective analysis was performed of a patient cohort with rectal carcinoma (cT1-4cN0-2 cM0–1) from a large teaching hospital receiving restaging MRI, deferred surgery or no surgery after SCRT between 2011 and 2017. Patients who received chemotherapy during the interval between SCRT and restaging MRI were excluded.The primary outcome measure was the magnetic resonance tumor regression grade (mrTRG) at restaging MRI after SCRT followed by a long interval. Secondary, pathological tumor stage, complete resection rate and 1-year overall survival were assessed.ResultsA total of 47 patients (M:F = 27:20, median age 80 (range 53–88) years), were included. In 33 patients MRI was performed for response assessment 10 weeks after SCRT. A moderate or good response (mrTRG≤3) was observed in 24 of 33 patients (73%). While most patients (85%; n = 28) showed cT3 or cT4 stage on baseline MRI, a ypT3 or ypT4 stage was found in only 20 patients (61%) after SCRT (p < 0.01). A complete radiologic response (mrTRG 1) was seen in 4 patients (12%). Clinical N+ stage was diagnosed in n = 23 (70%) before SCRT compared to n = 8 (30%) post-treatment (p = 0.03).After SCRT, 39 patients underwent deferred surgery (after a median of 14 weeks after start of SCRT) and a resection with complete margins was achieved in 35 (90%) patients. One-year overall survival after surgery was 82%. Complete pathological response was found in 2 patients (5%).ConclusionsThe use of SCRT followed by a long interval to restaging showed a moderate to good response in 73% and therefore can be considered as an alternative to chemoradiotherapy in elderly comorbid patients.
Highlights
Colorectal cancer is currently the second most common cancer in the Netherlands, with an incidence of approximately 5000 rectal cancer patients per year
In case of a threatened mesorectal fascia and/or multiple positive lymph nodes, patients are usually treated with long course CRT followed by restaging and Total Mesorectal Excision (TME) resection in case of sufficient downstaging or individualized treatment in persistent Locally advanced rectal cancer (LARC) [4]
Included patients met the following criteria: patients diagnosed with rectal cancer who received short-course radiotherapy (SCRT) and underwent deferred surgery, patients who received SCRT and underwent restaging MR imaging (MRI) or patient who underwent SCRT that did not undergo surgery due to be considered unfit for CRT, due to high age in combination with frailty or due to multiple distant metastasis
Summary
Colorectal cancer is currently the second most common cancer in the Netherlands, with an incidence of approximately 5000 rectal cancer patients per year. In the Netherlands, this combined treatment has been the cornerstone in management of resectable rectal cancer in the past decade and leading to excellent results [3]. According to the Dutch Colorectal Cancer Guidelines, patients diagnosed with intermediate risk rectal cancer (T1-T3 with positive lymph node staging (N1) or T3 N0 with > 5 mm extramural invasion and uninvolved MRF) are treated with neoadjuvant SCRT and are planned for immediate surgery. In case of a threatened mesorectal fascia (cT3/4MRF+) and/or multiple positive lymph nodes (cN2), patients are usually treated with long course CRT followed by restaging and TME resection in case of sufficient downstaging or individualized treatment in persistent LARC [4]. The aim of the present study was to evaluate MRI response rate and clinical outcome of short-course radiotherapy (SCRT) on rectal cancer as an alternative to chemoradiotherapy in patients where downstaging is indicated
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