M. Simpson1, J. Blank1, A. Szabo2, D. Eastwood2, K. Hu1, K. Ludwig1, C. Peterson1, T. Ridolfi1 1Medical College Of Wisconsin,Department Of Surgery,Milwaukee, WI, USA 2Medical College Of Wisconsin,Milwaukee, WI, USA
Introduction: Standard treatment for locally advanced rectal adenocarcinomas (stage II-III) includes neoadjuvant chemoradiation followed by surgical resection and adjuvant chemotherapy. Following this standard treatment scheme 10%-30% achieve a complete response (CR) with no primary tumor remaining on either clinical or pathologic exam. To improve CR rates novel treatment approaches of systemic chemotherapy in addition to neoadjuvant chemoradiation have been suggested. In recent studies, these approaches have been shown to improve CR rates, tumor downstaging, and patient compliance. This study aims to quantify the incidence of neoadjuvant chemotherapy use at our institution, determine patient and tumor characteristics associated with the use of neoadjuvant chemotherapy, and evaluate tumor response to neoadjuvant chemotherapy compared to standard treatment.
Methods: A retrospective chart review was conducted on patients with locally advanced rectal cancer treated at the Medical College of Wisconsin between January 1, 2008 and June 6, 2018. Patient demographics, tumor characteristics, staging information, and treatment modalities were abstracted from the electronic medical record. CR was recorded and included both pathologic CR (pCR), defined as no residual tumor in resected samples, and clinical CR (cCR), defined as no evident disease detected on imaging or examination. The association between neoadjuvant chemotherapy and other variables was assessed with chi-square tests for categorical variables and F tests for continuous variables. Statistical significance was defined as a p-value < 0.05.
Results: A total of 835 patients with rectal cancer were identified, of which 178 met inclusion criteria. 134 patients (75%) underwent standard therapy while 44 (25%) underwent neoadjuvant chemotherapy. 93% of patients receiving neoadjuvant chemotherapy had node-positive disease and 30% had T4 disease, compared to 70% with node-positive disease and 9% with T4 disease in the standard therapy group. In the first half of the study period (2008-2012), 3 of 87 patients received neoadjuvant chemotherapy (3%) while in the second half of the study (2013-2018) 41 of 91 patients received neoadjuvant chemotherapy (45%). Among those receiving standard treatments, 26/134 (19%) achieved a CR, while 16/44 (36%) who received neoadjuvant chemotherapy achieved a CR.
Conclusion: The use of neoadjuvant chemotherapy for locally advanced rectal adenocarcinomas was increasingly utilized at our institution from 2008 to 2018. Patients chosen for neoadjuvant chemotherapy typically had more advanced disease yet achieved CR at a higher rate compared to those undergoing standard therapy. These data confirm trends seen at other institutions and provide rationale for further study into the use of neoadjuvant chemotherapy in the treatment of rectal cancer.