C. Nganzeu1, J. J. Blank1, F. Ali1, W. Hall2, C. Peterson1, K. Ludwig1, T. Ridolfi1 2Medical College Of Wisconsin,Department Of Radiology,Milwaukee, WI, USA 1Medical College Of Wisconsin,Department Of Colorectal Surgery,Milwaukee, WI, USA
Introduction:
The standard treatment of stage II or III rectal adenocarcinoma is chemoradiation therapy (CRT) followed by surgical resection and adjuvant systemic chemotherapy. Recently there has been increased interest in the use of induction chemotherapy (IC), an approach that provides some or all systemic chemotherapy and CRT in the preoperative setting. Potential benefits of this treatment paradigm include tumor downstaging, early treatment of micrometastases, increased rate of sphincter preservation, decreased time with a diverting stoma, and patient compliance. However, little is known about this treatment strategy on a national level. The aims of this study were to define the frequency of IC use and evaluate treatment outcomes compared to standard CRT using the National Cancer Database.
Methods:
The National Cancer Database was queried for patients diagnosed with stage II or III rectal adenocarcinoma having received radiation, chemotherapy and surgical resection between 2004 and 2014. We compared patients with IC to patients having received standard combined CRT. Linear regression was performed to predict percent patients receiving IC by year. Propensity score matching was applied in a 1:10 fashion. A logistic model was fitted to obtain propensity scores. A greedy matching algorithm was then applied for predictor selection. Outcomes including downstaging, readmission, positive margins, and survival were evaluated.
Results:
A total of 33,480 patients met inclusion criteria. 96.4% of patients underwent standard CRT while 3.6% underwent IC. Of all patients diagnosed with stage II and III rectal cancer, only 2.8% received IC in 2004; this number rose to 4.4% in 2014. Propensity score matching yielded 10,531 patients receiving standard CRT and 1,073 patients who received IC for the analysis. The IC group had more tumor downstaging than standard CRT on surgical pathology (54% vs. 48.8%, p=0.006, respectively). This group also had significantly fewer 30-day readmissions after surgery (4.5% vs. 6.4%, p=0.021, respectively). There were no differences observed in 30-day or 90-day mortality (0.5% vs. 0.5%, p= 0.247 and 0.8% vs. 1.1%, P= 0.755, respectively), rate of positive margins (4.8% vs. 5.6%, p=0.398, respectively), or survival (p=0.587) between the two groups.
Conclusion:
The use of induction chemotherapy for patients with stage II and III rectal cancer increased significantly from 2004-2014. Induction chemotherapy was associated with improved downstaging before surgery and improved 30-day readmission rates after surgery without changing overall survival when compared to standard chemoradiation therapy.
