N. Ghalyaie1, K. S. Goodman2, C. S. Lau2,3, R. S. Chamberlain2,3,4 1Banner MD Anderson Cancer Center,Surgery,Gilbert, AZ, USA 2Saint Barnabas Medical Center,Surgery,Livingston, NJ, USA 3Saint George’s University,Grenada, Grenada, Grenada 4Rutgers University,Surgery,Newark, NJ, USA
Introduction: Surgery and either neodadjuvant or adjuvant therapy is the gold standard treatment for rectal cancer. Advances in fluoropyridine-based neoadjuvant chemoradiation (NCR) regimens have resulted in a high percentage of rectal cancer patients exhibiting a complete pathologic response (pCR) after proctectomy. This implies that a subset of patients may be able to undergo surveillance and ultimately not require proctectomy. This study sought to examine the impact of the time between completion of NCR and definitive surgical therapy on the likelihood of a achieving a pCR.
Methods: A comprehensive literature search of PubMed, Google Scholar, Medline, and the Cochrane Central Registry of Controlled Trials (1966-2016) was conducted. Keywords searched included rectal cancer, neoadjuvant chemoradiation, and surgery, and only articles written in English were included. The outcome analyzed was the incidence of pCR.
Results: 13 studies involving 2,731 patients with stage I, II, or III rectal cancers were included. Studies ranged from neoadjuvant chemoradiation completed 41 days prior to surgery to 12 weeks prior to surgery. 13 of the studies reported higher pCR rates following extended intervals (>6-8 weeks) between neoadjuvant chemoradiation and surgery, 5 of which were statistically significantly. Results ranged from 27.1% – 34.5% for extended intervals, compared to 15.3% – 27.3% for shorter intervals (<6-8 weeks) between neoadjuvant chemoradiation and surgery.
Conclusions: Neoadjuvant chemoradiation is capable of achieving a pCR in 15 – 34.5% of patients with rectal cancer. The optimal interval between NCR and surgery is controversial, however, prolonging the interval time between neoadjuvant cheomradiation and surgery (>6-8 weeks) may increase the chance of pCR, especially with Stage II and III rectal cancer. Additional studies evaluating which specific patients (eg.,T2 N0-2, or T3 N0-2) are most likely to achieve pCR, and the impact of a prolongation in the interval between NCR and definitive surgical therapy is needed.