Timing of surgery after long-course neoadjuvant chemoradiotherapy for rectal cancer: a systematic review of the literature.

BACKGROUND:
Neoadjuvant long-course chemoradiotherapy is commonly used to improve the local control and resectability of locally advanced rectal cancer, with surgery performed after an interval of a number of weeks.

OBJECTIVE:
We report an evidence-based systematic review of published data supporting the optimal time to perform surgical resection after long-course neoadjuvant therapy.

DATA SOURCES:
A systematic literature search was undertaken of the MEDLINE and Embase electronic databases from 1995 to 2012.

STUDY SELECTION:
English language articles were included that compared outcomes following rectal cancer surgery performed at different times after a long course of neoadjuvant radiation-based therapy.

INTERVENTIONS:
Patients received a long course of neoadjuvant therapy followed by radical surgical resection after an interval period.

MAIN OUTCOME MEASURES:
The rates of tumor response, R0 resection, sphincter preservation, surgical complications, and disease recurrence were the primary outcomes measured.

RESULTS:
Fifteen studies were identified: 1 randomized controlled trial, 1 prospective nonrandomized interventional study, and 13 observational studies. Studies compared time intervals that varied between 12 weeks, with a large degree of variation in what the standard interval length was considered to be. Four of the 7 studies that reported rates of pathological complete response identified significantly higher rates with an extended interval between chemoradiotherapy and surgery; 3 of 8 studies demonstrated increased primary tumor downstaging with a longer interval. No significant differences have been consistently demonstrated in rates of surgical complications, sphincter preservation, or long-term recurrence and survival.

LIMITATIONS:
Neoadjuvant regimes, indications for neoadjuvant therapy, and time intervals after chemoradiotherapy were heterogeneous between studies; consequently, meta-analysis could not be performed.

CONCLUSIONS:
There is limited evidence to support decisions regarding when to resect rectal cancer following chemoradiotherapy. There may be benefits in prolonging the interval between chemoradiotherapy and surgery beyond the 6 to 8 weeks that is commonly practiced. However, outcomes need to be studied further in robust randomized studies.