Impact of interval between neoadjuvant chemoradiotherapy and TME for locally advanced rectal cancer on pathologic response and oncologic outcome.

BACKGROUND: The interval between neoadjuvant chemoradiotherapy and surgery for rectal cancer has arbitrarily been set at 6-8 weeks. However, tumor regression is variable. This study aimed to evaluate whether the interval between neoadjuvant therapy and surgery had an impact on pathologic response and on surgical and oncologic outcome. METHODS: A total of 356 consecutive patients with clinical stage II and III rectal adenocarcinoma were identified. Median age was 63 years, and 65 % were men. All patients received neoadjuvant chemoradiotherapy (45 Gy) with a continuous infusion of 5-fluorouracil. Data on neoadjuvant-surgery interval, type of surgery, pathology, postoperative complications, length of hospital stay, disease recurrence, and survival were reviewed. Patients were divided into two groups according to the interval between neoadjuvant therapy and surgery: ≤ 7 weeks (short interval, n = 201) and >7 weeks (long interval, n = 155). RESULTS: The complete pathologic response rate was 21 %. It was significantly higher after a longer interval (28 %) than after a shorter interval (16 %, p = 0.006). A longer interval did not affect morbidity or length of hospital stay. After a median follow-up of 4.9 years, the 5-year cancer-specific survival rate was 83 % in the short-interval group versus 91 % in the long-interval group (p = 0.046), and the free-from-recurrence rate was 73 versus 83 %, respectively (p = 0.026). CONCLUSIONS: In this retrospective analysis, there seems to be an association between a longer interval after neoadjuvant chemoradiotherapy and complete pathologic response without affecting postoperative morbidity and length of hospital stay, and with no detrimental effect on oncologic outcome.