Background: We investigated patterns of failure in patients with locally advanced rectal cancer (LARC) according to chemoradiotherapy (CRT) timing: pre-operative versus post-operative. Also, patterns of failure, particularly distant metastasis (DM), were analyzed according to tumor location within the rectum.
Methods: In total, 872 patients with LARC who had undergone concurrent CRT and radical surgery between 2001 and 2007 were analyzed retrospectively. Concurrent CRT was administered pre-operatively (cT3-4) or post-operatively (pT3-4 or pN+) in 550 (63.1%) and 322 (36.9%) patients, respectively. Median follow-up period was 86 (range, 12-133) months for 673 living patients. Local recurrence (LR) was defined as any disease recurrence within the pelvis, and any failure outside the pelvis was classified as a DM. Only the first site of recurrence was scored.
Results: In total, 226 (25.9%) patients developed disease recurrence. In the pre-operative CRT group, the incidences of isolated LR, combined LR and DM, and isolated DM were 17, 21, and 89 patients, respectively. In the post-operative CRT group, these incidences were 8, 15, and 76 patients, respectively. LR within 2 years constituted 44.7% and 60.9% of all LRs in the pre-operative and post-operative CRT groups, respectively. Late (> 5 years) LR comprised 13.2% and 4.3% of all LRs in the pre-operative and post-operative CRT groups, respectively. The lung was the most common DM site (108/249, 43.4%). Lung or para-aortic lymph node metastasis developed more commonly from low-to-mid rectal tumors while liver metastasis developed more commonly from upper rectal tumors. Lung metastasis occurred later than liver metastasis (n = 54; 22.6 ± 15.6 vs. 17.4 ± 12.1 months; P = 0.035).
Conclusions: This study showed that LARC patients receiving pre-operative CRT tended to develop late LR more often than those receiving post-operative CRT. Further extended follow-up than is conventional may be necessary in LARC patients who are managed with optimized multimodal treatments, and the follow-up strategy may need to be individualized according to tumor location within the rectum.