A curative intent trimodality approach for advanced isolated abdominal nodal metastasis in metastatic colorectal cancer: Update of a single-institutional experience.

Abstract

3556 Background: To define and update survival rates and relapse patterns in patients (pts) with isolated advanced abdominal nodal metastasis secondary to colorectal cancer (CRC), treated with curative intent using aggressive trimodality therapy. Methods: Fifty-seven pts with isolated advanced abdominal lymph node metastasis (retroperitoneal and mesenteric) secondary to colorectal cancer received trimodality therapy defined as chemotherapy delivered in conjunction with external beam radiotherapy (EBRT) followed by lymphadenectomy and intraoperative radiotherapy (IORT). Infusional 5-FU was the most common radiosensitizer used (66%, 38 pts). The median dose of EBRT was 50 Gy & the median dose of intraoperative radiotherapy was 12.5 Gy. End points included distant metastasis, toxicities, local failure within EBRT field, recurrence within the intraoperative radiotherapy field, and survival. Results: 49% of pts were male, median age 50.5 yrs. All patients had ECOG ≤ 1. 27 pts had primary right sided colon cancer, 16 left sided colon cancer and 14 rectal primaries. Median time from initial CRC diagnosis to development of abdominal lymph node metastatic disease was 24 months (95% CI, 23.5-45.1 months). 84% (48 pts) had paraaortic nodal metastases, 12% (7 pts) had mesenteric nodal metastases, and 3% (2 pts) had both. With a median follow up of 89.4 months, the median overall survival and 5-year estimated survival rate were 53.2 months (95% CI, 46.4-78.8 months) and 42%, respectively. Median progression free survival was 19.3 months (95% CI, 15.6-32.8 months). 21 (37%) pts never developed distant disease. Outcome was not affected by disease sidedness, rectal primary, or mutational profile. Treatment was well tolerated without any grade 3/4 toxicities. Conclusions: The use of trimodality therapy including EBRT with radiosensitizing chemotherapy, lymphadenectomy and IORT produces sustainable long-term survival in selected metastatic CRC pts presenting with isolated retroperitoneal/mesenteric nodal relapse.