Incorporation of Radiotherapy in the Multidisciplinary Treatment of Isolated Retroperitoneal Lymph Node Recurrence from Colorectal Cancer

This article was designed to study the clinical outcomes and prognostic factors following radiotherapy (RT) in the multidisciplinary management of isolated retroperitoneal lymph node (RPLN) recurrence of colorectal cancer. We identified 52 patients treated consecutively with tumor-directed RT for isolated RPLN recurrence. Twenty-five patients received upfront RT (Group 1). Twenty-seven patients received RT after systemic therapy. The deferred RT was administered either to locally controlled tumors (Group 2, n = 17) or to locally progressive tumors in RPLNs (Group 3, n = 10). The median overall survival and progression-free survival were 41 and 13 months, respectively, with a median follow-up time of 34 months. Survival was not significantly different among three groups. Local recurrence (32/52) was predominant and occurred earlier than distant metastasis (31/52). Two-thirds of the local recurrences (21/32) involved outfield recurrence, which was mostly in the cranial direction (15/21) from the upper margin of the RT volume. Repeated RT successfully salvaged a substantial number of patients. A shorter disease-free interval, low-dose radiation, and a tumor location above the renal vein were independent risk factors for local recurrence (all P < 0.05). A large gross tumor volume was an independent risk factor for distant metastasis (P = 0.037). No acute or late RT-related toxicity a parts per thousand yen grade 3 occurred. Our analysis suggests that both upfront RT and deferred RT incorporated into multidisciplinary management are potentially effective treatment strategies. We found that gross tumor volume, tumor location, and disease-free interval are important prognostic factors and should be taken into consideration to decide the timing of RT.