Number of lymph nodes examined and prognosis among pathologically lymph node-negative patients after preoperative chemoradiation therapy for rectal adenocarcinoma

Abstract

BACKGROUND Preoperative chemoradiation for rectal cancer can decrease the number of evaluable lymph nodes. Hence, the prognostic role of lymph node evaluation in patients with rectal cancer who receive preoperative chemoradiation is unclear. The authors of this report evaluated the prognostic impact of the number of lymph nodes examined in patients with rectal cancer who had negative lymph nodes based on the pathologic extent of disease (ypN0) after they received preoperative chemoradiation. METHODS Between 1990 and 2004, 372 patients with nonmetastatic rectal adenocarcinoma received preoperative chemoradiation followed by mesorectal excision and had ypN0 disease. The median radiation dose was 45 gray, and 68% of patients received adjuvant chemotherapy. RESULTS Patients had a median of 7 lymph nodes examined after preoperative chemoradiation. Compared with patients who had ≤7 lymph nodes examined, patients who had >7 lymph nodes had higher 5-year rates of freedom from relapse (86% vs 72%; log-rank P = .005) and cancer-specific survival (95% vs 86%; log-rank P = .0004), but no significant difference was observed in the overall survival rate (87% vs 81%; log-rank P = .07). Multivariate Cox proportional models demonstrated that patients who had >7 lymph nodes examined had a significantly lower risk of relapse (hazard ratio [HR], 0.39; P = .003) and death from rectal cancer (HR, 0.45; P = .04) but a similar risk of all-cause mortality (HR, 0.75; 95% CI, 0.46–1.20; P = .23) compared with patients who had ≤7 lymph nodes examined. CONCLUSIONS The number of lymph nodes examined was associated independently with disease relapse and cancer-specific survival in patients with rectal cancer who had ypN0 disease after receiving preoperative chemoradiation. Hence, the authors concluded that the number of negative lymph nodes examined may be a prognostic factor in patients with rectal cancer who receive preoperative chemoradiation.

In rectal cancer, the type of desmoplastic response after preoperative chemoradiotherapy is associated with prognosis

“…Several other factors, such as high ypT stage [22], small number of lymph nodes examined [23], lymphovascular invasion [24], positive circumferential resection margin [7,25], and higher level of carcinoembryonic antigen [26], also appear to have an adverse prognostic impact in this setting. However, our results suggest that the adverse impact on HR hazard ratio, CI confidence interval, CRM circumferential resection margin, LN lymph node, DR desmoplastic reaction, PR peritoneal reflection, NS not selected postoperative survival of immature DR might be more important than these conventional factors, although this needs to be validated in independent cohorts.…”

Neoadjuvant therapy does not affect lymph node ratio in rectal cancer

“…Some researchers question the need for definitive surgery after a 'potentially-curative' neoadjuvant therapy. 9,10 However, other studies demonstrate that a substantial number of patients will retain evidence of positive nodal involvement after neoadjuvant therapy, which has an adverse prognostic impact. 10,11 This has led to some investigations into the genetic basis of resistance to neoadjuvant therapy.…”

“…9,10 However, other studies demonstrate that a substantial number of patients will retain evidence of positive nodal involvement after neoadjuvant therapy, which has an adverse prognostic impact. 10,11 This has led to some investigations into the genetic basis of resistance to neoadjuvant therapy. 12 Our study and its findings potentially adds to the ability to predict prognosis in these patients who are resistant to neoadjuvant therapy.…”

Low Lymph Node Retrieval After Preoperative Chemoradiation for Rectal Cancer is Associated with Improved Prognosis in Patients with a Good Tumor Response

“…17 In addition, Tsai et al conducted a study on 372 patients with lymph node-negative rectal cancer who received preoperative chemoradiation; patients who had[7 lymph nodes retrieved had a significantly lower rate of recurrence and cancer-specific survival. 18 However, those studies had no standardized assessment for all patients over the 10-year period, which may have resulted in inaccurate staging that could affect prognosis. Recent retrospective studies with standardized surgical and pathologic techniques have failed to show any correlation between the number of lymph nodes retrieved and patient outcome after rectal cancer surgery after preoperative chemoradiation.…”