Abstract: Objective:To investigate the risk factors of pulmonary metastasis and prognosis of patients with rectal cancer after anterior resection of rectal cancer.
Methods:The retrospective casecontrol study was adopted. The clinical data of 421 patients with rectal cancer who underwent anterior resection at the First Hospital of China Medical University from August 2010 to December 2014 were collected. The patients were followed up by outpatient examination and telephone interview once three months in the first postoperative year, once half a year in the second postoperative year, and then once a year. The followup included satuses of pulmonary metastasis and survival of patients after anterior resection of rectal cancer. The end point of followup was death of the patients or 31 December, 2014. The risk factors of pulmonary metastasis and prognosis in patients after anterior resection of rectal cancer were analyzed. Measurement data with normal distribution were presented as ±s and measurement data with skewed distribution were presented as M(range).The pulmonary metastasis rate/curve and survival rate/curve were calculated and drawn by the KaplanMeier method. The comparisons of pulmonary metastasis rate and survival rate were done using the Logrank test.The univariate analysis was done using the chisquare test and Logrank test. The multivariate analysis was done by Logistic regression model and COX regression model.
Results Of the 421 patients, 389 patients were successfully followed up with a median time of 34 months (range,11-53 months) and a followup rate of 92.40%(389/421). Ninetyfour, 168 and 127 patients were detected in Ⅰ, Ⅱ and Ⅲ stages of TNM stage. There were 29 patients diagnosed with postoperative pulmonary metastasis with the diagnosis time of (21± 9) months. The 3year cumulative incidence of pulmonary metastasis after anterior resection of rectal cancer was 2.2% in patients of Ⅰ stage, 3.0% in patients of Ⅱ stage and 17.4% in patients of Ⅲ stage, showing significantly increase trend as the increase of the TNM stage (χ²=19.927,P<0.05). The 29 patients with pulmonary metastasis did not receive chemoradiotherapy including 6 patients receiving pulmonary metastatic nodule recection. Nineteen patients were survived and 10 patients were dead. The survival time of patients diagnosed with pulmonary metastasis was (13±9)months and the 3year cumulative survival rate was 75.7%, whereas the survival time of patients without postoperative pulmonary metastasis was (35±9)months and the 3year cumulative survival rate was 94.3%, showing significant difference between the 2 kinds of patients (χ²=25.219, P<0.05). The univariate analysis showed that the preoperative carcinoembryonic antigen (CEA) level, degree of tumor differentiation, depth of invasion and lymph node metastasis were risk factors affecting pulmonary metastasis after anterior resection of rectal cancer (χ²=4.745, 7.250, 5.379, 18.796, P<0.05), and the multivariate analysis showed that lymph node metastasis was an independent risk factor affecting postoperative pulmonary metastasis ［OR=4.167, 95% confidence interval (CI): 1.608-10.801, P<0.05］. The univariate analysis showed that the preoperative CEA level, distribution and number of pulmonary metastatic nodule and lymph node metastasis were risk factors affecting the prognosis of patients with pulmonary metastasis after anterior resection of rectal cancer (χ²=13.793, 7.246, 6.284, 4.076, P<0.05), and the multivariate analysis showed that the preoperative CEA level >5 μg/L was an independent risk factor affecting the prognosis of patients (HR=13.489, 95% CI: 1.407-129.297, P<0.05).
Conclusions: Pulmonary metastasis after anterior resection of rectal cancer is common. Lymph node metastasis is a high risk factor affecting postoperative pulmonary metastasis, and preoperative CEA level>5 μg/L is an independent risk factor affecting the prognosis of patients with postoperative pulmonary metastasis.